J/ApJ/982/13 Abundances of 17000 M dwarfs in SDSS-V (Behmard+, 2025)
A Data-driven M Dwarf Model and Detailed Abundances for ∼17,000 M Dwarfs
in SDSS-V.
Behmard A., Ness M.K., Casey A.R., Angus R., Cunha K., Souto D., Lu Y.,
Johnson J.A.
<Astrophys. J. 982, 13 (2025)>
=2025ApJ...982...13B 2025ApJ...982...13B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Stars, M-type ; Abundances
Keywords: Stellar abundances - M dwarf stars - High resolution spectroscopy
Abstract:
The cool temperatures of M dwarf atmospheres enable complex molecular
chemistry, making robust characterization of M dwarf compositions a
long-standing challenge. Recent modifications to spectral synthesis
pipelines have enabled more accurate modeling of M dwarf atmospheres,
but these methods are too slow for characterizing more than a handful
of stars at a time. Data-driven methods such as The Cannon are viable
alternatives, and can harness the information content of many M dwarfs
from large spectroscopic surveys. Here, we train The Cannon on M
dwarfs with FGK binary companions from the Sloan Digital Sky
Survey-V/Milky Way Mapper (SDSS-V/MWM), with spectra from the Apache
Point Observatory Galactic Evolution Experiment. The FGK-M pairs are
assumed to be chemically homogeneous and span -0.56<[Fe/H]<0.31dex.
The resulting model is capable of inferring M dwarf Teff and elemental
abundances for Fe, Mg, Al, Si, C, N, O, Ca, Ti, Cr, and Ni with median
uncertainties of 13 K and 0.018-0.029 dex, respectively. We test the
model by verifying that it reproduces the reported abundance values of
M dwarfs in open clusters and benchmark M dwarf data sets, as well as
the expected metallicity trends from stellar evolution. We apply the
model to 16,590 M dwarfs in SDSS-V/MWM and provide their detailed
abundances in our accompanying catalog.
Description:
Table 2 lists the properties of the 16590 M dwarfs in our SDSS-V/MWM
test set. The properties consist of all labels inferred from our
implementation of The Cannon (Teff, abundances for all elements of
interest, and flux model spectral fit chi2 values). The errors on
the Teff and abundance labels are the scatter in labels from
resampling from flux errors 10 times for each M dwarf. We also include
a teff_agree flag describing whether the photometric and The
Cannon-inferred Teff agree to within 2σ.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 172 16590 M Dwarf Test Set Properties
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 identifier (1)
21- 29 I9 --- SDSS SDSS identifier (1)
31- 34 I4 K Teff Effective temperature (1)
36- 40 F5.2 [-] [Fe/H] Log Fe/H abundance ratio (1)
42- 46 F5.2 [-] [Mg/H] Log Mg/H abundance ratio (1)
48- 52 F5.2 [-] [Al/H] Log Al/H abundance ratio (1)
54- 58 F5.2 [-] [Si/H] Log Si/H abundance ratio (1)
60- 64 F5.2 [-] [C/H] Log C/H abundance ratio (1)
66- 70 F5.2 [-] [O/H] Log O/H abundance ratio (1)
72- 76 F5.2 [-] [Ca/H] Log Ca/H abundance ratio (1)
78- 82 F5.2 [-] [Ti/H] Log Ti/H abundance ratio (1)
84- 88 F5.2 [-] [Cr/H] Log Cr/H abundance ratio (1)
90- 94 F5.2 [-] [N/H] Log N/H abundance ratio (1)
96-100 F5.2 [-] [Ni/H] Log Ni/H abundance ratio (1)
102-106 I5 --- Chi2 Flux model spectral fit χ2 value
108-112 A5 --- TempAgree [True/False ] Photometric & Cannon-inferred
Teff agree to within 2σ
114-117 F4.1 K e_Teff Uncertainty in Teff (2)
119-122 F4.2 [-] e_[Fe/H] Uncertainty in [Fe/H] (2)
124-127 F4.2 [-] e_[Mg/H] Uncertainty in [Mg/H] (2)
129-132 F4.2 [-] e_[Al/H] Uncertainty in [Al/H] (2)
134-137 F4.2 [-] e_[Si/H] Uncertainty in [Si/H] (2)
139-142 F4.2 [-] e_[C/H] Uncertainty in [C/H] (2)
144-147 F4.2 [-] e_[O/H] Uncertainty in [O/H] (2)
149-152 F4.2 [-] e_[Ca/H] Uncertainty in [Ca/H] (2)
154-157 F4.2 [-] e_[Ti/H] Uncertainty in [Ti/H] (2)
159-162 F4.2 [-] e_[Cr/H] Uncertainty in [Cr/H] (2)
164-167 F4.2 [-] e_[N/H] Uncertainty in [N/H] (2)
169-172 F4.2 [-] e_[Ni/H] Uncertainty in [Ni/H] (2)
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Note (1): The properties of the 16,590 M dwarfs in our SDSS-V/MWM test set.
The properties consist of all labels inferred from our implementation of
The Cannon (Teff, abundances for all elements of interest, and Chi2.
Note (2): Uncertainties on the Teff and abundances are the scatter in labels
from resampling from flux errors 10 times for each M dwarf.
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Acknowledgements:
Aida Behmard, aida.behmard(at)gmail.com
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 03-Aug-2026