J/ApJ/748/93 K-band spectra for 133 nearby M dwarfs (Rojas-Ayala+, 2012)
Metallicity and temperature indicators in M dwarf K-band spectra: testing new
and updated calibrations with observations of 133 solar neighborhood M dwarfs.
Rojas-Ayala B., Covey K.R., Muirhead P.S., Lloyd J.P.
<Astrophys. J., 748, 93 (2012)>
=2012ApJ...748...93R 2012ApJ...748...93R
ADC_Keywords: Abundances ; Effective temperatures ; Spectra, infrared ;
Spectral types ; Stars, M-type ; Equivalent widths
Keywords: stars: abundances - stars: fundamental parameters - stars: late-type
Abstract:
We present K-band spectra for 133 nearby (d < 33 pc) M dwarfs,
including 18 M dwarfs with reliable metallicity estimates (as inferred
from an FGK type companion), 11 M dwarf planet hosts, more than 2/3 of
the M dwarfs in the northern 8 pc sample, and several M dwarfs from
the LSPM catalog. From these spectra, we measure equivalent widths of
the Ca and Na lines, and a spectral index quantifying the absorption
due to H2O opacity (the H2O-K2 index). Using empirical spectral
type standards and synthetic models, we calibrate the H2O-K2 index
as an indicator of an M dwarf's spectral type and effective
temperature. We also present a revised relationship that estimates the
[Fe/H] and [M/H] metallicities of M dwarfs from their Na I, Ca I, and
H2O-K2 measurements. Comparisons to model atmosphere provide a
qualitative validation of our approach, but also reveal an overall
offset between the atomic line strengths predicted by models as
compared to actual observations. Our metallicity estimates also
reproduce expected correlations with Galactic space motions and
Hα emission line strengths, and return statistically identical
metallicities for M dwarfs within a common multiple system. Finally,
we find systematic residuals between our H2O-based spectral types
and those derived from optical spectral features with previously known
sensitivity to stellar metallicity, such as TiO, and identify the CaH1
index as a promising optical index for diagnosing the metallicities of
near-solar M dwarfs.
Description:
Near-infrared spectra of the 133 stars were obtained with the TripleSpec
spectrograph on the Palomar 200 inch Hale Telescope during several
observing runs between 2007 and 2010. TripleSpec at Palomar has no
moving parts and simultaneously acquires 5 cross-dispersed orders
covering 1.0-2.4um at a resolution of λ/Δλ∼2700.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 77 133 TripleSpec nearby M dwarf sample - source
properties
table3.dat 83 133 TripleSpec nearby M dwarf Sample - spectral
measurements
spectra/* . 133 1.88-2.46µm Spectra of the M dwarfs (FITS files)
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See also:
V/70 : Nearby Stars, Preliminary 3rd Version (Gliese+ 1991)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)
I/238 : Yale Trigonometric Parallaxes, Fourth Edition (van Altena+ 1995)
III/114 : Spectra of Late-Type Standards, 2.0-2.5 Microns (Kleinmann+ 1986)
J/MNRAS/403/1949 : UBV(RcIc)JHK photometry of HIP nearby stars (Koen+, 2010)
J/ApJ/704/975 : Rotational velocities for M dwarfs (Jenkins+, 2009)
J/ApJ/701/764 : Light curves for five M-dwarf stars (Fernandez+, 2009)
J/A+A/493/645 : Gl 176 radial velocities (Forveille+, 2009)
J/PASP/121/117 : Fe & Ti abundances of 12 M stars (Woolf+, 2009)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)
J/A+A/415/1153 : [Fe/H] for 98 extra-solar planet-host stars (Santos+, 2004)
J/AJ/123/3356 : PMSU nearby star spectroscopic survey. III. (Gizis+, 2002)
J/A+A/364/665 : Very low mass stars radial velocities (Segransan+, 2000)
J/A+A/331/581 : Rotation and activity in field M dwarfs (Delfosse+ 1998)
J/AJ/113/806 : M-Subdwarfs (Gizis 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name
14 A1 --- n_Name [abc] Alternative designation (G1)
16- 19 F4.1 pc Dist [1.8/41.9]? Star's distance
21- 25 F5.2 mag Vmag [7.49/19.74] V-band magnitude
27 I1 --- r_Vmag [1/8] Dist and Vmag reference (1)
29- 34 F6.3 mag Ksmag [3/11] 2MASS Ks-band magnitude
36- 46 A11 "YYYY/MMM/DD" Date Spectrum observation date
48- 51 I4 --- S/N [201/2079] Average signal-to-noise ratio
obtained in the K-band continuum
53- 67 A15 --- Comm Star comment
69- 95 A27 --- File FileName of individual spectrum in the
"spectra" subdirectory (column added by CDS)
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Note (1): Reference as follows:
1 = HIPPARCOS, van Leeuwen 2007, Cat. I/311;
2 = YALE, van Altena et al. 2001, Cat. I/238;
3 = PMSU, Reid et al. 1995, Cat. III/198;
4 = Koen et al. 2010, Cat. J/MNRAS/403/1949;
5 = Leggett 1992ApJS...82..351L 1992ApJS...82..351L;
6 = Bessel 1990A&AS...83..357B 1990A&AS...83..357B;
7 = Gould & Chaname 2004, Cat. J/ApJS/150/455;
8 = Gliese & Jahreiss Catalog of Nearby Star, Cat. V/70
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name
14 A1 --- n_Name [abc] Alternative designation (G1)
16- 20 F5.3 0.1nm EWNaI NaI equivalent width
22- 26 F5.3 0.1nm e_EWNaI EWNaI uncertainty
28- 32 F5.3 0.1nm EWCaI CaI equivalent width
34- 38 F5.3 0.1nm e_EWCaI EWCaI uncertainty
40- 44 F5.3 --- H2O-K2 H2O-K2 index (2)
46- 50 F5.3 --- e_H2O-K2 H20-K2 uncertainty
52 I1 --- SpT [0/9] M-spectral subtype
54- 57 I4 K Teff [2492/4031]? Effective temperature
59- 61 I3 K e_Teff [15/106]? Teff uncertainty
63- 67 F5.2 [Sun] [M/H] [-0.45/0.33] Overall metallicity (3)
69- 72 F4.2 [Sun] e_[M/H] [0.12] [M/H] uncertainty
74- 78 F5.2 [Sun] [Fe/H] [-0.64/0.46] [Fe/H] metallicity
80- 83 F4.2 [Sun] e_[Fe/H] [0.17/0.18] [Fe/H] uncertainty
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Note (2): Covey et al. (2010ApJ...722..971C 2010ApJ...722..971C) adopted the H2O-K index to
characterize the spectral types of highly reddened young stars from
moderate S/N spectra. We developed a modified H2O-index using two
new regions that do not show any noticeable atomic lines. This
H2O-K2 water index is defined in equation (5). See section 3.2 for
further explanations.
Note (3): See section 5.2 for the new K-band overall metallicity ([M/H])
calibration.
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Global notes:
Note (G1): Flag as follows:
a = LSPM J0011+5908.
b = 2MASS J18353790+3259545.
c = Stars with low quality K-band spectra.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 15-Oct-2013