Publications 2019-04-29T14:20:01+00:00
CHEOPS
Bibcode:

2019A&A...622A..33M

Authors:

Maxted, P. F. L.; Gill, S.

Publication:

Astronomy & Astrophysics, Volume 622, id.A33, 7 pp.

Date

2019 January

Abstract:

Context. The power-2 law, Iλ( μ) = 1 - c(1-μα), accurately represents the limb-darkening profile for cool stars. It has been implemented in a few transit models to-date using numerical integration but there is as-yet no implementation of the power-2 law in analytic form that is generally available.
Aims: Our aim is to derive an analytic approximation that can be used to quickly and accurately calculate light curves of transiting exoplanets using the power-2 limb-darkening law.
Methods: An algorithm to implement the power-2 law is derived using a combination of an approximation to the required integral and a Taylor expansion of the power-2 law. The accuracy of stellar and planetary radii derived by fitting transit light curves with this approximation ...

Context. The power-2 law, Iλ( μ) = 1 - c(1-μα), accurately represents the limb-darkening profile for cool stars. It has been implemented in a few transit models to-date using numerical integration but there is as-yet no implementation of the power-2 law in analytic form that is generally available.
Aims: Our aim is to derive an analytic approximation that can be used to quickly and accurately calculate light curves of transiting exoplanets using the power-2 limb-darkening law.
Methods: An algorithm to implement the power-2 law is derived using a combination of an approximation to the required integral and a Taylor expansion of the power-2 law. The accuracy of stellar and planetary radii derived by fitting transit light curves with this approximation is tested using light curves computed by numerical integration of limb-darkening profiles from 3D stellar model atmospheres.
Results: Our algorithm (qpower2) is accurate to about 100 ppm for broad-band optical light curves of systems with a star-planet radius ratio p = 0.1. The implementation requires less than 40 lines of python code so can run extremely fast on graphical processing units (GPUs; ̃1 million models per second for the analysis of 1000 data points). Least-squares fits to simulated light curves show that the star and planet radius are recovered to better than 1% for p < 0.2.
Conclusions: The qpower2 algorithm can be used to efficiently and accurately analyse large numbers of high-precision transit light curves using Monte Carlo methods.

Bibcode:

2019A&A...621A.117A

Authors:

Akinsanmi, B.; Barros, S. C. C.; Santos, N. C.; Correia, A. C. M.; Maxted, P. F. L.; Boué, G.; Laskar, J.

Publication:

Astronomy & Astrophysics, Volume 621, id.A117, 9 pp.

Date

2018 December

Abstract:

Context. Short-period planets are influenced by the extreme tidal forces of their parent stars. These forces deform the planets causing them to attain nonspherical shapes. The nonspherical shapes, modeled here as triaxial ellipsoids, can have an impact on the observed transit light-curves and the parameters derived for these planets.
Aims: We investigate the detectability of tidal deformation in short-period planets from their transit light curves and the instrumental precision needed. We also aim to show how detecting planet deformation allows us to obtain an observational estimate of the second fluid Love number from the light curve, which provides valuable information about the internal structure of the planet.
Methods: We adopted a model to calculate the shape of a planet...

Context. Short-period planets are influenced by the extreme tidal forces of their parent stars. These forces deform the planets causing them to attain nonspherical shapes. The nonspherical shapes, modeled here as triaxial ellipsoids, can have an impact on the observed transit light-curves and the parameters derived for these planets.
Aims: We investigate the detectability of tidal deformation in short-period planets from their transit light curves and the instrumental precision needed. We also aim to show how detecting planet deformation allows us to obtain an observational estimate of the second fluid Love number from the light curve, which provides valuable information about the internal structure of the planet.
Methods: We adopted a model to calculate the shape of a planet due to the external potentials acting on it and used this model to modify the ellc transit tool. We used the modified ellc to generate the transit light curve for a deformed planet. Our model is parameterized by the Love number; therefore, for a given light curve we can derive the value of the Love number that best matches the observations.
Results: We simulated the known cases of WASP-103b and WASP-121b which are expected to be highly deformed. Our analyses show that instrumental precision ≤50 ppm min-1 is required to reliably estimate the Love number and detect tidal deformation. This precision can be achieved for WASP-103b in ̃40 transits using the Hubble Space Telescope and in ̃300 transits using the forthcoming CHEOPS instrument. However, fewer transits will be required for short-period planets that may be found around bright stars in the TESS and PLATO survey missions. The unprecedented precisions expected from PLATO and JWST will permit the detection of shape deformation with a single transit observation. However, the effects of instrumental and astrophysical noise must be considered as they can increase the number of transits required to reach the 50 ppm min-1 detection limit. We also show that improper modeling of limb darkening can act to bury signals related to the shape of the planet, thereby leading us to infer sphericity for a deformed planet. Accurate determination of the limb darkening coefficients is therefore required to confirm planet deformation.

Bibcode:

2018A&A...620A.203M

Authors:

Moya, A.; Barceló Forteza, S.; Bonfanti, A.; Salmon, S. J. A. J.; Van Grootel, V.; Barrado, D.

Publication:

Astronomy & Astrophysics, Volume 620, id.A203, 14 pp.

Date

2018 November

Abstract:

Context. Asteroseismology has been impressively boosted during the last decade mainly thanks to space missions such as Kepler/K2 and CoRoT. This has a large impact, in particular, in exoplanetary sciences since the accurate characterization of the exoplanets is convoluted in most cases with the characterization of their hosting star. In the decade before the expected launch of the ESA mission PLATO 2.0, only two important missions will provide short-cadence high-precision photometric time-series: NASA-TESS and ESA-CHEOPS missions, both having high capabilities for exoplanetary sciences.
Aims: In this work we want to explore the asteroseismic potential of CHEOPS time-series.
Methods: Following the works estimating the asteroseismic potential of Kepler and TESS, we have analyse...

Context. Asteroseismology has been impressively boosted during the last decade mainly thanks to space missions such as Kepler/K2 and CoRoT. This has a large impact, in particular, in exoplanetary sciences since the accurate characterization of the exoplanets is convoluted in most cases with the characterization of their hosting star. In the decade before the expected launch of the ESA mission PLATO 2.0, only two important missions will provide short-cadence high-precision photometric time-series: NASA-TESS and ESA-CHEOPS missions, both having high capabilities for exoplanetary sciences.
Aims: In this work we want to explore the asteroseismic potential of CHEOPS time-series.
Methods: Following the works estimating the asteroseismic potential of Kepler and TESS, we have analysed the probability of detecting solar-like pulsations using CHEOPS light-curves. Since CHEOPS will collect runs with observational times from hours up to a few days, we have analysed the accuracy and precision we can obtain for the estimation of νmax. This is the only asteroseismic observable we can recover using CHEOPS observations. Finally, we have analysed the impact of knowing νmax in the characterization of exoplanet host stars.
Results: Using CHEOPS light-curves with the expected observational times we can determine νmax for massive G and F-type stars from late main sequence (MS) on, and for F, G, and K-type stars from post-main sequence on with an uncertainty lower than a 5%. For magnitudes V < 12 and observational times from eight hours up to two days, the HR zone of potential detectability changes. The determination of νmax leads to an internal age uncertainty reduction in the characterization of exoplanet host stars from 52% to 38%; mass uncertainty reduction from 2.1% to 1.8%; radius uncertainty reduction from 1.8% to 1.6%; density uncertainty reduction from 5.6% to 4.7%, in our best scenarios.

Bibcode:

https://orbi.uliege.be/handle/2268/229987

Authors:

Plesseria, Jean-Yves; Marquet, Benoit; Mazy, Emmanuel; Clermont, Lionel; Mazzoli, Alexandra; Telle, Alexander

Publication:

Date

2018 September

Abstract:

Black coatings proposed by the company Acktar present very high light absorbance in a broad wavelength range (13 nm to 14 µm). Various types exist presenting their own advantages and characteristics. For 2 separate projects, CSL implemented the Fractal Black™ coating from Acktar on flight hardware in order to reach the expected straylight suppression performances. The first project is the S1 mission of the European Space Agency named CHEOPS. This instrument is observing exoplanets via the transit method in order to determine with high accuracy their characteristics. The small telescope is protected from straylight by a baffle, whose design and manufacturing are under responsibility of CSL. In order to reach the high suppression requirement, the Fractal Black™ coating by Acktar was sel...

Black coatings proposed by the company Acktar present very high light absorbance in a broad wavelength range (13 nm to 14 µm). Various types exist presenting their own advantages and characteristics. For 2 separate projects, CSL implemented the Fractal Black™ coating from Acktar on flight hardware in order to reach the expected straylight suppression performances. The first project is the S1 mission of the European Space Agency named CHEOPS. This instrument is observing exoplanets via the transit method in order to determine with high accuracy their characteristics. The small telescope is protected from straylight by a baffle, whose design and manufacturing are under responsibility of CSL. In order to reach the high suppression requirement, the Fractal Black™ coating by Acktar was selected as blackening solution for some of the internal surfaces. The size and the presence of a sharp edge challenged the provider but excellent results were achieved. In the frame of this project, samples have been coated and several optical measurements have been performed. Rapid thermal cycling and adhesion tests have also been performed on edge samples in order to confirm the coating adhesion in thermal environment. All these results will be presented in the paper. This baffle has passed all qualification steps at subsystem level and instrument level. CHEOPS will be ready for launch end 2018. The second instrument is the embedded calibration assembly of the UVN instrument of Sentinel-4. Sentinel-4 is part of the Copernicus programme of the European Space Agency that will observe from space the atmosphere pollutants. The calibration assembly, which is under responsibility of CSL, will provide calibration references of the instrument at regular intervals. The reference is obtained from sun-light scattered by a stack of diffusers and illuminating the instrument. The calibration system is preceded by a baffle that should attenuate the stray-light from external sources and mainly Earth limb that will be close to the field of view. On the other hand, it shall avoid any impact of the baffle to the absolute transmission of the diffusers and so it shall reject the light from the Sun which will inevitably scatter inside the baffle. Straylight analyses performed at CSL showed that if a large part of the baffle can use classical black coatings, the last conical sections as well as the diffusers holders need to be darker. Different coatings were considered but Fractal Black™ was again a better candidate for this purpose and this solution was selected. The coating was applied by Acktar on these parts. A first qualification model was submitted, among others, to a straylight test which confirms the rejection performance of the overall assembly. The full qualification campaign has also been run successfully on the calibration assembly and acceptance test are completed on 2 flight models. The results of the straylight analyses and of the straylight tests on various models will be presented in the paper.

Bibcode:

2018A&A...616A..39M

Authors:

Maxted, P. F. L.

Publication:

Astronomy & Astrophysics, Volume 616, id.A39, 13 pp.

Date

2018 July

Abstract:

Context. Inaccurate limb-darkening models can be a significant source of error in the analysis of the light curves for transiting exoplanet and eclipsing binary star systems, particularly for high-precision light curves at optical wavelengths. The power-2 limb-darkening law, Iλ(µ) = 1 - c(1-µα), has recently been proposed as a good compromise between complexity and precision in the treatment of limb-darkening.
Aims: My aim is to develop a practical implementation of the power-2 limb-darkening law and to quantify the accuracy of this implementation.
Methods: I have used synthetic spectra based on the 3D stellar atmosphere models from the STAGGER-grid to compute the limb-darkening for several passbands (UBVRI, CHEOPS, TESS, Kepler, etc.). The parameter...

Context. Inaccurate limb-darkening models can be a significant source of error in the analysis of the light curves for transiting exoplanet and eclipsing binary star systems, particularly for high-precision light curves at optical wavelengths. The power-2 limb-darkening law, Iλ(µ) = 1 - c(1-µα), has recently been proposed as a good compromise between complexity and precision in the treatment of limb-darkening.
Aims: My aim is to develop a practical implementation of the power-2 limb-darkening law and to quantify the accuracy of this implementation.
Methods: I have used synthetic spectra based on the 3D stellar atmosphere models from the STAGGER-grid to compute the limb-darkening for several passbands (UBVRI, CHEOPS, TESS, Kepler, etc.). The parameters of the power-2 limb-darkening laws are optimized using a least-squares fit to a simulated light curve computed directly from the tabulated Iλ(μ) values. I use the transformed parameters h1 = 1 - c(1 - 2) and h2 = c2 to directly compare these optimized limb-darkening parameters to the limb darkening measured from Kepler light curves of 16 transiting exoplanet systems.
Results: The posterior probability distributions (PPDs) of the transformed parameters h1 and h2 resulting from the light curve analysis are found to be much less strongly correlated than the PPDs for c and α. The agreement between the computed and observed values of (h1, h2) is generally very good but there are significant differences between the observed and computed values for Kepler-17, the only star in the sample that shows significant variability between the eclipses due to magnetic activity (star spots).
Conclusions: The tabulation of h1 and h2 provided here can be used to accurately model the light curves of transiting exoplanets. I also provide estimates of the priors that should be applied to transformed parameters h1 and h2 based on my analysis of the Kepler light curves of 16 stars with transiting exoplanets. Tables 1 and 2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/616/A39

Bibcode:

2018cosp...42E.345B

Authors:

Billot, Nicolas

Publication:

42nd COSPAR Scientific Assembly. Held 14-22 July 2018, in Pasadena, California, USA, Abstract id. E4.1-6-18.

Date

2018 June

Abstract:

A partnership between Switzerland and the Science Programme of the European Space Agency (ESA), the CHaracterising ExOplanet Satellite (CHEOPS) is ESA's first mission of the recently created S-Class type. CHEOPS will be launch-ready by the end of 2018, and it will be launched from Kourou's spaceport as co-passenger on-board a Soyuz rocket.With its effective mirror size of 30 cm and its remarkable photometric precision of ̃20 ppm (over 6 hours), CHEOPS will be able to measure the bulk density of exoplanets known to transit bright host stars (Vmag = 6-12), thus providing suitable targets for spectroscopic follow-ups with space- or ground-based observatories like e.g. the JWST or the E-ELT. The CHEOPS Mission Consortium, under the leadership of the University of Bern, holds 80% of the observ...

A partnership between Switzerland and the Science Programme of the European Space Agency (ESA), the CHaracterising ExOplanet Satellite (CHEOPS) is ESA's first mission of the recently created S-Class type. CHEOPS will be launch-ready by the end of 2018, and it will be launched from Kourou's spaceport as co-passenger on-board a Soyuz rocket.With its effective mirror size of 30 cm and its remarkable photometric precision of ̃20 ppm (over 6 hours), CHEOPS will be able to measure the bulk density of exoplanets known to transit bright host stars (Vmag = 6-12), thus providing suitable targets for spectroscopic follow-ups with space- or ground-based observatories like e.g. the JWST or the E-ELT. The CHEOPS Mission Consortium, under the leadership of the University of Bern, holds 80% of the observing time, with the remaining 20% being opened to the international community through ESA yearly Announcements of Opportunities (AO). The ESA AO is foreseen for summer 2018, and, by the time of the COSPAR meeting, the Guaranteed Time observing program will have been consolidated already.Unlike other larger ESA missions, the development and operation of the CHEOPS Mission Operations Centre (MOC) and the Science Operations Centre (SOC) are under the responsibility of the Mission Consortium. The University of Geneva is hosting the SOC, where we will run science operations, including the phase-2 submission proposal handling, the mission planning, and the data processing, archiving and dissemination activities. The SOC will deliver science-ready data products through the CHEOPS archive, and all proprietary data will become public one year after their observation for the wider community to access.In this contribution, we will present the CHEOPS Science Operations concept and its implementation at the Geneva Observatory. We will present all SOC activities, and in particular the challenging task of optimising the schedule of hundreds of time-critical observations making use of genetic algorithms.

Bibcode:

2018SPIE10698E..3BM

Authors:

Magrin, Demetrio; Viotto, Valentina; Beck, Thomas; Bruno, Giordano; Baroni, Marco; Turella, Andrea; Marinai, Massimo; Bergomi, Maria; Biondi, Federico; Munari, Matteo; Marafatto, Luca; Farinato, Jacopo; Greggio, Davide; Dima, Marco; Scandariato, Gaetano; Pagano, Isabella; Ragazzoni, Roberto; Rieder, Martin; Busch, Martin Diego; Piazza, Daniele; Bandy, Timothy; Broeg, Christopher; Fortier, Andrea; Hernandez, Eduardo; Cessa, Virginie; Benz, Willy; Piotto, Giampaolo; Giannuzzo, Ester; Dami, Michele; Battistelli, Enrico; Salatti, Mario; Tommasi, Elisabetta; De Angelis, Luigi; Deep, Atul; Ngan, Ivan; Ratti, Francesco; Gambicorti, Lisa; Rando, Nicola

Publication:

Proceedings of the SPIE, Volume 10698, id. 106983B 8 pp. (2018).

Copyright ©

(c) 2018: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2018 June

Abstract:

CHEOPS is the first small class mission adopted by ESA in the framework of the Cosmic Vision 2015-2025. Its launch is foreseen in early 2019. CHEOPS aims to get transits follow-up measurements of already known exo-planets, hosted by near bright stars (V<12). Thanks to its ultra-high precision photometry, CHEOPS science goal is accurately measure the radii of planets in the super-Earth to Neptune mass range (1<Mplanet/MEarth<20). The knowledge of the radius by transit measurements, combined with the determination of planet mass through radial velocity techniques, will allow the determination/refinement of the bulk density for a large number of small planets during the scheduled 3.5 years life mission. The instrument is mainly composed of a 320 mm aperture diameter Ritchey-Chretien ...

CHEOPS is the first small class mission adopted by ESA in the framework of the Cosmic Vision 2015-2025. Its launch is foreseen in early 2019. CHEOPS aims to get transits follow-up measurements of already known exo-planets, hosted by near bright stars (V<12). Thanks to its ultra-high precision photometry, CHEOPS science goal is accurately measure the radii of planets in the super-Earth to Neptune mass range (1<Mplanet/MEarth<20). The knowledge of the radius by transit measurements, combined with the determination of planet mass through radial velocity techniques, will allow the determination/refinement of the bulk density for a large number of small planets during the scheduled 3.5 years life mission. The instrument is mainly composed of a 320 mm aperture diameter Ritchey-Chretien telescope and a Back End Optics, delivering a de-focused star image onto the focal plane. In this paper we describe the opto-thermo-mechanical model of the instrument and the measurements obtained during the opto-mechanical integration and alignment phase at Leonardo company premises, highlighting the level of congruence between the predictions and measurements.

Bibcode:

2018SPIE10698E..0KR

Authors:

Rando, N.; Asquier, J.; Corral Van Damme, C.; Isaak, K.; Ratti, F.; Verhoeve, P.; Safa, F.; Southworth, R.; Broeg, C.; Benz, W.

Publication:

Proceedings of the SPIE, Volume 10698, id. 106980K 14 pp. (2018).

Copyright ©

(c) 2018: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2018 June

Abstract:

The ESA Science Programme Committee (SPC) selected CHEOPS (Characterizing Exoplanets Satellite) in October 2012 as the first Small-class mission (S1) within the Agency's Scientific Programme, with the following requirements: science driven mission selected through an open Call; an implementation cycle, from the Call to launch, drastically shorter than for Medium-class (M) and Large-class (L) missions; a strict cost-cap to ESA, with possibly higher Member States involvement than for M or L missions. The CHEOPS mission is devoted to the characterization of known exoplanets orbiting bright stars, achieved through the precise measurement of exoplanet radii using the technique of transit photometry. It was adopted for implementation in February 2014 as a partnership between the ESA Science Prog...

The ESA Science Programme Committee (SPC) selected CHEOPS (Characterizing Exoplanets Satellite) in October 2012 as the first Small-class mission (S1) within the Agency's Scientific Programme, with the following requirements: science driven mission selected through an open Call; an implementation cycle, from the Call to launch, drastically shorter than for Medium-class (M) and Large-class (L) missions; a strict cost-cap to ESA, with possibly higher Member States involvement than for M or L missions. The CHEOPS mission is devoted to the characterization of known exoplanets orbiting bright stars, achieved through the precise measurement of exoplanet radii using the technique of transit photometry. It was adopted for implementation in February 2014 as a partnership between the ESA Science Programme and Switzerland, with a number of other Member States delivering significant contributions to the instrument development and to operations. The CHEOPS instrument is an optical Ritchey-Chrétien telescope with 300 mm effective aperture diameter and a large external baffle to minimize straylight. The compact CHEOPS spacecraft (approx. 300 kg, 1.5 m size), based on a flight-proven platform, will orbit the Earth in a dawn-dusk Sun Synchronous Orbit at 700 km altitude. CHEOPS completed the Preliminary Design Review at the end of September 2014, and passed the Critical Design Review in May 2016. In the course of 2017, flight platform and payload have been integrated and tested, while satellite level activities are planned to start in early 2018, targeting flight readiness by the end of the year. The paper describes the latest CHEOPS development status, focusing on the acceptance test performed on instrument and platform, as well as on the satellite level environmental test campaign.

Bibcode:

2018cosp...42E.438B

Authors:

Broeg, Christopher; Benz, Willy; Fortier, Andrea

Publication:

42nd COSPAR Scientific Assembly. Held 14-22 July 2018, in Pasadena, California, USA, Abstract id. E4.1-5-18.

Date

2018 June

Abstract:

The CHaracterising ExOPlanet Satellite (CHEOPS) is a mission jointly led by Switzerland and ESA which was selected in October 2012 as the first small-class mission in the ESA Science Programme. CHEOPS will be the first space observatory dedicated to search for transits of exoplanets by means of ultrahigh precision photometry on bright stars already known to host planets. The CHEOPS telescope will have access to more than 70% of the sky, which will provide the unique capability of determining accurate radii for planets for which the mass has already been estimated from ground-based spectroscopic surveys. This, in turn, will allow a first order characterisation of the planets' internal structure (i.e. the determination of the mean density, which provides direct insights into its composition)...

The CHaracterising ExOPlanet Satellite (CHEOPS) is a mission jointly led by Switzerland and ESA which was selected in October 2012 as the first small-class mission in the ESA Science Programme. CHEOPS will be the first space observatory dedicated to search for transits of exoplanets by means of ultrahigh precision photometry on bright stars already known to host planets. The CHEOPS telescope will have access to more than 70% of the sky, which will provide the unique capability of determining accurate radii for planets for which the mass has already been estimated from ground-based spectroscopic surveys. This, in turn, will allow a first order characterisation of the planets' internal structure (i.e. the determination of the mean density, which provides direct insights into its composition). CHEOPS will also provide precise radii for new planets discovered by the next generation of ground- or space-based transits surveys.To reach its goals, CHEOPS is designed to measure photometric signals with a precision of 20 ppm in 6 hours of integration time for a 9th magnitude star and 85 ppm in 3 hours of integration for a 12th magnitude star. The CHEOPS payload consists in a single instrument, a space telescope of 30 cm clear aperture, which has a single CCD focal plane detector. The optical configuration consists of a Ritchey-Chrétien telescope, which provides a defocussed image of the target star on the focal plane. The main design drivers are related to the compactness of the optical system and to the capability to reject the stray light.The nominal CHEOPS operational orbit is a polar Sun-synchronous orbit (SSO) with an altitude of 700 km and a local time of the ascending node (LTAN) of 6 am; the orbit inclination is about 98° and the orbital period is 100 min.The nominal mission lifetime is 3.5 years, with a possible extension to a total of 5 years enabled by appropriate sizing of the consumables budget. The target launch date is end of 2018.With the launch coming up in less than a year, the instrument is already fully assembled and tested and the final steps for its delivery to the spacecraft premises are ongoing. This paper will review the scientific goals of the mission in combination with the expected performance of the instrument, the latter derived from the latest measurements taken during the calibration campaign.

Bibcode:

2018MNRAS.475.3090Y

Authors:

Yi, Joo Sung; Chen, Jingjing; Kipping, David

Publication:

Monthly Notices of the Royal Astronomical Society, Volume 475, Issue 3, p.3090-3097

Copyright ©

2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Date

2018 March

Abstract:

The CHaracterizing ExOPlanets Satellite (CHEOPS) mission is planned for launch next year with a major objective being to search for transits of known radial velocity (RV) planets, particularly those orbiting bright stars. Since the RV method is only sensitive to planetary mass, the radii, transit depths and transit signal-to-noise values of each RV planet are, a priori, unknown. Using an empirically calibrated probabilistic mass-radius relation, forecaster, we address this by predicting a catalogue of homogeneous credible intervals for these three keys terms for 468 planets discovered via RVs. Of these, we find that the vast majority should be detectable with CHEOPS, including terrestrial bodies, if they have the correct geometric alignment. In particular, we predict that 22 mini-Neptunes ...

The CHaracterizing ExOPlanets Satellite (CHEOPS) mission is planned for launch next year with a major objective being to search for transits of known radial velocity (RV) planets, particularly those orbiting bright stars. Since the RV method is only sensitive to planetary mass, the radii, transit depths and transit signal-to-noise values of each RV planet are, a priori, unknown. Using an empirically calibrated probabilistic mass-radius relation, forecaster, we address this by predicting a catalogue of homogeneous credible intervals for these three keys terms for 468 planets discovered via RVs. Of these, we find that the vast majority should be detectable with CHEOPS, including terrestrial bodies, if they have the correct geometric alignment. In particular, we predict that 22 mini-Neptunes and 82 Neptune-sized planets would be suitable for detection and that more than 80 per cent of these will have apparent magnitude of V < 10, making them highly suitable for follow-up characterization work. Our work aims to assist the CHEOPS team in scheduling efforts and highlights the great value of quantifiable, statistically robust estimates for upcoming exoplanetary missions.

Bibcode:

2018A&A...611A…8S

Authors:

Serrano, L. M.; Barros, S. C. C.; Oshagh, M.; Santos, N. C.; Faria, J. P.; Demangeon, O.; Sousa, S. G.; Lendl, M.

Publication:

Astronomy & Astrophysics, Volume 611, id.A8, 14 pp.

Date

2018 February

Abstract:

Context. Light curves show the flux variation from the target star and its orbiting planets as a function of time. In addition to the transit features created by the planets, the flux also includes the reflected light component of each planet, which depends on the planetary albedo. This signal is typically referred to as phase curve and could be easily identified if there were no additional noise. As well as instrumental noise, stellar activity, such as spots, can create a modulation in the data, which may be very difficult to distinguish from the planetary signal.
Aims: We analyze the limitations imposed by the stellar activity on the detection of the planetary albedo, considering the limitations imposed by the predicted level of instrumental noise and the short duration of the obe...

Context. Light curves show the flux variation from the target star and its orbiting planets as a function of time. In addition to the transit features created by the planets, the flux also includes the reflected light component of each planet, which depends on the planetary albedo. This signal is typically referred to as phase curve and could be easily identified if there were no additional noise. As well as instrumental noise, stellar activity, such as spots, can create a modulation in the data, which may be very difficult to distinguish from the planetary signal.
Aims: We analyze the limitations imposed by the stellar activity on the detection of the planetary albedo, considering the limitations imposed by the predicted level of instrumental noise and the short duration of the obervations planned in the context of the CHEOPS mission.
Methods: As initial condition, we have assumed that each star is characterized by just one orbiting planet. We built mock light curves that included a realistic stellar activity pattern, the reflected light component of the planet and an instrumental noise level, which we have chosen to be at the same level as predicted for CHEOPS. We then fit these light curves to try to recover the reflected light component, assuming the activity patterns can be modeled with a Gaussian process.
Results: We estimate that at least one full stellar rotation is necessary to obtain a reliable detection of the planetary albedo. This result is independent of the level of noise, but it depends on the limitation of the Gaussian process to describe the stellar activity when the light curve time-span is shorter than the stellar rotation. As an additional result, we found that with a 6.5 magnitude star and the noise level of CHEOPS, it is possible to detect the planetary albedo up to a lower limit of Rp = 0.03 R*. Finally, in presence of typical CHEOPS gaps in the simulations, we confirm that it is still possible to obtain a reliable albedo.

Bibcode:

2018A&A...609A..21A

Authors:

Akinsanmi, B.; Oshagh, M.; Santos, N. C.; Barros, S. C. C.

Publication:

Astronomy & Astrophysics, Volume 609, id.A21, 13 pp.

Date

2017 December

Abstract:

Context. It is theoretically possible for rings to have formed around extrasolar planets in a similar way to that in which they formed around the giant planets in our solar system. However, no such rings have been detected to date.
Aims: We aim to test the possibility of detecting rings around exoplanets by investigating the photometric and spectroscopic ring signatures in high-precision transit signals.
Methods: The photometric and spectroscopic transit signals of a ringed planet is expected to show deviations from that of a spherical planet. We used these deviations to quantify the detectability of rings. We present SOAP3.0 which is a numerical tool to simulate ringed planet transits and measure ring detectability based on amplitudes of the residuals between the ringed plan...

Context. It is theoretically possible for rings to have formed around extrasolar planets in a similar way to that in which they formed around the giant planets in our solar system. However, no such rings have been detected to date.
Aims: We aim to test the possibility of detecting rings around exoplanets by investigating the photometric and spectroscopic ring signatures in high-precision transit signals.
Methods: The photometric and spectroscopic transit signals of a ringed planet is expected to show deviations from that of a spherical planet. We used these deviations to quantify the detectability of rings. We present SOAP3.0 which is a numerical tool to simulate ringed planet transits and measure ring detectability based on amplitudes of the residuals between the ringed planet signal and best fit ringless model.
Results: We find that it is possible to detect the photometric and spectroscopic signature of near edge-on rings especially around planets with high impact parameter. Time resolution ≤7 min is required for the photometric detection, while 15 min is sufficient for the spectroscopic detection. We also show that future instruments like CHEOPS and ESPRESSO, with precisions that allow ring signatures to be well above their noise-level, present good prospects for detecting rings.

Bibcode:

2017SPIE10563E..1LC

Authors:

Cessa, V.; Beck, T.; Benz, W.; Broeg, C.; Ehrenreich, D.; Fortier, A.; Peter, G.; Magrin, D.; Pagano, I.; Plesseria, J. -Y.; Steller, M.; Szoke, J.; Thomas, N.; Ragazzoni, R.; Wildi, F.

Publication:

Proceedings of the SPIE, Volume 10563, id. 105631L 9 pp. (2017).

Copyright ©

(c) 2017: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2017 October

Abstract:

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultra-high precision photometry whose launch readiness is expected end 2017. The CHEOPS instrument will be the first space telescope dedicated to search for transits on bright stars already known to host planets. By being able to point at nearly any location on the sky, it will provide the unique capability of determining accurate radii for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys. CHEOPS will also provide precision radii for new planets discovered by the next generation ground-based transits surveys (Neptune-size and smaller). The main science goals of the CHEOPS mission will b...

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultra-high precision photometry whose launch readiness is expected end 2017. The CHEOPS instrument will be the first space telescope dedicated to search for transits on bright stars already known to host planets. By being able to point at nearly any location on the sky, it will provide the unique capability of determining accurate radii for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys. CHEOPS will also provide precision radii for new planets discovered by the next generation ground-based transits surveys (Neptune-size and smaller). The main science goals of the CHEOPS mission will be to study the structure of exoplanets with radii typically ranging from 1 to 6 Earth radii orbiting bright stars. With an accurate knowledge of masses and radii for an unprecedented sample of planets, CHEOPS will set new constraints on the structure and hence on the formation and evolution of planets in this mass range. To reach its goals CHEOPS will measure photometric signals with a precision of 20 ppm in 6 hours of integration time for a 9th magnitude star. This corresponds to a signal to noise of 5 for a transit of an Earth-sized planet orbiting a solar-sized star (0.9 solar radii). This precision will be achieved by using a single frame-transfer backside illuminated CCD detector cool down at 233K and stabilized within {10 mK . The CHEOPS optical design is based on a Ritchey-Chretien style telescope with 300 mm effective aperture diameter, which provides a defocussed image of the target star while minimizing straylight using a dedicated field stop and baffle system. As CHEOPS will be in a LEO orbit, straylight suppression is a key point to allow the observation of faint stars. The telescope will be the only payload on a spacecraft platform providing pointing stability of < 8 arcsec rms, power of 60W for instrument operations and downlink transmission of at least 1.2GBit/day. Both CHEOPS paylaod and platform will rely mainly on components with flight heritage. The baseline CHEOPS mission fits within the technical readiness requirements, short development time and the cost envelope defined by ESA in its first call for S-missions. It represents a breakthrough opportunity in furthering our understanding of the formation and evolution of planetary systems.

Bibcode:

2017SPIE10562E..18B

Authors:

Beck, T.; Gambicorti, L.; Broeg, C.; Cessa, V.; Fortier, A.; Piazza, D.; Ehrenreich, D.; Magrin, D.; Plesseria, J. Y.; Peter, G.; Pagano, I.; Steller, M.; Kovacs, Z.; Ragazzoni, R.; Wildi, F.; Benz, W.

Publication:

Proceedings of the SPIE, Volume 10562, id. 1056218 8 pp. (2017).

Copyright ©

(c) 2017: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2017 August

Abstract:

CHEOPS (CHaracterising ExOPlanet Satellite) is the first ESA Small Mission as part of the ESA Cosmic Vision program 2015-2025 and it is planned launch readiness end of 2017. The mission lead is performed in a partnership between Switzerland, led by the University of Bern, and the European Space Agency with important contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS mission will be the first space telescope dedicated to search for exoplanetary transits on bright stars already known to host planets by performing ultrahigh precision photometry on bright starts whose mass has been already estimated through spectroscopic surveys on ground based observations. The number of exoplanets in the mass range 1-30 MEarth for...

CHEOPS (CHaracterising ExOPlanet Satellite) is the first ESA Small Mission as part of the ESA Cosmic Vision program 2015-2025 and it is planned launch readiness end of 2017. The mission lead is performed in a partnership between Switzerland, led by the University of Bern, and the European Space Agency with important contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS mission will be the first space telescope dedicated to search for exoplanetary transits on bright stars already known to host planets by performing ultrahigh precision photometry on bright starts whose mass has been already estimated through spectroscopic surveys on ground based observations. The number of exoplanets in the mass range 1-30 MEarth for which both mass and radius are known with a good precision is extremely limited also considering the last two decades of high-precision radial velocity measurement campaigns and the highly successful space missions dedicated to exoplanets transit searches (CoRoT and Kepler).

Bibcode:

2017MNRAS.468.3418G

Authors:

Gaidos, E.; Kitzmann, D.; Heng, K.

Publication:

Monthly Notices of the Royal Astronomical Society, Volume 468, Issue 3, p.3418-3427

Copyright ©

2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Date

2017 June

Abstract:

Space-based photometric surveys have discovered large numbers of planets transiting other stars, but these observe in a single band-pass and yield only the planet radius, orbital period and transit duration. Information on the masses, compositions and any atmospheres of these planets requires additional observations from the ground or space. The Transiting Exoplanet Survey Satellite (TESS) will yield thousands of planets around bright stars suitable for such follow-up. In the absence of spectroscopy or spectrophotometry from space, observations through the different passbands of multiple space telescopes provide some spectral information useful for identifying false-positive signals, distinguishing between reflected light and thermal emission from hot Jupiters, and detecting Rayleigh scatt...

Space-based photometric surveys have discovered large numbers of planets transiting other stars, but these observe in a single band-pass and yield only the planet radius, orbital period and transit duration. Information on the masses, compositions and any atmospheres of these planets requires additional observations from the ground or space. The Transiting Exoplanet Survey Satellite (TESS) will yield thousands of planets around bright stars suitable for such follow-up. In the absence of spectroscopy or spectrophotometry from space, observations through the different passbands of multiple space telescopes provide some spectral information useful for identifying false-positive signals, distinguishing between reflected light and thermal emission from hot Jupiters, and detecting Rayleigh scattering by planetary atmospheres. We calculated the expected difference in transit depths measured by the TESS and Characterizing Exoplanet Satellite (CHEOPS) missions, which will be more sensitive to redder and bluer optical wavelengths, respectively. The difference due to companion or background stars is small (<3 per cent for main-sequence companions) and likely to be negligible and undetectable. For only a few 'hot' Jupiters, can combined photometry disambiguate between the reflected and thermal signals from planets. However, the Rayleigh scattering by hazy atmospheres with particles sizes near 0.04 μm and at pressure altitudes above ̃1 mbar can be detected for ̃100 transiting planets, assuming every planet has such an atmosphere. Hazes with this characteristic particle size do not obscure observations at longer (near-infrared) wavelengths; CHEOPS follow-up of TESS-detected planets could thus identify candidates suitable for further study with the James Webb Space Telescope.

Bibcode:

2016SPIE.9912E..1GB

Authors:

Blecha, L.; Zindel, D.; Cottard, H.; Beck, T.; Cessa, V.; Broeg, C.; Ratti, F.; Rando, N.

Publication:

Proceedings of the SPIE, Volume 9912, id. 99121G 9 pp. (2016).

Copyright ©

(c) 2016: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2016 June

Abstract:

The CHEOPS (CHaracterising ExOPlanet Satellite), which is an ESA mission developed in cooperation with Switzerland and a number of other member-states, is the first one dedicated to search for transits by means of ultrahigh precision photometry on bright stars already known to host planets. The optical design is based on a Ritchey-Chretien style telescope to provide a de-focussed image of the target stars. The telescope's mirrors M1, M2 as well as the focal plane detector are supported by a thermally controlled CFRP structure suspended on isostatic mounts. The dimensional stability of the structural system supporting the optics is a key requirement as it directly impacts the instrument's accuracy. The M1 and M2 mirrors are supported by a tubular CFRP telescope design which has been optimiz...

The CHEOPS (CHaracterising ExOPlanet Satellite), which is an ESA mission developed in cooperation with Switzerland and a number of other member-states, is the first one dedicated to search for transits by means of ultrahigh precision photometry on bright stars already known to host planets. The optical design is based on a Ritchey-Chretien style telescope to provide a de-focussed image of the target stars. The telescope's mirrors M1, M2 as well as the focal plane detector are supported by a thermally controlled CFRP structure suspended on isostatic mounts. The dimensional stability of the structural system supporting the optics is a key requirement as it directly impacts the instrument's accuracy. The M1 and M2 mirrors are supported by a tubular CFRP telescope design which has been optimized by analyses down to carbon fibre layer level with the support of extensive sample test results for model correlation and accurate dimensional stability predictions. This sample characterization test campaign has been conducted on samples with different carbon fibre layups (orientation and stack sequence) to measure accurately the Coefficient of Thermal Expansion (CTE) over a wide temperature range extending from -80°C to +80°C. Using the correlated Finite Element Model, the fibre orientation layup that minimized the relative displacement between the M1 and M2 mirrors, including the consideration of the thermo-elastic contributions of the isostatic mounts on the overall stability of this optical system, has been identified and selected for the baseline design of the CHEOPS Structure. A dedicated Structural and Thermal Model (STM2), which was then refurbished to a PFM, was manufactured and tested with an ad hoc setup to verify the overall structural stability of the optical train assembly [2]. The relative distance between M1 and M2 was measured under thermal vacuum conditions using laser interferometer techniques. Thermal cycling tests were initially conducted to eliminate and characterize settling effects. Then, the structure's stability was measured at three stabilised operational temperatures: -5, -10 and -15°C. The thermally induced M1-M2 misalignment on the optical axis was measured to be between -0.156 and -0.168 micron/°C. Relative mirror tilt and lateral centre shifts were also measured. The obtained focal distance, tilt and centre shift stability between mirrors M1 and M2 were all compliant with the system level requirements such that both an STM and PFM model of the CHEOPS CFRP Structure were successfully qualified and delivered in due time for integration on the spacecraft.

Bibcode:

2016SPIE.9904E..2AB

Authors:

Beck, T.; Broeg, C.; Fortier, A.; Cessa, V.; Malvasio, L.; Piazza, D.; Benz, W.; Thomas, N.; Magrin, D.; Viotto, V.; Bergomi, M.; Ragazzoni, R.; Pagano, I.; Peter, G.; Buder, M.; Plesseria, J. Y.; Steller, M.; Ottensamer, R.; Ehrenreich, D.; Van Damme, C.; Isaak, K.; Ratti, F.; Rando, N.; Ngan, I.

Publication:

Proceedings of the SPIE, Volume 9904, id. 99042A 16 pp. (2016).

Copyright ©

(c) 2016: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2016 June

Abstract:

CHEOPS (CHaracterizing ExOPlanets Satellite) is the first ESA Small Mission as part of the ESA Cosmic Vision program 2015-2025. The mission was formally adopted in early February 2014 with a planned launch readiness end of 2017. The mission lead is performed in a partnership between Switzerland, led by the University of Bern, and the European Space Agency with important contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The mission is dedicated to searching for exoplanetary transits by performing ultrahigh precision photometry on bright starts already known to host planets whose mass has been already estimated through ground based observations. The instrument is an optical Ritchey-Chretien telescope of 30 cm clear aperture...

CHEOPS (CHaracterizing ExOPlanets Satellite) is the first ESA Small Mission as part of the ESA Cosmic Vision program 2015-2025. The mission was formally adopted in early February 2014 with a planned launch readiness end of 2017. The mission lead is performed in a partnership between Switzerland, led by the University of Bern, and the European Space Agency with important contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The mission is dedicated to searching for exoplanetary transits by performing ultrahigh precision photometry on bright starts already known to host planets whose mass has been already estimated through ground based observations. The instrument is an optical Ritchey-Chretien telescope of 30 cm clear aperture using a single CCD detector. The optical system is designed to image a de-focused PSF onto the focal plane with very stringent stability and straylight rejection requirements providing a FoV of 0.32 degrees full cone. The system design is adapted to meet the top-level science requirements, which ask for a photometric precision of 20ppm, in 6 hours integration time, on transit measurements of G5 dwarf stars with V-band magnitudes in the range 6≤V≤9 mag. Additionally they ask for a photometric precision of 85 ppm in 3 hours integration time of Neptune-size planets transiting K-type dwarf stars with V-band magnitudes as faint as V=12 mag. Given the demanding schedule and cost constrains, the mission relies mostly on components with flight heritage for the platform as well as for the payload components. Nevertheless, several new developments are integrated into the design as for example the telescope structure and the very low noise, high stability CCD front end electronics. The instrument and mission have gone through critical design review in fall 2015 / spring 2016. This paper describes the current instrument and mission design with a focus on the instrument. It outlines the technical challenges and selected design implementation. Based on the current status, the instrument noise budget is presented including the current best estimate for instrument performance. The current instrument design meets the science requirements and mass and power margins are adequate for the current development status.

Bibcode:

2016SPIE.9913E..2WL

Authors:

Loeschl, P.; Ferstl, R.; Kerschbaum, F.; Ottensamer, R.

Publication:

Proceedings of the SPIE, Volume 9913, id. 99132W 16 pp. (2016).

Copyright ©

(c) 2016: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2016 June

Abstract:

The CHaracterising ExOPlanet Satellite (CHEOPS) is the first ESA S-class and exoplanetary follow-up mission headed for launch in 2018. It will perform ultra-high-precision photometry of stars hosting confirmed exoplanets on a 3-axis stabilised sun-synchronous orbit that is optimised for uninterrupted observations at minimum stray light and thermal variations. Nevertheless, due to the satellites structural design, the alignment of the star trackers and the payload instrument telescope is affected by thermo-elastic deformations. This causes a high pointing uncertainty, which requires the payload instrument to provide an additional acquisition system for distinct target identification. Therefor a star extraction software and two star identification algorithms, originally designed for star tra...

The CHaracterising ExOPlanet Satellite (CHEOPS) is the first ESA S-class and exoplanetary follow-up mission headed for launch in 2018. It will perform ultra-high-precision photometry of stars hosting confirmed exoplanets on a 3-axis stabilised sun-synchronous orbit that is optimised for uninterrupted observations at minimum stray light and thermal variations. Nevertheless, due to the satellites structural design, the alignment of the star trackers and the payload instrument telescope is affected by thermo-elastic deformations. This causes a high pointing uncertainty, which requires the payload instrument to provide an additional acquisition system for distinct target identification. Therefor a star extraction software and two star identification algorithms, originally designed for star trackers, were adapted and optimised for the special case of CHEOPS. In order to evaluate these algorithms reliability, thousands of random star configurations were analysed in Monte-Carlo simulations. We present the implemented identification methods and their performance as well as recommended parameters that guarantee a successful identification under all conditions.

Bibcode:

2016SPIE.9904E..29R

Authors:

Rando, N.; Asquier, J.; Corral Van Damme, C.; Isaak, K.; Ratti, F.; Safa, F.; Southworth, R.; Broeg, C.; Benz, W.

Publication:

Proceedings of the SPIE, Volume 9904, id. 990429 13 pp. (2016).

Copyright ©

(c) 2016: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2016 June

Abstract:

The European Space Agency (ESA) Science Programme Committee (SPC) selected CHEOPS (Characterizing Exoplanets Satellite) in October 2012 as the first S-class mission (S1) within the Agency's Scientific Programme, targeting launch readiness by the end of 2017. The CHEOPS mission is devoted to the first-step characterization of known exoplanets orbiting bright stars, to be achieved through the precise measurement of exo-planet radii using the technique of transit photometry. It is implemented as a partnership between ESA and a consortium of Member States led by Switzerland. CHEOPS is considered as a pilot case for implementing "small science missions" in ESA with the following requirements: science driven missions selected through an open Call for missions (bottom-up process); spacecraft deve...

The European Space Agency (ESA) Science Programme Committee (SPC) selected CHEOPS (Characterizing Exoplanets Satellite) in October 2012 as the first S-class mission (S1) within the Agency's Scientific Programme, targeting launch readiness by the end of 2017. The CHEOPS mission is devoted to the first-step characterization of known exoplanets orbiting bright stars, to be achieved through the precise measurement of exo-planet radii using the technique of transit photometry. It is implemented as a partnership between ESA and a consortium of Member States led by Switzerland. CHEOPS is considered as a pilot case for implementing "small science missions" in ESA with the following requirements: science driven missions selected through an open Call for missions (bottom-up process); spacecraft development schedule much shorter than for M and L missions, in the range of 4 years; and cost-capped missions to ESA with possibly higher Member States involvement than for M or L missions. The paper describes the CHEOPS development status, focusing on the performed hardware manufacturing and test activities.

Bibcode:

2016frap.confE..89S

Authors:

Scandariato, G.; Ehrenreich, D.; Pagano, I.; Queloz, D.; Alibert, Y.; Alonso, R.; Bárczy, T.; Baumjohann, W.; Benz, W.; Bonfils, X.; Brandeker, A.; Borsato, L.; Broeg, C.; Cabrera, J.; Charnoz, S.; Cameron, A. C.; Davies, M.; Demangeon, O.; Deleuil, M.; Erikson, A.; Fortier, A.; Fossati, L.; Fridlund, M.; Gandolfi, D.; Gillon, M.; Güdel, M.; Isaak, K.; Kiss, L.; Laskar, J.; Lovis, C.; Meyer, M. R.; Nascimbeni, V.; Oloffson, G.; Pallé, E.; Piotto, G.; Pollacco, D.; Ragazzoni, R.; Rando, N.; Renottes, É.; Ribas, I.; Santos, N. C.; Sousa, S.; Spohnl, T.; Steller, M.; Szabó, G.; Thomas, N.; Udry, S.; Walton, N.; Barrado y Novascués, D.; Gutierrez Peña, A.; Lecavelier des Etangs, A.; Van Grootel, V.

Publication:

Frontier Research in Astrophysics II, held 23-28 May, 2016 in Mondello (Palermo), Italy (FRAPWS2016). Online at https://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=269, id.89

Date

2016 April

Bibcode:

2015ESS.....350304B

Authors:

Broeg, Christopher; benz, willy; fortier, andrea; Ehrenreich, David; beck, Thomas; cessa, Virginie; Alibert, Yann; Heng, Kevin

Publication:

American Astronomical Society, ESS meeting #3, id.503.04. BAAS volume 47 #6, November 2015.

Copyright ©

(c) 2015: American Astronomical Society

Date

2015 November

Abstract:

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultra-high precision photometry. It is expected to be launch-ready at the end of 2017.CHEOPS will be the first space observatory dedicated to search for transits on bright stars already known to host planets. It will have access to more than 70% of the sky. This will provide the unique capability of determining accurate radii for planets for which the mass has already been estimated from ground-based radial velocity surveys and for new planets discovered by the next generation ground-based transits surveys (Neptune-size and smaller). The measurement of the radius of a planet from its transit combined with the determination of its mass through radia...

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultra-high precision photometry. It is expected to be launch-ready at the end of 2017.CHEOPS will be the first space observatory dedicated to search for transits on bright stars already known to host planets. It will have access to more than 70% of the sky. This will provide the unique capability of determining accurate radii for planets for which the mass has already been estimated from ground-based radial velocity surveys and for new planets discovered by the next generation ground-based transits surveys (Neptune-size and smaller). The measurement of the radius of a planet from its transit combined with the determination of its mass through radial velocity techniques gives the bulk density of the planet, which provides direct insights into the structure and/or composition of the body. In order to meet the scientific objectives, a number of requirements have been derived that drive the design of CHEOPS. For the detection of Earth and super-Earth planets orbiting G5 dwarf stars with V-band magnitudes in the range 6 ≤ V ≤ 9 mag, a photometric precision of 20 ppm in 6 hours of integration time must be reached. This time corresponds to the transit duration of a planet with a revolution period of 50 days. In the case of Neptune-size planets orbiting K-type dwarf with magnitudes as faint as V=12 mag, a photometric precision of 85 ppm in 3 hours of integration time must be reached. To achieve this performance, the CHEOPS mission payload consists of only one instrument, a space telescope of 30 cm clear aperture, which has a single CCD focal plane detector. CHEOPS will be inserted in a low Earth orbit and the total duration of the CHEOPS mission is 3.5 years (goal: 5 years).The presentation will describe the current payload and mission design of CHEOPS, give the development status, and show the expected performances.

Bibcode:

2015ESASP.732E..43C

Authors:

Cechticky, V.; Ottensamer, R.; Pasetti, A.

Publication:

DAta Systems in Aerospace, Proceedings of the conference held 19-21 May, 2015 in Barcelona, Spain. Edited by L. Ouwehand. ESA-SP Vol. 732, 2015, id.43

Date

2015 August

Abstract:

CHEOPS is an ESA S-class mission dedicated to the precise measurement of radii of already known exoplanets using ultra-high precision photometry. The instrument flight software controlling the instrument and handling the science data is developed by the University of Vienna using the CORDET Framework offered by P&P Software GmbH. The CORDET Framework provides a generic software infrastructure for PUS-based applications. This paper describes how the framework is used for the CHEOPS application software to provide a consistent solution for to the communication and control services, event handling and FDIR procedures. This approach is innovative in four respects: (a) it is a true third-party reuse; (b) re-use is done at specification, validation and code level; (c) the re-usable assets an...

CHEOPS is an ESA S-class mission dedicated to the precise measurement of radii of already known exoplanets using ultra-high precision photometry. The instrument flight software controlling the instrument and handling the science data is developed by the University of Vienna using the CORDET Framework offered by P&P Software GmbH. The CORDET Framework provides a generic software infrastructure for PUS-based applications. This paper describes how the framework is used for the CHEOPS application software to provide a consistent solution for to the communication and control services, event handling and FDIR procedures. This approach is innovative in four respects: (a) it is a true third-party reuse; (b) re-use is done at specification, validation and code level; (c) the re-usable assets and their qualification data package are entirely open-source; (d) re-use is based on call-back with the application developer providing functions which are called by the reusable architecture. File names missing from here on out (I tried to mimic the files names from before.)

Bibcode:

2015pthp.confE..76F

Authors:

Fortier, Andrea; Beck, Thomas; Benz, Willy; Broeg, Christopher; Cessa, Virginie; Ehrenreich, David; Ottensamer, Roland; Pagano, Isabella; Peter, Gisbert; Plesseria, Jean-Yves; Ragazzoni, Roberto; Ratti, Francesco; Steller, Manfred; Szoke, Janos

Publication:

Pathways Towards Habitable Planets, Proceedings of a conference held 13-17 July, 2015 in Bern, Switzerland. Online at: https://pathways2015.sciencesconf.org/program, id.76

Date

2015 June

Abstract:

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultra-high precision photometry. It is expected to be launch-ready at the end of 2017. CHEOPS will be the first space observatory dedicated to search for transits on bright stars already known to host planets. It will have access to more than 70% of the sky. This will provide the unique capability of determining accurate radii for planets for which the mass has already been estimated from ground-based spectroscopic surveys and for new planets discovered by the next generation ground-based transits surveys (Neptune-size and smaller). The measurement of the radius of a planet from its transit combined with the determination of its mass through radial...

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultra-high precision photometry. It is expected to be launch-ready at the end of 2017. CHEOPS will be the first space observatory dedicated to search for transits on bright stars already known to host planets. It will have access to more than 70% of the sky. This will provide the unique capability of determining accurate radii for planets for which the mass has already been estimated from ground-based spectroscopic surveys and for new planets discovered by the next generation ground-based transits surveys (Neptune-size and smaller). The measurement of the radius of a planet from its transit combined with the determination of its mass through radial velocity techniques gives the bulk density of the planet, which provides direct insights into the structure and/or composition of the body. In order to meet the scientific objectives, a number of requirements have been derived that drive the design of CHEOPS. For the detection of Earth and super-Earth planets orbiting G5 dwarf stars with V-band magnitudes in the range 6 V 9 mag, a photometric precision of 20 ppm in 6 hours of integration time must be reached. This time corresponds to the transit duration of a planet with a revolution period of 50 days. In the case of Neptune-size planets orbiting K-type dwarf with magnitudes as faint as V=12 mag, a photometric precision of 85 ppm in 3 hours of integration time must be reached. The CHEOPS mission payload consists of only one instrument, a space telescope of 30 cm clear aperture, which has a single CCD focal plane detector. The total required duration of the CHEOPS mission is estimated to be 3.5 years (goal: 5 years).

Bibcode:

2014SPIE.9143E..5BB

Authors:

Bergomi, M.; Viotto, V.; Magrin, D.; Dima, M.; Greggio, D.; Farinato, J.; Marafatto, L.; Ragazzoni, R.; Munari, M.; Pagano, I.; Scandariato, G.; Scuderi, S.; Beck, T.; Buxton, R.; Piazza, D.; Benz, W.; Broeg, C.; Cessa, V.; Piotto, G.

Publication:

Proceedings of the SPIE, Volume 9143, id. 91435B 15 pp. (2014).

Copyright ©

(c) 2014: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2014 July

Abstract:

The CHaracterizing ExOPlanet Satellite (CHEOPS) is an ESA Small Mission whose launch is planned for the end of 2017. It is a Ritchey-Chretien telescope with a 320 mm aperture providing a FoV of 0.32 degrees, which will target nearby bright stars already known to host planets, and measure, through ultrahigh precision photometry, the radius of exo-planets, allowing to determine their composition. This paper will present the details of the AIV plan for a demonstration model of the CHEOPS Telescope with equivalent structure but different CTEs. Alignment procedures, needed GSEs and devised verification tests will be described and a path for the AIV of the flight model, which will take place at industries premises, will be sketched....

The CHaracterizing ExOPlanet Satellite (CHEOPS) is an ESA Small Mission whose launch is planned for the end of 2017. It is a Ritchey-Chretien telescope with a 320 mm aperture providing a FoV of 0.32 degrees, which will target nearby bright stars already known to host planets, and measure, through ultrahigh precision photometry, the radius of exo-planets, allowing to determine their composition. This paper will present the details of the AIV plan for a demonstration model of the CHEOPS Telescope with equivalent structure but different CTEs. Alignment procedures, needed GSEs and devised verification tests will be described and a path for the AIV of the flight model, which will take place at industries premises, will be sketched.

Bibcode:

2014SPIE.9143E..4LM

Authors:

Magrin, Demetrio; Farinato, Jacopo; Umbriaco, Gabriele; Kumar Radhakrishnan Santhakumari, Kalyan; Bergomi, Maria; Dima, Marco; Greggio, Davide; Marafatto, Luca; Ragazzoni, Roberto; Viotto, Valentina; Munari, Matteo; Pagano, Isabella; Scandariato, Gaetano; Scuderi, Salvatore; Piotto, Giampaolo; Beck, Thomas; Benz, Willy; Broeg, Christopher; Cessa, Virginie; Fortier, Andrea; Piazza, Daniele

Publication:

Proceedings of the SPIE, Volume 9143, id. 91434L 9 pp. (2014).

Copyright ©

(c) 2014: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2014 July

Abstract:

Spreading the PSF over a quite large amount of pixels is an increasingly used observing technique in order to reach extremely precise photometry, such as in the case of exoplanets searching and characterization via transits observations. A PSF top-hat profile helps to minimize the errors contribution due to the uncertainty on the knowledge of the detector flat field. This work has been carried out during the recent design study in the framework of the ESA small mission CHEOPS. Because of lack of perfect flat-fielding information, in the CHEOPS optics it is required to spread the light of a source into a well defined angular area, in a manner as uniform as possible. Furthermore this should be accomplished still retaining the features of a true focal plane onto the detector. In this way, for...

Spreading the PSF over a quite large amount of pixels is an increasingly used observing technique in order to reach extremely precise photometry, such as in the case of exoplanets searching and characterization via transits observations. A PSF top-hat profile helps to minimize the errors contribution due to the uncertainty on the knowledge of the detector flat field. This work has been carried out during the recent design study in the framework of the ESA small mission CHEOPS. Because of lack of perfect flat-fielding information, in the CHEOPS optics it is required to spread the light of a source into a well defined angular area, in a manner as uniform as possible. Furthermore this should be accomplished still retaining the features of a true focal plane onto the detector. In this way, for instance, the angular displacement on the focal plane is fully retained and in case of several stars in a field these look as separated as their distance is larger than the spreading size. An obvious way is to apply a defocus, while the presence of an intermediate pupil plane in the Back End Optics makes attractive to introduce here an optical device that is able to spread the light in a well defined manner, still retaining the direction of the chief ray hitting it. This can be accomplished through an holographic diffuser or through a lenslet array. Both techniques implement the concept of segmenting the pupil into several sub-zones where light is spread to a well defined angle. We present experimental results on how to deliver such PSF profile by mean of holographic diffuser and lenslet array. Both the devices are located in an intermediate pupil plane of a properly scaled laboratory setup mimicking the CHEOPS optical design configuration.

Bibcode:

2014SPIE.9143E..2JF

Authors:

Fortier, Andrea; Beck, Thomas; Benz, Willy; Broeg, Christopher; Cessa, Virginie; Ehrenreich, David; Thomas, Nicolas

Publication:

Proceedings of the SPIE, Volume 9143, id. 91432J 12 pp. (2014).

Copyright ©

(c) 2014: SPIE. Downloading of the abstract is permitted for personal use only.

Date

2014 July

Abstract:

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission (expected to launch in 2017) dedicated to search for exoplanet transits by means of ultra-high precision photometry. CHEOPS will provide accurate radii for planets down to Earth size. Targets will mainly come from radial velocity surveys. The CHEOPS instrument is an optical space telescope of 30 cm clear aperture with a single focal plane CCD detector. The tube assembly is passively cooled and thermally controlled to support high precision, low noise photometry. The telescope feeds a re-imaging optic, which supports the straylight suppression concept to achieve the required Signal to Noise....

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission (expected to launch in 2017) dedicated to search for exoplanet transits by means of ultra-high precision photometry. CHEOPS will provide accurate radii for planets down to Earth size. Targets will mainly come from radial velocity surveys. The CHEOPS instrument is an optical space telescope of 30 cm clear aperture with a single focal plane CCD detector. The tube assembly is passively cooled and thermally controlled to support high precision, low noise photometry. The telescope feeds a re-imaging optic, which supports the straylight suppression concept to achieve the required Signal to Noise.

Bibcode:

2014EPSC....9..376F

Authors:

Fortier, A.; Beck, T.; Benz, W.; Broeg, C.; Cessa, V.; Ehrenreich, D.; Pagano, I.; Peter, G.; Piazza, D.; Plesseria, J. -Y.; Ragazzoni, R.; Ratti, F.; Steller, M.; Szòke, J.; Thomas, N.

Publication:

European Planetary Science Congress 2014, EPSC Abstracts, Vol. 9, id. EPSC2014-376

Date

2014 March

Abstract:

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultrahigh precision photometry. It is expected to be launch ready at the end of 2017. CHEOPS will be the first space telescope dedicated to search for transits on bright stars already known to host planets. It will have access to more than 70% of the sky, allowing almost any interesting target to be observed. This will provide the unique capability of determining accurate radii for planets for which the mass has already been estimated from ground-based spectroscopic surveys and for new planets discovered by the next generation ground-based transits surveys (Neptunesize and smaller)....

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultrahigh precision photometry. It is expected to be launch ready at the end of 2017. CHEOPS will be the first space telescope dedicated to search for transits on bright stars already known to host planets. It will have access to more than 70% of the sky, allowing almost any interesting target to be observed. This will provide the unique capability of determining accurate radii for planets for which the mass has already been estimated from ground-based spectroscopic surveys and for new planets discovered by the next generation ground-based transits surveys (Neptunesize and smaller).

Bibcode:

2014CoSka..43..498B

Authors:

Broeg, C.; Benz, W.; Thomas, N.; Cheops Team

Publication:

Contributions of the Astronomical Observatory Skalnaté Pleso, vol. 43, no. 3, p. 498-498.

Date

2014 February

Abstract:

% Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground-based transit searches now reach milli-mag photometric precision and can discover Neptune size planets around bright stars. These searches will find exoplanets around bright stars anywhere on the sky, their discoveries representing prime science targets for further study due to the proximity and brightness of their host stars. A mission for transit follow-up measurements of these prime targets is currently lacking. The first ESA S-class mission CHEOPS (CHaracterizing ExoPlanet Satellite) will fill this gap. It will perform ultra-high precision photometric monitoring of selected bright target stars almost anywhere on the sky with sufficient precision to det...

% Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground-based transit searches now reach milli-mag photometric precision and can discover Neptune size planets around bright stars. These searches will find exoplanets around bright stars anywhere on the sky, their discoveries representing prime science targets for further study due to the proximity and brightness of their host stars. A mission for transit follow-up measurements of these prime targets is currently lacking. The first ESA S-class mission CHEOPS (CHaracterizing ExoPlanet Satellite) will fill this gap. It will perform ultra-high precision photometric monitoring of selected bright target stars almost anywhere on the sky with sufficient precision to detect Earth-sized transits. It will be able to detect transits of RV-planets by photometric monitoring if the geometric configuration results in a transit. For Hot Neptunes discovered from the ground, CHEOPS will be able to improve the transit light curve so that the radius can be determined precisely. Because of the host stars' brightness, high precision RV measurements will be possible for all targets. All planets observed in transit by CHEOPS will be validated and their masses will be known. This will provide valuable data for constraining the mass-radius relation of exoplanets, especially in the Neptune-mass regime. During the planned 3.5 year mission, about 500 targets will be observed. There will be 20% of open time available for the community to develop new science programmes.

Bibcode:

2013EPJWC..4703005B

Authors:

Broeg, C.; Fortier, A.; Ehrenreich, D.; Alibert, Y.; Baumjohann, W.; Benz, W.; Deleuil, M.; Gillon, M.; Ivanov, A.; Liseau, R.; Meyer, M.; Oloffson, G.; Pagano, I.; Piotto, G.; Pollacco, D.; Queloz, D.; Ragazzoni, R.; Renotte, E.; Steller, M.; Thomas, N.

Publication:

Hot Planets and Cool Stars, Garching, Germany, Edited by Roberto Saglia; EPJ Web of Conferences, Volume 47, id.03005

Date

2013 March

Abstract:

Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground based transit searches now reach milli-mag photometric precision and can discover Neptune size planets around bright stars. These searches will find exoplanets around bright stars anywhere on the sky, their discoveries representing prime science targets for further study due to the proximity and brightness of their host stars. A mission for transit follow-up measurements of these prime targets is currently lacking. The first ESA S-class mission CHEOPS (CHaracterizing ExoPlanet Satellite) will fill this gap. It will perform ultra-high precision photometric monitoring of selected bright target stars almost anywhere on the sky with sufficient precision to detec...

Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground based transit searches now reach milli-mag photometric precision and can discover Neptune size planets around bright stars. These searches will find exoplanets around bright stars anywhere on the sky, their discoveries representing prime science targets for further study due to the proximity and brightness of their host stars. A mission for transit follow-up measurements of these prime targets is currently lacking. The first ESA S-class mission CHEOPS (CHaracterizing ExoPlanet Satellite) will fill this gap. It will perform ultra-high precision photometric monitoring of selected bright target stars almost anywhere on the sky with sufficient precision to detect Earth sized transits. It will be able to detect transits of RV-planets by photometric monitoring if the geometric configuration results in a transit. For Hot Neptunes discovered from the ground, CHEOPS will be able to improve the transit light curve so that the radius can be determined precisely. Because of the host stars' brightness, high precision RV measurements will be possible for all targets. All planets observed in transit by CHEOPS will be validated and their masses will be known. This will provide valuable data for constraining the mass-radius relation of exoplanets, especially in the Neptune-mass regime. During the planned 3.5 year mission, about 500 targets will be observed. There will be 20% of open time available for the community to develop new science programmes.

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