- ID:
- ivo://CDS.VizieR/J/AJ/160/230
- Title:
- WASP-31b and host star radius compared with IMACS
- Short Name:
- J/AJ/160/230
- Date:
- 10 Dec 2021
- Publisher:
- CDS
- Description:
- We present a new optical (400-950nm) transmission spectrum of the hot Jupiter WASP-31b (M=0.48M_Jup_; R=1.54R_Jup_; P=3.41days), obtained by combining four transit observations. These transits were observed with IMACS on the Magellan Baade Telescope at Las Campanas Observatory as part of the ACCESS project. We investigate the presence of clouds/hazes in the upper atmosphere of this planet, as well as the contribution of stellar activity on the observed features. In addition, we search for absorption features of the alkali elements NaI and KI, with particular focus on KI, for which there have been two previously published disagreeing results. Observations with Hubble Space Telescope (HST)/STIS detected KI, whereas ground-based low- and high- resolution observations did not. We use equilibrium and nonequilibrium chemistry retrievals to explore the planetary and stellar parameter space of the system with our optical data combined with existing near-IR observations. Our best-fit model is that with a scattering slope consistent with a Rayleigh slope ({alpha}=5.3_-3.1_^+2.9^), high-altitude clouds at a log cloud top pressure of -3.6_-2.1_^+2.7^bars, and possible muted H2O features. We find that our observations support other ground-based claims of no KI. Clouds are likely why signals like H2O are extremely muted and Na or K cannot be detected. We then juxtapose our Magellan/IMACS transmission spectrum with existing VLT/FORS2, HST/WFC3, HST/STIS, and Spitzer observations to further constrain the optical-to-infrared atmospheric features of the planet. We find that a steeper scattering slope ({alpha}=8.3{+/-}1.5) is anchored by STIS wavelengths blueward of 400nm and only the original STIS observations show significant potassium signal.
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- ID:
- ivo://CDS.VizieR/J/A+A/630/A89
- Title:
- WASP-12b and WASP-43b griz light curves
- Short Name:
- J/A+A/630/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The TESS and PLATO missions are expected to find vast numbers of new transiting planet candidates. However, only a fraction of these candidates will be legitimate planets, and the candidate validation will require a significant amount of follow-up resources. Radial velocity (RV) follow-up study can be carried out only for the most promising candidates around bright, slowly rotating, stars. Thus, before devoting RV resources to candidates, they need to be vetted using cheaper methods, and, in the cases for which an RV confirmation is not feasible, the candidate's true nature needs to be determined based on these alternative methods alone. We study the applicability of multicolour transit photometry in the validation of transiting planet candidates when the candidate signal arises from a real astrophysical source (transiting planet, eclipsing binary, etc.), and not from an instrumental artefact. Particularly, we aim to answer how securely we can estimate the true uncontaminated star-planet radius ratio when the light curve may contain contamination from unresolved light sources inside the photometry aperture when combining multicolour transit observations with a physics-based contamination model in a Bayesian parameter estimation setting. More generally, we study how the contamination level, colour differences between the planet host and contaminant stars, transit signal-to-noise ratio, and available prior information affect the contamination and true radius ratio estimates. The study is based on simulations and ground-based multicolour transit observations. The contamination analyses were carried out with a contamination model integrated into the PYTRANSIT V2 transit modelling package, and the observations were carried out with the MuSCAT2 multicolour imager installed in the 1.5m Telescopio Carlos Sanchez in the Teide Observatory, in Tenerife. We show that multicolour transit photometry can be used to estimate the amount of flux contamination and the true radius ratio. Combining the true radius ratio with an estimate for the stellar radius yields the true absolute radius of the transiting object, which is a valuable quantity in statistical candidate validation, and enough in itself to validate a candidate whose radius falls below the theoretical lower limit for a brown dwarf.
- ID:
- ivo://CDS.VizieR/J/MNRAS/482/301
- Title:
- WASP-147b, 160Bb, 164b, and 165b phot. and RV
- Short Name:
- J/MNRAS/482/301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four transiting hot Jupiters, WASP-147, WASP-160B, WASP-164, and WASP-165 from the WASP survey. WASP-147b is a near Saturn-mass (Mp=0.28M_J_) object with a radius of 1.11R_J_ orbiting a G4 star with a period (of 4.6d. WASP-160Bb has a mass and radius (Mp=0.28M_J_, Rp=1.09R_J_) (near-identical to WASP-147b, but is less irradiated, orbiting a metal-rich ([Fe/H]*=0.27) K0 star with a period of 3.8d. WASP-160B is part of a near equal-mass visual binary with an on-sky separation of 28.5 arcsec. WASP-164b is a more massive (Mp=2.13M_J_, Rp=1.13R_J_) hot Jupiter, orbiting a G2 star on a close-in (P=1.8d), but tidally stable orbit. WASP-165b is a classical (Mp=0.66M_J_, Rp=1.26R_J_) hot Jupiter in a 3.5d period orbit around a metal-rich ([Fe/H]*=0.33) star. WASP-147b and WASP-160Bb are promising targets for atmospheric characterization through transmission spectroscopy, while WASP-164b presents a good target for emission spectroscopy.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A136
- Title:
- WASP-18b HST/WFC3 spectroscopic phase curves
- Short Name:
- J/A+A/625/A136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of a full-orbit, spectroscopic phase curve of the ultra hot Jupiter (UHJ) WASP-18b, obtained with the Wide Field Camera 3 aboard the Hubble Space Telescope. We measured the normalised day-night contrast of the planet as >0.96 in luminosity: the disc-integrated dayside emission from the planet is at 964+/-25ppm, corresponding to 2894+/-30K, and we place an upper limit on the nightside emission of <32ppm or 1430K at the 3{sigma}level. We also find that the peak of the phase curve exhibits a small, but significant oset in brightness of 4.5+/-0.5 degrees eastward. We compare the extracted phase curve and phase-resolved spectra to 3D global circulation models and find that broadly the data can be well reproduced by some of these models. We find from this comparison several constraints on the atmospheric properties of the planet. Firstly we find that we need ecient drag to explain the very inefficient day-night recirculation observed.We demonstrate that this drag could be due to Lorentz-force drag by a magnetic field as weak as 10 gauss. Secondly, we show that a high metallicity is not required to match the large day-night temperature contrast. In fact, the effect of metallicity on the phase curve is different from cooler gas-giant counterparts because of the high-temperature chemistry in the atmosphere of WASP-18b. Additionally, we compared the current UHJ spectroscopic phase curves, WASP-18b and WASP-103b, and show that these two planets provide a consistent picture with remarkable similarities in their measured and inferred properties. However, key differences in these properties, such as their brightness osets and radius anomalies, suggest that UHJ could be used to separate between competing theories for the inflation of gas-giant planets.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A86
- Title:
- WASP-48b Ks-band occultation lightcurves
- Short Name:
- J/A+A/615/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a detection of thermal emission from the hot Jupiter WASP-48b in the Ks-band. We used the Wide-field Infra-red Camera on the 3.6-m Canada-France Hawaii Telescope to observe an occultation of the planet by its host star. From the resulting occultation lightcurve we find a planet-to-star contrast ratio in the Ks-band of 0.136+/-0.014% , in agreement with the value of 0.109+/-0.027% previously determined. We fit the two Ks-band occultation lightcurves simultaneously with occultation lightcurves in the H-band and the Spitzer 3.6-um and 4.5-um bandpasses, radial velocity data, and transit lightcurves. From this, we revise the system parameters and construct the spectral energy distribution (SED) of the dayside atmosphere. By comparing the SED with atmospheric models, we find that both models with and without a thermal inversion are consistent with the data. We find the planet's orbit to be consistent with circular (e<0.072 at 3 sigma).
- ID:
- ivo://CDS.VizieR/J/MNRAS/497/5182
- Title:
- WASP-21b light curves
- Short Name:
- J/MNRAS/497/5182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the optical transmission spectrum of the highly inflated Saturn- mass exoplanet WASP-21b, using three transits obtained with the ACAM instrument on the William Herschel Telescope through the LRG-BEASTS survey (Low Resolution Ground-Based Exoplanet Atmosphere Survey using Transmission Spectroscopy). Our transmission spectrum covers a wavelength range of 4635-9000{AA}, achieving an average transit depth precision of 197ppm compared to one atmospheric scale height at 246ppm. We detect NaI absorption in a bin width of 30{AA}, at >4{sigma} confidence, which extends over 100{AA}. We see no evidence of absorption from KI. Atmospheric retrieval analysis of the scattering slope indicates it is too steep for Rayleigh scattering from H_2, but is very similar to that of HD 189733b. The features observed in our transmission spectrum cannot be caused by stellar activity alone, with photometric monitoring of WASP-21 showing it to be an inactive star. We therefore conclude that aerosols in the atmosphere of WASP-21b are giving rise to the steep slope that we observe, and that WASP-21b is an excellent target for infra-red observations to constrain its atmospheric metallicity.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A36
- Title:
- WASP-121b optical phase curve
- Short Name:
- J/A+A/637/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of TESS optical photometry of WASP-121b, which reveals the phase curve of this transiting ultra-hot Jupiter. Its hotspot is located at the sub-stellar point, showing inefficient heat transport from the dayside (2870+/-50K) to the nightside (<2500K at 3{sigma}) at the altitudes probed by TESS. The TESS eclipse depth, measured at the shortest wavelength to date for WASP-121b, confirms the strong deviation from blackbody planetary emission. Our atmospheric retrieval on the complete emission spectrum supports the presence of a temperature inversion, which can be explained by the presence of VO and possibly TiO and FeH. The strong planetary emission at short wavelengths could arise from an H^-^ continuum.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A80
- Title:
- WASP-121b secondary eclipse in 2MASS K band
- Short Name:
- J/A+A/625/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ground-based observations of the secondary eclipse in the 2MASS K band are presented for the hot Jupiter WASP-121b. These are the first occultation observations of an extrasolar planet that were carried out with an instrument attached to a 1m class telescope (the SMARTS 1.3m). We find a highly significant eclipse depth of (0.228+/-0.023)%. Together with other planet atmosphere measurements, including the Hubble Space Telescope near-infrared emission spectrum, current data support more involved atmosphere models with species producing emission and absorption features, rather than simple smooth blackbody emission. Analysis of the time difference between the primary and secondary eclipses and the durations of these events yields an eccentricity of e=0.0207+/-0.0153, which is consistent with the earlier estimates of low or zero eccentricity, but with a smaller error. Comparing the observed occultation depth in the K band with the one derived under the assumption of zero Bond albedo and full heat redistribution, we find that WASP-121b has a deeper observed occultation depth than predicted. Together with the sample of 31 systems with K-band occultation data, this observation lends further support to the idea of inefficient heat transport between the day and night sides for most of the hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A57
- Title:
- WASP-121 b Swift UVOT near-UV transit observations
- Short Name:
- J/A+A/623/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Close-in gas planets are subject to continuous photoevaporation that can erode their volatile envelopes. Today, ongoing mass loss has been confirmed in a few individual systems via transit observations in the ultraviolet spectral range. We demonstrate that the Ultraviolet/Optical Telescope (UVOT) onboard the Neil Gehrels Swift Observatory enables photometry to a relative accuracy of about 0.5% and present the first near-UV (200-270nm, NUV) transit observations of WASP-121 b, a hot Jupiter with one of the highest predicted mass-loss rates. The data cover the orbital phases 0.85 to 1.15 with three visits. We measure a broad-band NUV transit depth of 2.10+/-0.29%. While still consistent with the optical value of 1.55%, the NUV data indicate excess absorption of 0.55% at a 1.9-sigma level. Such excess absorption is known from the WASP-12 system, and both of these hot Jupiters are expected to undergo mass loss at extremely high rates. With a CLOUDY simulation, we show that absorption lines of Fe II in a dense extended atmosphere can cause broad-band NUV absorption at the 0.5% level. Given the numerous lines of low-ionization metals, the NUV range is a promising tracer of photoevaporation in the hottest gas planets.
- ID:
- ivo://CDS.VizieR/J/AJ/157/43
- Title:
- WASP-161b, WASP-163b and WASP-170b
- Short Name:
- J/AJ/157/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery by the WASP-South transit survey of three new transiting hot Jupiters, WASP-161 b, WASP-163 b and WASP-170 b. Follow-up radial velocities obtained with the Euler/CORALIE spectrograph and high-precision transit light curves obtained with the TRAPPIST-North, TRAPPIST-South, SPECULOOS-South, NITES, and Euler telescopes have enabled us to determine the masses and radii for these transiting exoplanets. WASP-161 b completes an orbit around its V=11.1 F6V-type host star in 5.406 days, and has a mass and radius of 2.5+/-0.2M_Jup_ and 1.14+/-0.06R_Jup_ respectively. WASP-163 b has an orbital period of 1.609-days, a mass of 1.9+/-0.2M_Jup_, and a radius of 1.2+/-0.1R_Jup_. Its host star is a V=12.5 G8-type dwarf. WASP-170 b is on a 2.344-days orbit around a G1V-type star of magnitude V=12.8. It has a mass of 1.7+/-0.2M_Jup_ and a radius of 1.14+/-0.09R_Jup_. Given their irradiations (~10^9^erg/s/cm^2^) and masses, the three new planets' sizes are in good agreement with classical structure models of irradiated giant planets.
