2020A&A...640A.131M


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.26CET19:58:20

2020A&A...640A.131M - Astronomy and Astrophysics, volume 640A, 131-131 (2020/8-1)

Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e.

MOLLIERE P., STOLKER T., LACOUR S., OTTEN G.P.P.L., SHANGGUAN J., CHARNAY B., MOLYAROVA T., NOWAK M., HENNING T., MARLEAU G.-D., SEMENOV D.A., VAN DISHOECK E., EISENHAUER F., GARCIA P., GARCIA LOPEZ R., GIRARD J.H., GREENBAUM A.Z., HINKLEY S., KERVELLA P., KREIDBERG L., MAIRE A.-L., NASEDKIN E., PUEYO L., SNELLEN I.A.G., VIGAN A., WANG J., DE ZEEUW P.T. and ZURLO A.

Abstract (from CDS):


Context. Clouds are ubiquitous in exoplanet atmospheres and they represent a challenge for the model interpretation of their spectra. When generating a large number of model spectra, complex cloud models often prove too costly numerically, whereas more efficient models may be overly simplified.
Aims. We aim to constrain the atmospheric properties of the directly imaged planet HR 8799e with a free retrieval approach.
Methods. We used our radiative transfer code petitRADTRANS for generating the spectra, which we coupled to the PyMultiNest tool. We added the effect of multiple scattering which is important for treating clouds. Two cloud model parameterizations are tested: the first incorporates the mixing and settling of condensates, the second simply parameterizes the functional form of the opacity.
Results. In mock retrievals, using an inadequate cloud model may result in atmospheres that are more isothermal and less cloudy than the input. Applying our framework on observations of HR 8799e made with the GPI, SPHERE, and GRAVITY, we find a cloudy atmosphere governed by disequilibrium chemistry, confirming previous analyses. We retrieve that C/O=0.60–0.08+0.07. Other models have not yet produced a well constrained C/O value for this planet. The retrieved C/O values of both cloud models are consistent, while leading to different atmospheric structures: either cloudy or more isothermal and less cloudy. Fitting the observations with the self-consistent Exo-REM model leads to comparable results, without constraining C/O.
Conclusions. With data from the most sensitive instruments, retrieval analyses of directly imaged planets are possible. The inferred C/O ratio of HR 8799e is independent of the cloud model and thus appears to be a robust. This C/O is consistent with stellar, which could indicate that the HR 8799e formed outside the CO2 or CO iceline. As it is the innermost planet of the system, this constraint could apply to all HR 8799 planets.

Abstract Copyright: © P. Mollière et al. 2020

Journal keyword(s): methods: numerical - planets and satellites: atmospheres - radiative transfer - instrumentation: spectrographs

Simbad objects: 6

goto Full paper

goto View the reference in ADS

Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 25335 * 03 59 41.9513224401 -43 11 31.824780841   9.99 8.94     K0III 8 0
2 HD 25535 ** 04 02 03.4498649369 -34 28 55.805892173   7.35 6.73     G1/2V 56 2
3 * bet Pic b Pl 05 47 17.0876901 -51 03 59.441135           ~ 358 1
4 * 51 Peg b Pl 22 57 27.9804167474 +20 46 07.782240714           ~ 537 1
5 HD 218396 El* 23 07 28.7156905667 +21 08 03.302133882   6.21 5.953     F0+VkA5mA5 916 0
6 HD 218396e Pl 23 07 28.7156905667 +21 08 03.302133882           ~ 136 1

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2020A&A...640A.131M and select 'bookmark this link' or equivalent in the popup menu


2020.11.26-19:58:20

© Université de Strasbourg/CNRS

    • Contact