J/A+A/666/A47 MASCARA-4 b light and RV curves (Zhang+, 2022)
Transmission spectroscopy of the ultra-hot Jupiter MASCARA-4 b.
Disentangling the hydrostatic and exospheric regimes of ultra-hot Jupiters.
Zhang Y., Snellen I.A.G., Wyttenbach A., Nielsen L.D., Lendl M.,
Casasayas-Barris N., Chaverot G., Kesseli A.Y., Lovis C., Pepe F.A.,
Psaridi A., Seidel J.V., Udry S., Ulmer-Moll S.
<Astron. Astrophys. 666, A47 (2022)>
=2022A&A...666A..47Z 2022A&A...666A..47Z (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ; Optical ;
Radial velocities
Keywords: planets and satellites: atmospheres - techniques: spectroscopic
Abstract:
Ultra-hot Jupiters (UHJs), rendering the hottest planetary
atmospheres, offer great opportunities of detailed characterisation
with high-resolution spectroscopy. The extremely irradiated
atmospheres are interesting laboratories for studying the mass loss
through hydrodynamic escapes. MASCARA-4 b is a recently discovered
close-in gas giant belonging to this category.
We aim to characterise the UHJ MASCARA-4 b in detail, in particular
searching for chemical species in its atmosphere and put these in the
context of the growing knowledge on the atmospheric properties of
UHJs.
In order to refine the planet mass, we took high-resolution spectra of
MASCARA-4 with the CORALIE spectrograph at the Swiss 1.2m Euler
telescope, and extracted radial velocity measurements. We observed two
transits of MASCARA-4 b with the high-resolution spectrograph ESPRESSO
at ESO's Very Large Telescope. Simultaneous photometry was carried out
with EulerCam installed at the Euler telescope to deliver updated
system and planet parameters. We searched for atomic, ionic, and
molecular species via individual absorption lines and
cross-correlation techniques. These results are compared to literature
studies on UHJs characterised to date.
With CORALIE and EulerCam observations, we updated the mass of
MASCARA-4 b (1.675±0.241 Jupiter masses) as well as other system and
planet parameters. In the transmission spectrum derived from ESPRESSO
observations, we resolve excess absorption by Hα, Hβ, NaI
D1&D2, CaII H&K, and a few strong individual lines of MgI, FeI and
FeII. We also present the cross-correlation detection of MgI, CaI,
CrI, FeI and FeII. The absorption strength of FeIi significantly
exceeds the prediction from a hydrostatic atmospheric model, which is
also commonly observed in other UHJs. We attribute this to the
presence of FeII in the exosphere as a consequence of hydrodynamic
outflows. This is further supported by the positive correlation of
absorption strengths of FeII with the Hα line, which is expected
to probe the extended upper atmospheres and the mass loss process.
Comparing transmission signatures of various species in the UHJ
population allows us to disentangle the hydrostatic regime (as traced
via the absorption by MgI and FeI) from the exospheres (as probed by
Hα and FeII) of the strongly irradiated atmospheres.
Description:
We present photometric time-series obtained with EulerCam installed at
the Swiss 1.2m Euler telescope. We also present radial-velocity
measurements of MASCARA-4 obtained with CORALIE spectrograph at the
Euler telescope.
Objects:
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RA (2000) DE Designation(s)
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09 50 19.20 -66 06 49.9 MASCARA-4 = HD 85628
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
phot.dat 32 1008 MASCARA-4 transit photometry with EulerCam
rv.dat 34 20 MASCARA-4 radial velocities measured with CORALIE
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Byte-by-byte Description of file: phot.dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 d BJD Barycentric Julian Date in the Barycentric
Dynamical Time (BJD-2450000)
14- 21 F8.6 --- Flux Normalized Flux
25- 32 F8.6 --- e_Flux Normalized Flux error
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Byte-by-byte Description of file: rv.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d BJD Barycentric Julian Date ((BJD-2400000)
16- 24 F9.6 km/s RV Barycentric Radial Velocity
28- 34 F7.5 km/s e_RV Radial Velocity error
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Acknowledgements:
Yapeng Zhang, yzhang(at)strw.leidenuniv.nl
(End) Patricia Vannier [CDS] 18-Aug-2022