High-resolution Elemental Abundance Measurements of Cool JWST Planet Hosts Using AutoSpecFit: An Application to the Sub-Neptune K2-18b's Host M Dwarf

被引：3

作者：

Hejazi, Neda ^{[1
,2
]}

Crossfield, Ian J. M. ^{[1
]}

Souto, Diogo ^{[3
]}

Brande, Jonathan ^{[1
]}

Nordlander, Thomas ^{[4
,5
]}

Marfil, Emilio ^{[6
,7
,8
]}

Cunha, Katia ^{[9
,10
]}

Coria, David R. ^{[1
]}

Maas, Zachary G. ^{[11
]}

Polanski, Alex S. ^{[1
]}

Hinkel, Natalie R. ^{[12
]}

Hand, Joseph E. ^{[1
]}

机构：

[1] Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA

[2] Georgia State Univ, Dept Phys & Astron, Atlanta, GA 30303 USA

[3] Univ Fed Sergipe, Dept Fis, Av Marcelo Deda Chagas S-N, BR-49107230 Sao Cristovao, SE, Brazil

[4] Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia

[5] ARC Ctr Excellence All Sky Astrophys 3 Dimens, Canberra, ACT 2611, Australia

[6] Univ Complutense Madrid, Dept Fis Tierra & Astrofis, Madrid 28040, Spain

[7] Univ Complutense Madrid, Fac Ciencias Fis, IPARCOS UCM Unidad Fis Particulas & Cosmos UCM, Madrid 28040, Spain

[8] Univ Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany

[9] Univ Arizona, Dept Astron, Tucson, AZ 85721 USA

[10] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA

[11] Indiana Univ, Dept Astron, Bloomington, IN 47405 USA

[12] Louisiana State Univ, Dept Phys & Astron, Baton Rouge, LA 70803 USA

来源：

ASTROPHYSICAL JOURNAL | 2024年 / 973卷 / 01期

基金：

澳大利亚研究理事会;

关键词：

PROTOPLANETARY DISKS; MODEL ATMOSPHERES; CARMENES SEARCH; STELLAR CHARACTERIZATION; EFFECTIVE TEMPERATURE; CHEMICAL ABUNDANCES; FORMATION HISTORY; MINI-NEPTUNE; SUPER-EARTH; STARS;

D O I：

10.3847/1538-4357/ad61dc

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present an in-depth, high-resolution spectroscopic analysis of the M dwarf K2-18, which hosts a sub-Neptune exoplanet in its habitable zone. We show our technique to accurately normalize the observed spectrum, which is crucial for a proper spectral fitting. We also introduce a new automatic, line-by-line, model-fitting code, AutoSpecFit, which performs an iterative chi 2 minimization process to measure individual elemental abundances of cool dwarfs. We apply this code to the star K2-18, and measure the abundance of 10 elements: C, O, Na, Mg, Al, K, Ca, Sc, Ti, and Fe. We find these abundances to be moderately supersolar, except for Fe, with a slightly subsolar abundance. The accuracy of the inferred abundances is limited by the systematic errors due to uncertain stellar parameters. We also derive the abundance ratios associated with several planet-building elements such as Al/Mg, Ca/Mg, Fe/Mg, and (a solar-like) C/O = 0.568 +/- 0.026, which can be used to constrain the chemical composition and the formation location of the exoplanet. On the other hand, the planet K2-18 b has attracted considerable interest, given the JWST measurements of its atmospheric composition. Early JWST studies reveal an unusual chemistry for the atmosphere of this planet, which is unlikely to be driven by formation in a disk of unusual composition. The comparison between the chemical abundances of K2-18 b from future JWST analyses and those of the host star can provide fundamental insights into the formation of this planetary system.

引用

页数：21