2022A&A...657A..97M


Query : 2022A&A...657A..97M

2022A&A...657A..97M - Astronomy and Astrophysics, volume 657A, 97-97 (2022/1-1)

The strange case of Na I in the atmosphere of HD 209458 b. Reconciling low- and high-resolution spectroscopic observations.

MORELLO G., CASASAYAS-BARRIS N., ORELL-MIQUEL J., PALLE E., CRACCHIOLO G. and MICELA G.

Abstract (from CDS):


Aims. We aim to investigate the origin of the discrepant results reported in the literature about the presence of NaI in the atmosphere of HD 209458 b, based on low- and high-resolution transmission spectroscopy.
Methods. We generated synthetic planetary atmosphere models and we compared them with the transmission light curves and spectra observed in previous studies. Our models account for the stellar limb-darkening and Rossiter-McLaughlin (RM) effects, and contemplate various possible scenarios for the planetary atmosphere.
Results. We reconciled the discrepant results by identifying a range of planetary atmospheres that are consistent with previous low- and high-resolution spectroscopic observations. Either both datasets are interpreted as consistent with a total absence of NaI in the planetary atmosphere (with Hubble Space Telescope data being affected by limb darkening), or the terminator temperature of HD 209458 b has to have an upper limit of about 1000 K.In particular, we find that 1D transmission spectra with lower-than-equilibrium temperatures can also explain the previously reported detection of absorption signal at low resolution due to differential transit depth in adjacent bands, while the cores of the NaI D lines may be masked by the strong RM signal seen at high resolution. We also rule out high-altitude clouds, which would otherwise mask the absorption signal at low resolution, as the source of the discrepancies.
Conclusions. This work highlights the synergies between different observing techniques, specifically low- and high-resolution spectroscopy, to fully characterise transiting exoplanet systems.

Abstract Copyright: © ESO 2022

Journal keyword(s): planetary systems - planets and satellites: individual: HD 209458 b - planets and satellites: atmospheres - techniques: spectroscopic - methods: observational

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 HD 209458 V* 22 03 10.7727465312 +18 53 03.549393384   8.21 7.63     F9V 1070 1
2 HD 209458b Pl 22 03 10.7729598762 +18 53 03.548248479           ~ 1742 1

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2023.01.31-01:58:53

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