Korg: Fitting, Model Atmosphere Interpolation, and Brackett Lines
We describe several updates to Korg , a package for 1D LTE spectral synthesis of FGKM stars. Built-in functions to fit observed spectra via synthesis or equivalent widths make it easy to take advantage of Korg 's automatic differentiation. Comparison to a past analysis of 18 Sco shows that we o...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2024-01-01
|
| Series: | The Astronomical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-3881/ad19cc |
| _version_ | 1827368755043237888 |
|---|---|
| author | Adam J. Wheeler Andrew R. Casey Matthew W. Abruzzo |
| author_facet | Adam J. Wheeler Andrew R. Casey Matthew W. Abruzzo |
| author_sort | Adam J. Wheeler |
| collection | DOAJ |
| description | We describe several updates to Korg , a package for 1D LTE spectral synthesis of FGKM stars. Built-in functions to fit observed spectra via synthesis or equivalent widths make it easy to take advantage of Korg 's automatic differentiation. Comparison to a past analysis of 18 Sco shows that we obtain significantly reduced line-to-line abundance scatter with Korg . Fitting and synthesis are facilitated by a rigorously tested model atmosphere interpolation method, which introduces negligible error to synthesized spectra for stars with T _eff ≳ 4000 K. For cooler stars, atmosphere interpolation is complicated by the presence of molecules, though we demonstrate an adequate method for cool dwarfs. The chemical equilibrium solver has been extended to include polyatomic and charged molecules, extending Korg 's regime of applicability to M stars. We also discuss a common oversight regarding the synthesis of hydrogen lines in the infrared, and show that Korg 's Brackett line profiles are a much closer match to observations than others available. Documentation, installation instructions, and tutorials are available at https://github.com/ajwheeler/Korg.jl . |
| first_indexed | 2024-03-08T09:35:18Z |
| format | Article |
| id | doaj.art-e576d68bb3374e33bd745b2c35a061fe |
| institution | Directory Open Access Journal |
| issn | 1538-3881 |
| language | English |
| last_indexed | 2024-03-08T09:35:18Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astronomical Journal |
| spelling | doaj.art-e576d68bb3374e33bd745b2c35a061fe2024-01-30T10:06:11ZengIOP PublishingThe Astronomical Journal1538-38812024-01-0116728310.3847/1538-3881/ad19ccKorg: Fitting, Model Atmosphere Interpolation, and Brackett LinesAdam J. Wheeler0https://orcid.org/0000-0001-7339-5136Andrew R. Casey1https://orcid.org/0000-0003-0174-0564Matthew W. Abruzzo2https://orcid.org/0000-0002-7918-3086Department of Astronomy, Ohio State University , McPherson Laboratory, 140 West 18th Avenue, Columbus, Ohio, USA ; wheeler.883@osu.eduSchool of Physics & Astronomy, Monash University , Victoria, Australia; Center of Excellence for Astrophysics in Three Dimensions (ASTRO-3D) , AustraliaDepartment of Physics and Astronomy, University of Pittsburgh , 100 Allen Hall 3941 O’Hara Street, Pittsburgh, PA 15260, USAWe describe several updates to Korg , a package for 1D LTE spectral synthesis of FGKM stars. Built-in functions to fit observed spectra via synthesis or equivalent widths make it easy to take advantage of Korg 's automatic differentiation. Comparison to a past analysis of 18 Sco shows that we obtain significantly reduced line-to-line abundance scatter with Korg . Fitting and synthesis are facilitated by a rigorously tested model atmosphere interpolation method, which introduces negligible error to synthesized spectra for stars with T _eff ≳ 4000 K. For cooler stars, atmosphere interpolation is complicated by the presence of molecules, though we demonstrate an adequate method for cool dwarfs. The chemical equilibrium solver has been extended to include polyatomic and charged molecules, extending Korg 's regime of applicability to M stars. We also discuss a common oversight regarding the synthesis of hydrogen lines in the infrared, and show that Korg 's Brackett line profiles are a much closer match to observations than others available. Documentation, installation instructions, and tutorials are available at https://github.com/ajwheeler/Korg.jl .https://doi.org/10.3847/1538-3881/ad19ccSpectroscopyStellar atmospheresStellar photospheresStellar spectral linesStellar propertiesAstronomy software |
| spellingShingle | Adam J. Wheeler Andrew R. Casey Matthew W. Abruzzo Korg: Fitting, Model Atmosphere Interpolation, and Brackett Lines The Astronomical Journal Spectroscopy Stellar atmospheres Stellar photospheres Stellar spectral lines Stellar properties Astronomy software |
| title | Korg: Fitting, Model Atmosphere Interpolation, and Brackett Lines |
| title_full | Korg: Fitting, Model Atmosphere Interpolation, and Brackett Lines |
| title_fullStr | Korg: Fitting, Model Atmosphere Interpolation, and Brackett Lines |
| title_full_unstemmed | Korg: Fitting, Model Atmosphere Interpolation, and Brackett Lines |
| title_short | Korg: Fitting, Model Atmosphere Interpolation, and Brackett Lines |
| title_sort | korg fitting model atmosphere interpolation and brackett lines |
| topic | Spectroscopy Stellar atmospheres Stellar photospheres Stellar spectral lines Stellar properties Astronomy software |
| url | https://doi.org/10.3847/1538-3881/ad19cc |
| work_keys_str_mv | AT adamjwheeler korgfittingmodelatmosphereinterpolationandbrackettlines AT andrewrcasey korgfittingmodelatmosphereinterpolationandbrackettlines AT matthewwabruzzo korgfittingmodelatmosphereinterpolationandbrackettlines |