AO-1: Approved Programmes

Announced on 24 July 2019

The first Announcement of Opportunity (AO-1) for the CHEOPS Guest Observers Programme came out on 19 March 2019, and closed approximately 8 weeks later on 16 May 2019. The CHEOPS Time Allocation Committee (TAC) met on the 2-3 July 2019.

Based on the recommendations made by the TAC, the Director of Science has awarded observing time on CHEOPS to the proposals listed in the table below. 12 programmes have been awarded observing time on CHEOPS, covering a total of 530 orbits. The number of orbits that have been awarded is below what had been foreseen to be allocated for this call - details of how it will be possible to apply for the remaining orbits will be announced in coming months.

Targets that are part of these programmes have been added to the Reserved Target List and cannot be included in observing programmes of other scientists until the AO-1 observations have been completed.

Principal Investigators of proposals that have been awarded time will be contacted by email, and are required to complete and submit observation requests at their earliest convenience  Guidelines on how to prepare observation requests can be found in the document at this link.

Abstracts

ID001 — Teasing a star with a planet: a CHEOPS study of HD 17156 and its hot Jupiter (PI: Ignazio Pillitteri)
The large number of close-in Jupiter-size exoplanets prompts the question whether star-planet interaction (SPI) effects can be detected. We focus our attention on the system HD 17156, having a Jupiter-mass planet in a very eccentric orbit. A brightening of the stellar corona in X-rays was observed during a periastron passage of its planet and this could be a systematic effect of magnetic SPI. With this proposal we aim at the detection of any increase of the flux in the CHEOPS band when the planet is close to periastron. We also aim at investigating the origin of the flaring activity, whether it is due to the interaction of the stellar and planetary magnetic fields, or originating from accretion of material tidally stripped by the planet and falling onto the stellar surface.

ID002 — Three resonant planets: Tracking the nearby multi-planet system GJ 9827 (PI: Seth Redfield)
We propose primary transit observations of three Super−Earth planets in the planetary system around a bright, nearby star, GJ 9827. We announced the detection of three super−Earth planets in 1:3:5 commensurability, the inner planet, GJ 9827 b having a period of 1.2 days. This is the nearest planetary system that Kepler or K2 has found, at 30 pc, and given its brightness is one of the top systems for follow−up characterization. There are several opportunities in the CHEOPS visibility windows to obtain all three transits in a short period of time, or separately. The proximity to 1:3:5 resonance is intriguing from a dynamical standpoint. The observations will provide a firm determination of the ephemerides in order to explore any transit timing variations and support follow−up observations from space and ground−based telescopes. Subsequent follow-up has indicated that there is a transit timing variation that may have been undetected during the K2 campaign, but should be easily detectable now. Due to the brightness of the host star, this planetary system is likely to be extensively observed in the years to come. Indeed, our team has acquired observations of the planets orbiting GJ9827 with Hubble in the ultraviolet. The proposed observations will provide an important foundation to planning and designing these and future observations, in particular atmospheric characterization with JWST.

ID004 — Kelt-22A b: An ideal candidate for the first definitive detection of orbital tidal dissipation and determination of the second degree fluid Love number (PI: Andrew Ridden-Harper)
Theory suggests that the orbits of some hot Jupiters are decaying due to tidal interactions with their host stars. The hot Jupiter KELT-22A b is predicted to have a rapidly decaying orbit, causing its orbital period to decrease by 1.9 secs per year (Labadie-Bartz et al. 2019). Here were propose to verify the theory used to make this prediction by directly measuring the orbital decay to unprecedented precision. In fact, our precision will allow us to significantly detect changes in its orbital period up to two orders of magnitude smaller than the predicted value, allowing us to place strong limits on the modified tidal dissipative parameter Q’* = Q*/k2 (where Q* is the tidal dissipative parameter and k2 is the second degree fluid Love number) even in the event of a non-detection. Furthermore, Hellard et al. (2019) recently showed that with a precision achievable by CHEOPS, it is possible to detect the deviations in the transit light curve caused by a tidally distorted non-spherical hot Jupiter, and directly constrain k2. This value is directly proportional to the concentration of mass towards the planet’s center so constraining k2 will provide unprecedented insight into the planet’s internal structure. A precise measurement of Q’* and the planet’s k2 number will provide a direct constraint on the tidal quality factor, Q*, of its host star. Overall, these observations will break new ground in our understanding of tidal dissipation and the internal structures of hot Jupiters.

ID005 — Measuring the orbital obliquity of the warm Jupiter K2-139b (PI: Alexis Smith)
We will use CHEOPS to measure four transits of the warm Jupiter K2-139b across the face of its host star, K2-139. K2-139 is an active K0V star, and has previously been observed to exhibit significant star spots. By measuring anomalies in the light curves caused by the planet crossing stellar spots during transit, we will measure the spin-orbit angle (obliquity), that is the angle between the stellar spin axis, and the planetary orbital axis, for the K2-139 system. Spin-orbit angles offer a crucial piece of observational evidence, vital for understanding planetary migration and evolution.

ID006 — Rapidly rotating stars and their transiting planets: a unique laboratory of many astrophysical effects (PI: Zoltan Garai)
We propose a mini-survey of rapidly rotating early-type main-sequence stars with transiting planets, similar to the Kepler-13 system, to constrain their planetary and stellar parameters, and to characterize the star-planet interactions in these cases. For this mini-survey we have selected the KELT-17, KELT-19A and KELT-21 planetary systems. Some astrophysical effects in such systems are not well understood yet, since there are no sufficiently precise photometric observations. Based on the precise CHEOPS transit light curves of the systems, we aim to search for similar asymmetries, as it was detected in the Kepler-13 system, and to study some astrophysical effects simultaneously.

ID007 — Planetary material orbiting white dwarfs (PI: Brett Morris)
White dwarfs are the final evolutionary phase of 95% of stars, and therefore the fated host stars of many exoplanets. White dwarf spectroscopy shows that nearly half of white dwarfs contain metals in their atmospheres, which must have been accreted from metal-rich planetary material that survived the red giant phase of stellar evolution. We can use metal pollution in white dwarf atmospheres as sirens, alerting us to recent accretion, in order to prioritize an efficient sample of white dwarfs to search for transiting planetary debris. We propose to observe seven of the nearest, brightest, metal-polluted white dwarfs with CHEOPS for periodic photometric variations due to orbiting material.

ID013 — Exploring the diversity of small planet compositions (PI: Diana Dragomir)
The sizes and masses of planets provide a powerful constraint on their composition. But until last year, the exoplanet community had access to large samples of just radii for small planets. TESS is enabling us to finally also measure the masses of an ensemble of small planets. Complementarily, we propose to use CHEOPS to measure precise radii for five small TESS planets in order to constrain their interior composition, and explore the recently discovered radius valley. The proposed observations will also serve to significantly refine the ephemerides of these planets, constrain their orbital eccentricity, and provide an anchor point at visible wavelengths for infrared transmission spectroscopy observations.

ID015 — Is the Neptune-mass planet around the bright HD67228 transiting? (PI: Isabelle Boisse)
HD67228 is a very bright star in the Northern sky with a V magnitude of 5.3. Thanks to SOPHIE measurements, we discovered a Neptune-mass planet around this star on a 10.1 days orbit. With a 9.1% of transit probability, we ask for CHEOPS to search for the transit of the planet since its host star is not plan to be observed by TESS. We ask for one visit of 46.7 h = 28 orbits in order to cover the uncertainty on the transit epoch. With a Neptune density, we expect a planetary radius of 3.85 Earth-radius, leading to a transit of 3.5 hours with 360 ppm. Whereas the error budget for this bright star with CHEOPS is of less than 18 ppm, the transit should be easily detectable within one visit (even taking into account the 45% interruption). If detected, it will be the brightest system with a small-mass planet with mass and radius accurately measured.

ID017 — Measuring timing transit variations in the dynamically remarkable system K2-138 (PI: Theo Lopez)
Compact multiple systems of small transiting exoplanets show remarkable dynamics bringing new insights to the formation and evolution of exoplanets. Such a system was identified around K2-138 in the K2 C12 data. It harbours 6 planets in a chain of near 3:2 mean motion resonance. This is an ideal target to search for timing transit variations, allowing to further constrain the masses of the outer planets. Moreover, in addition to 215 HARPS radial velocities we already have, it would make K2-138 one of the very few systems with both RVs and TTVs, allowing to calibrate the two mass measurement techniques and understand multi-planet formation and dynamics.

ID019 — The first young Jupiter transit with CHEOPS (PI: Todorov/Desert)
We propose to observe a transit of recently discovered young warm Jupiter V1298 Tau b (Rp ~ 0.9 RJup). By measuring the transit duration, we will constrain its eccentricity, allowing us to test formation and migration scenarios at a very early system age (~23Myr) - high eccentricity would point to migration via planet-planet scattering, while low eccentricity would be indicative of slower orbital evolution or in situ formation. We will also constrain the bulk properties of its atmosphere, by estimating its scale height. Our observation will enable future detailed atmospheric studies via transit and secondary eclipse spectroscopy with HST, JWST, and ARIEL, as well as ground-based instruments. This is an opportunity for CHEOPS to lay the foundations of the characterization of transiting young warm gas giant planets as a new class, and contribute to our understanding of gas giant planet formation and evolution.

ID020 — Characterisation of the very young planet DS Tuc b with CHEOPS (PI: Silvano Desidera)
The planet DS Tuc b, proposed as candidate planet by the TESS team (TOI-200) and recently validated by our group (Benatti et al. 2019), is the only known transiting planet younger than 100 Myr orbiting a star brighter than V 10. With an age of just 40 Myr and a radius of 5.6 Rearth, it is expected to be highly inflated due to the still ongoing gravitational contraction and to have a mass of about 5-10 Mearth from available theoretical models. These characteristics will make it a benchmark for the study of the evolution of planetary structure and of evaporation of planetary atmospheres and for the understanding of the timescales of migration mechanisms of close-in planets. Unfortunately, interpreting TESS data is not straightforward due to an overlap of stellar activity, instrumental systematics and limited observing baseline. We propose to observe with CHEOPS five transits of DS Tuc b, aiming at a significant refinement of its orbital ephemeris and improving its planetary parameters, above all its radius. This will be helpful not only in better constraining our formation and evolutionary models, but also to plan a more effective multi-instrument follow-up, which will include mass measurement through radial velocities and atmospheric characterization through transmission spectroscopy.

ID021 — Hunting for exocomets transiting the young naked-eye star 5 Vulpeculae (PI: Isabel Rebollido)
Since the first detection of exocomets (or Falling Evaporating Bodies) by Ferlet et al. in 1987 around the A6V star β Pictoris, only around other 20 stars have been observed to host similar activity in their high-resolution optical spectra. Recent discoveries of exocomet-like signatures in photometric data taken by the Kepler mission and in the first results by TESS, have introduced a new detection and analysis technique to the exocometary field. While all sky surveys, as TESS, represent promising opportunities as discovery experiments, one of the most remarkable exocomet-host stars, 5 Vulpeculae, will neither be observed by the mission, nor has it archival data in the Kepler archive due to its location in the sky. CHEOPS represents the only opportunity to obtain a short-cadence high-precision light curve that could help reveal small bodies in the system. We propose a 27 orbit observing campaign in order to optimize the possibility of detection.

This page was last updated on 24 July 2019.