The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS
(2020) In Astronomy and Astrophysics 643.- Abstract
- The CHEOPS space mission dedicated to exoplanet follow-up was launched in December 2019, equipped with the capacity to perform photometric measurements at the 20 ppm level. As CHEOPS carries out its observations in a broad optical passband, it can provide insights into the reflected light from exoplanets and constrain the short-wavelength thermal emission for the hottest of planets by observing occultations and phase curves. Here, we report the first CHEOPS observation of an occultation, namely, that of the hot Jupiter WASP-189 b, a MP ≈ 2MJ planet orbiting an A-type star. We detected the occultation of WASP-189 b at high significance in individual measurements and derived an occultation depth of dF = 87.9 ± 4.3 ppm based on four... (More)
- The CHEOPS space mission dedicated to exoplanet follow-up was launched in December 2019, equipped with the capacity to perform photometric measurements at the 20 ppm level. As CHEOPS carries out its observations in a broad optical passband, it can provide insights into the reflected light from exoplanets and constrain the short-wavelength thermal emission for the hottest of planets by observing occultations and phase curves. Here, we report the first CHEOPS observation of an occultation, namely, that of the hot Jupiter WASP-189 b, a MP ≈ 2MJ planet orbiting an A-type star. We detected the occultation of WASP-189 b at high significance in individual measurements and derived an occultation depth of dF = 87.9 ± 4.3 ppm based on four occultations. We compared these measurements to model predictions and we find that they are consistent with an unreflective atmosphere heated to a temperature of 3435 ± 27 K, when assuming inefficient heat redistribution. Furthermore, we present two transits of WASP-189 b observed by CHEOPS. These transits have an asymmetric shape that we attribute to gravity darkening of the host star caused by its high rotation rate. We used these measurements to refine the planetary parameters, finding a ~25% deeper transit compared to the discovery paper and updating the radius of WASP-189 b to 1.619 ± 0.021RJ. We further measured the projected orbital obliquity to be λ = 86.4-4.4+2.9°, a value that is in good agreement with a previous measurement from spectroscopic observations, and derived a true obliquity of ψ = 85.4 ± 4.3°. Finally, we provide reference values for the photometric precision attained by the CHEOPS satellite: for the V = 6.6 mag star, and using a 1-h binning, we obtain a residual RMS between 10 and 17 ppm on the individual light curves, and 5.7 ppm when combining the four visits. © ESO 2020. (Less)
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- author
- Lendl, M. ; Davies, Melvyn B LU and Wolter, D.
- author collaboration
- organization
- publishing date
- 2020
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Planets and satellites: atmospheres, Planets and satellites: individual: WASP-189 b, Techniques: photometric, Extrasolar planets, Interplanetary flight, Photometry, Stars, Gravity darkening, Model prediction, Photometric measurements, Photometric precision, Reference values, Reflected light, Short wavelengths, Thermal emissions, Orbits
- in
- Astronomy and Astrophysics
- volume
- 643
- article number
- 202038677
- publisher
- EDP Sciences
- external identifiers
-
- scopus:85096034316
- ISSN
- 1432-0746
- DOI
- 10.1051/0004-6361/202038677
- language
- English
- LU publication?
- yes
- id
- 225e71fd-aea4-4d1a-8774-592b7c08980e
- date added to LUP
- 2020-11-27 15:51:58
- date last changed
- 2023-01-01 01:59:11
@article{225e71fd-aea4-4d1a-8774-592b7c08980e,
abstract = {{The CHEOPS space mission dedicated to exoplanet follow-up was launched in December 2019, equipped with the capacity to perform photometric measurements at the 20 ppm level. As CHEOPS carries out its observations in a broad optical passband, it can provide insights into the reflected light from exoplanets and constrain the short-wavelength thermal emission for the hottest of planets by observing occultations and phase curves. Here, we report the first CHEOPS observation of an occultation, namely, that of the hot Jupiter WASP-189 b, a MP ≈ 2MJ planet orbiting an A-type star. We detected the occultation of WASP-189 b at high significance in individual measurements and derived an occultation depth of dF = 87.9 ± 4.3 ppm based on four occultations. We compared these measurements to model predictions and we find that they are consistent with an unreflective atmosphere heated to a temperature of 3435 ± 27 K, when assuming inefficient heat redistribution. Furthermore, we present two transits of WASP-189 b observed by CHEOPS. These transits have an asymmetric shape that we attribute to gravity darkening of the host star caused by its high rotation rate. We used these measurements to refine the planetary parameters, finding a ~25% deeper transit compared to the discovery paper and updating the radius of WASP-189 b to 1.619 ± 0.021RJ. We further measured the projected orbital obliquity to be λ = 86.4-4.4+2.9°, a value that is in good agreement with a previous measurement from spectroscopic observations, and derived a true obliquity of ψ = 85.4 ± 4.3°. Finally, we provide reference values for the photometric precision attained by the CHEOPS satellite: for the V = 6.6 mag star, and using a 1-h binning, we obtain a residual RMS between 10 and 17 ppm on the individual light curves, and 5.7 ppm when combining the four visits. © ESO 2020.}},
author = {{Lendl, M. and Davies, Melvyn B and Wolter, D.}},
issn = {{1432-0746}},
keywords = {{Planets and satellites: atmospheres; Planets and satellites: individual: WASP-189 b; Techniques: photometric; Extrasolar planets; Interplanetary flight; Photometry; Stars; Gravity darkening; Model prediction; Photometric measurements; Photometric precision; Reference values; Reflected light; Short wavelengths; Thermal emissions; Orbits}},
language = {{eng}},
publisher = {{EDP Sciences}},
series = {{Astronomy and Astrophysics}},
title = {{The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS}},
url = {{http://dx.doi.org/10.1051/0004-6361/202038677}},
doi = {{10.1051/0004-6361/202038677}},
volume = {{643}},
year = {{2020}},
}