Atmospheric parameters and chemical abundances of young stars with APOGEE – I. Orion star-forming region

ABSTRACT We derive atmospheric parameters and chemical abundances in young G-, K-, and M-type stars (temperatures between 6500 and 3100 K) using infrared APOGEE-2 spectra. Atmospheric parameters were determined for 548 young stars in the Orion complex (Orion A, B, OB1, and $\lambda$ Ori) using the tonalli code. For 340 slow rotators ($v\sin i$ $\le$ 30 km s$^{-1}$), we derived C, Mg, Si, K, Ti, and Fe abundances using 19 atomic lines, MARCS model atmospheres, and bacchus. To mitigate the impact of circumstellar material, we excluded stars with infrared excess identified via 2MASS and WISE photometry. We find subsolar [X/H] abundance ratios, consistent across elements and among all four groups, suggesting a chemically homogeneous Orion complex. We computed [$\alpha$/Fe] from [Mg/Fe], [Si/Fe], and [Ti/Fe], obtaining a median of $-0.14 \pm 0.04$, about 0.10 dex lower than the value for nearby main-sequence stars ($-0.04 \pm 0.04$) at similar [Fe/H]. This result aligns with predictions from Galactic chemical evolution models. Furthermore, the median [C/H] abundance we derived for Orion agrees with previous estimations based on the analysis of the ionized gas of the Orion nebula. This work sets the stage for extending the analysis to stars with circumstellar material and higher rotational velocities, which will not only improve our understanding of Orion, but also provide critical insight into the formation and evolution of young stars, as well as the chemical evolution of the Milky Way.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-09-01
DOI
https://doi.org/10.1093/mnras/staf1445
Primary Topic
Astrophysics and Star Formation Studies
Type
article
Field-Weighted Citation Impact
0.00

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article

Atmospheric parameters and chemical abundances of young stars with APOGEE – I. Orion star-forming region

Jinyoung Serena Kim, Leticia Carigi, S. J. Wolk, José G. Fernández-Trincado et al.
Monthly Notices of the Royal Astronomical Society
Astrophysics and Star Formation Studies
article

Atmospheric parameters and chemical abundances of young stars with APOGEE – I. Orion star-forming region

Jinyoung Serena Kim, Leticia Carigi, S. J. Wolk, José G. Fernández-Trincado, Richard R. Lane, J. Eduardo Méndez-Delgado, Ricardo López–Valdivia, Guy S. Stringfellow, L. Adame, R. Pandey, Javier Serna, E. Sánchez, Bárbara Rojas-Ayala, S. Villanova, Marina Kounkel, Alexandre Roman–Lopes, C. Román-Zúñiga, Jesús Hernández, Keivan G. Stassun, Eduardo Zagala Lagunas, Jonathan C. Tan, Itzarel Herrnández-Aburto
article en

Abstract

ABSTRACT We derive atmospheric parameters and chemical abundances in young G-, K-, and M-type stars (temperatures between 6500 and 3100 K) using infrared APOGEE-2 spectra. Atmospheric parameters were determined for 548 young stars in the Orion complex (Orion A, B, OB1, and $\lambda$ Ori) using the tonalli code. For 340 slow rotators ($v\sin i$ $\le$ 30 km s$^{-1}$), we derived C, Mg, Si, K, Ti, and Fe abundances using 19 atomic lines, MARCS model atmospheres, and bacchus. To mitigate the impact of circumstellar material, we excluded stars with infrared excess identified via 2MASS and WISE photometry. We find subsolar [X/H] abundance ratios, consistent across elements and among all four groups, suggesting a chemically homogeneous Orion complex. We computed [$\alpha$/Fe] from [Mg/Fe], [Si/Fe], and [Ti/Fe], obtaining a median of $-0.14 \pm 0.04$, about 0.10 dex lower than the value for nearby main-sequence stars ($-0.04 \pm 0.04$) at similar [Fe/H]. This result aligns with predictions from Galactic chemical evolution models. Furthermore, the median [C/H] abundance we derived for Orion agrees with previous estimations based on the analysis of the ionized gas of the Orion nebula. This work sets the stage for extending the analysis to stars with circumstellar material and higher rotational velocities, which will not only improve our understanding of Orion, but also provide critical insight into the formation and evolution of young stars, as well as the chemical evolution of the Milky Way.

Monthly Notices of the Royal Astronomical SocietyVol. 543(1)
University of North Florida (US), University of Arizona (US), Universidad Autónoma de Baja California (MX), University of Tarapacá (CL), University of Colorado Boulder (US), Vanderbilt University (US), Universidad Católica del Norte (CL), Universidad Bernardo O'Higgins (CL), Laboratory for Atmospheric and Space Physics (US), Center for Astrophysics Harvard & Smithsonian (US), Atmospheric and Space Technology Research Associates (United States) (US), Astronomy and Space (AU), Instituto de Geofísica y Astronomía (CU), University of Virginia (US), Chalmers University of Technology (SE), University of La Serena (CL), University of Oklahoma (US), Universidad Nacional Autónoma de México (MX)
Smithsonian Institution, U.S. Department of Energy, Alfred P. Sloan Foundation, Yale University, Carnegie Institution of Washington, Vanderbilt University, Ohio State University, University of Utah, University of Washington, Johns Hopkins University, Carnegie Mellon University, University of Notre Dame, University of Portsmouth, New Mexico State University, York University, University of Oxford, Ministério da Ciência, Tecnologia e Inovação, Universidad Nacional Autónoma de México, Agencia Nacional de Investigación y Desarrollo, Max-Planck-Institut für Astrophysik, Max-Planck-Institut für Astronomie, Instituto de Astrofísica de Canarias, Office of Science, University of Colorado Boulder, Smithsonian Astrophysical Observatory, Leibniz-Gemeinschaft, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, Lawrence Berkeley National Laboratory
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Astrophysics and Star Formation Studies
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