J/A+A/628/A9 MASCARA-2b transmission spectra (Casasayas-Barris+, 2019)
Atmospheric characterisation of the ultra-hot Jupiter MASCARA-2b/KELT-20b.
Detection of CaII, FeII, NaI, and the Balmer series of H (Hα, Hβ, and
Hγ) with high-dispersion transit spectroscopy.
Casasayas-Barris N., Palle E., Yan F., Chen G., Kohl S., Stangret M.
Parviainen H., Helling Ch., Watanabe N., Czesla S., Montanes-Rodriguez P.,
Nagel E., Narita N., Nortmann L., Nowak G., Schmitt J.H.M.M.,
Zapatero Osorio M.R.
<Astron. Astrophys. 628, A9 (2019)>
=2019A&A...628A...9C 2019A&A...628A...9C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Spectroscopy
Keywords: planets and satellites: atmospheres - planetary systems -
methods: observational - techniques: spectroscopic -
planets and satellites: individual: MASCARA-2b -
planets and satellites: individual: KELT-20b
Abstract:
Ultra-hot Jupiters orbit very close to their host star and
consequently receive strong irradiation, causing their atmospheric
chemistry to be different from the common gas giants. Here, we have
studied the atmosphere of one of these particular hot planets,
MASCARA- 2b/KELT-20b, using four transit observations with high
resolution spectroscopy facilities. Three of these observations were
performed with HARPS-N and one with CARMENES. Additionally, we
simultaneously observed one of the transits with MuSCAT2 to monitor
possible spots in the stellar surface. At high resolution, the
transmission residuals show the effects of Rossiter-McLaughlin and
centre- to-limb variations from the stellar lines profiles, which we
have corrected to finally extract the transmission spectra of the
planet. We clearly observe the absorption features of CaII, FeII, NaI,
Hα, and Hβ in the atmosphere of MASCARA-2b, and indications
of Hγ and MgI at low signal-to-noise ratio. In the case of NaI,
the true absorption is difficult to disentangle from the strong
telluric and interstellar contamination. The results obtained with
CARMENES and HARPS-N are consistent, measuring an Hα absorption
depth of 0.68±0.05 and 0.59±0.07%, and NaI absorption of
0.11±0.04 and 0.09±0.05% for a 0.75Å passband, in the two
instruments respectively. The Hα absorption corresponds to
∼1.2Rp, which implies an expanded atmosphere, as a result of the gas
heating caused by the irradiation received from the host star. For
Hβ and Hγ only HARPS-N covers this wavelength range,
measuring an absorption depth of 0.28±0.06 and 0.21±0.07%,
respectively. For CaII, only CARMENES covers this wavelength range
measuring an absorption depth of 0.28±0.05, 0.41±0.05 and
0.27±0.06% for CaII λ8498Å, λ8542Å and
λ8662Å lines, respectively. Three additional absorption
lines of FeII are observed in the transmission spectrum by HARPS-N
(partially covered by CARMENES), measuring an average absorption depth
of 0.08±0.04% (0.75Å passband). The results presented here are
consistent with theoretical models of ultra-hot Jupiters atmospheres,
suggesting the emergence of an ionised gas on the day-side of such
planets. Calcium and iron, together with other elements, are expected
to be singly ionised at these temperatures and be more numerous than
its neutral state. The Calcium triplet lines are detected here for the
first time in transmission in an exoplanet atmosphere. Description:
The transmission spectra and of MASCARA-2b/KELT-20b are presented.
Three transits with HARPS-North at TNG telescope were retrieved and
one transit with CARMENES at 3.5 telescope at CAHA Observatory. For
each spectral line the transmission spectra of MASCARA-2b/KELT-20b
after correcting the CLV + RME are presented here. We note that in
some cases the transmission spectrum of a specific line also includes
transmission lines located close to the main spectral line (e.g. in
case of NaI doublet). However, it is important to note that only the
main spectral line of each file (see files name) includes the CLV+RME
corrections. You need to work with specific files.
Description:
We observed a total of four transits of MASCARA-2b using the HARPS-N
and CARMENES high resolution spectrographs. One of these transits was
simultaneously observed with the Multicolour Simultaneous Camera for
studying Atmospheres of Transiting exoplanets 2 (MuSCAT2), a
four-colour simultaneous imager, in order to monitor possible stellar
activity. One additional epoch was observed with MuSCAT2 to reproduce
the results of the first observation.
Objects:
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RA (2000) DE Designation(s)
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19 38 38.74 +31 13 09.2 MASCARA-2b = KELT-20b
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ham2har.dat 37 1751 Hα transmission spectrum with HARPS-N data
ham2car.dat 37 1752 Hα transmission spectrum with CARMENES data
hbm2har.dat 37 1297 Hβ transmission spectrum with HARPS-N data
hgm2har.dat 37 1158 Hγ transmission spectrum with HARPS-N data
ca1m2car.dat 37 2268 CaII8498 transmission spectrum with CARMENES data
ca2m2car.dat 37 2280 CaII8542 transmission spectrum with CARMENES data
ca3m2car.dat 37 2312 CaII8662 transmission spectrum with CARMENES data
mgm2har.dat 37 1380 MgI5173 transmission spectrum with HARPS-N data
na1m2har.dat 37 1572 NaID2 transmission spectrum with HARPS-N data
na2m2har.dat 37 1574 NaID1 transmission spectrum with HARPS-N data
na1m2car.dat 37 1572 NaID2 transmission spectrum with CARMENES data
na2m2car.dat 37 1573 NaID1 transmission spectrum with CARMENES data
fe1m2har.dat 37 1339 FeII5018 transmission spectrum with HARPS-N data
fe2m2har.dat 37 1380 FeII5169 transmission spectrum with HARPS-N data
fe3m2har.dat 37 1419 FeII5316 transmission spectrum with HARPS-N data
fe3m2car.dat 37 3155 FeII5316 transmission spectrum with CARMENES data
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See also:
J/A+A/612/A57 : MASCARA-2 b (HD185603) light curves & spectra (Talens+, 2018)
J/A+A/616/A151 : MASCARA-2b NaI + Ha absorption lines (Casasayas-Barris+, 2018)
Byte-by-byte Description of file: *.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm lambda Wavelength in Angstroem
9- 22 E14.13 --- Flux Relative Flux in % (1)
24- 37 E14.13 --- e_Flux Error on Flux
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Note (1): The final transmission spectrum (F) is the result of a ratio between
spectra. We present the data in % with the continuum in the 0 level by
applying (F-1.0)*100.
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Acknowledgements:
Nuria Casasayas-Barris, nuriacb(at)iac.es
(End) Nuria Casasayas-Barris [IAC, Spain], Patricia Vannier [CDS] 08-Jul-2019