Exoplines: Molecular Absorption Cross-section Database For Brown Dwarf And Giant Exoplanet Atmospheres

Gharib-Nezhad, Ehsan

Permalink

https://hdl.handle.net/2142/111451 Copy

Description

Title

Exoplines: Molecular Absorption Cross-section Database For Brown Dwarf And Giant Exoplanet Atmospheres

Author(s)

Gharib-Nezhad, Ehsan

Contributor(s)

• Batalha, Natasha E
• Marley, Mark S
• Freedman, Richard S
• Line, Michael R
• Iyer, Aishwarya

Issue Date

2021-06-23

Keyword(s)

Linelists

Abstract

Stellar, substellar, and planetary atmosphere models are all highly sensitive to the input absorption cross-sections and subject to errors arising from incomplete line lists and the lack of appropriate pressure-broadening parameters. Generational differences between various state-of-the-art stellar and planetary models are primarily because of incomplete and outdated atomic and molecular line lists. Addressing this, here we present a database of pre-computed molecular absorption cross-sections for all isotopologues of key atmospheric absorbers relevant to late-type stellar, brown dwarf, and planetary atmospheres: MgH, AlH, CaH, TiH, CrH, FeH, SiO, TiO, VO, and H$_2$O. The pressure and temperature ranges of the computed data are between 10$^{-6}$--3000 bar and 75--4000 K, and their spectral ranges are 0.25--330 \wn for many cases where possible. Some details on absorption cross-sections such as wing cut-off and pressure broadening have been either ignored or forgotten even though they have an instrumental impact on radiative transfer atmospheric modelings. Furthermore, for most molecules such as TiO, VO, and H$_2$O, multiple sets of cross-section data exist which lead to extensive biases and inaccuracies on the interpretation of observational data including uncertainty in the C/O ratio, thermal structure, and composition of exoplanetary atmospheres. In sum, we present (1) a database of pre-computed molecular absorption cross-sections to mitigate shortcomings for pre-existing incomplete line lists, and (2) quantify biases that arise when characterizing substellar/exoplanet atmospheres due to line list differences. Lastly, our team’s endeavors at NASA Ames research center to leverage these disagreements and concerns on cross-section data and the lack of sufficient pre-computed and evaluated dataset will be addressed. Our comprehensive database platform, MAESTRO, will be introduced.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111451

DOI

10.15278/isms.2021.WF04

Owning Collections