J/ApJ/836/5 Abundances of LAMOST giants from APOGEE DR12 (Ho+, 2017)
Label transfer from APOGEE to LAMOST: precise stellar parameters for 450000
LAMOST giants.
Ho A.Y.Q., Ness M.K., Hogg D.W., Rix H.-W., Liu C., Yang F., Zhang Y.,
Hou Y., Wang Y.
<Astrophys. J., 836, 5-5 (2017)>
=2017ApJ...836....5H 2017ApJ...836....5H (SIMBAD/NED BibCode)
ADC_Keywords: Abundances ; Stars, giant ; Surveys ; Spectroscopy
Keywords: catalogs; methods: data analysis; methods: statistical;
stars: abundances; stars: fundamental parameters;
techniques: spectroscopic
Abstract:
In this era of large-scale spectroscopic stellar surveys, measurements
of stellar attributes ("labels," i.e., parameters and abundances) must
be made precise and consistent across surveys. Here, we demonstrate
that this can be achieved by a data-driven approach to spectral
modeling. With The Cannon, we transfer information from the APOGEE
survey to determine precise Teff, logg, [Fe/H], and [α/M] from
the spectra of 450000 LAMOST giants. The Cannon fits a predictive
model for LAMOST spectra using 9952 stars observed in common between
the two surveys, taking five labels from APOGEE DR12 as ground truth
Teff, logg, [Fe/H], [α/M], and K-band extinction Ak. The
model is then used to infer Teff, logg, [Fe/H], and [α/M] for
454180 giants, 20% of the LAMOST DR2 stellar sample. These are the
first [α/M] values for the full set of LAMOST giants, and the
largest catalog of [α/M] for giant stars to date. Furthermore,
these labels are by construction on the APOGEE label scale; for
spectra with S/N>50, cross-validation of the model yields typical
uncertainties of 70K in Teff, 0.1 in logg, 0.1 in [Fe/H], and 0.04
in [α/M], values comparable to the broadly stated, conservative
APOGEE DR12 uncertainties. Thus, by using "label transfer" to tie
low-resolution (LAMOST R∼1800) spectra to the label scale of a much
higher-resolution (APOGEE R∼22500) survey, we substantially reduce the
inconsistencies between labels measured by the individual survey
pipelines. This demonstrates that label transfer with The Cannon can
successfully bring different surveys onto the same physical scale.
Description:
The Large sky Area Multi-Object Spectroscopic Telescope (LAMOST) is a
low-resolution (R∼1800) optical (3650-9000Å) spectroscopic survey.
APOGEE is a high-resolution (R∼22500), high-S/N (S/N∼100), H-band
(15200-16900Å) spectroscopic survey, part of the Sloan Digital Sky
Survey III. Observations are conducted using a 300 fiber spectrograph
on the 2.5m Sloan Telescope at the Apache Point Observatory (APO) in
Sunspot, New Mexico (USA).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 139 454180 Stellar labels (Teff, logg, [Fe/H], and [α/M])
for 454180 stars, inferred by The Cannon directly
from LAMOST spectra
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See also:
V/149 : LAMOST DR2 catalogs (Luo+, 2016)
III/272 : RAVE 4th data release (Kordopatis+, 2013)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
III/218 : ELODIE archive (Prugniel+, 2001)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/ApJ/708/1628 : Diffuse interstellar bands. IV. (McCall+, 2010)
J/other/RAA/11.924 : Atmospheric parameters for 771 stars (Wu+, 2011)
J/A+A/525/A71 : Atmospheric parameters for 1273 stars (Wu+, 2011)
J/AJ/146/133 : Stellar parameters from SDSS-III APOGEE DR10 (Meszaros+, 2013)
J/AJ/150/187 : Abundances and stellar parameters of LAMOST stars (Lee+, 2015)
J/ApJ/798/110 : Equivalent widths of LAMOST metal-poor stars (Li+, 2015)
J/ApJ/808/16 : The Cannon: a new approach to determine abundances
(Ness+, 2015)
J/other/RAA/16.G10 : [alpha/Fe] ratios from LAMOST spectra (Li+, 2016)
J/AJ/152/6 : Param. of Kepler stars using LAMOST+seismic data (Wang+, 2016)
http://www.github.com/annayqho/TheCannon/ : The Cannon code in Python
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 45 A45 --- SpecID LAMOST unique identifier (format
"spec-{LMJD}-{PlanId}-sp{spId}-{FiberId}.fits")
47- 58 F12.8 deg RAdeg Right ascension in decimal degrees (J2000)
60- 70 F11.8 deg DEdeg Declination in decimal degrees (J2000)
72- 77 F6.1 K Teff [3622/5895] Effective temperature
79- 85 F7.4 [cm/s2] logg [-0.6/5.1] Log of surface gravity
87- 94 F8.5 [-] [Fe/H] [-2.8/0.9] Abundance of [Fe/H]
96-103 F8.5 [-] [a/M] [-0.2/0.5] [α/M] abundance
105-111 F7.1 K e_Teff [2/57094] Teff uncertainty
113-118 F6.4 [cm/s2] e_logg [0.0001/1.7] logg uncertainty
120-126 F7.5 [-] e_[Fe/H] [0.00001/1.1] [Fe/H] uncertainty
128-134 F7.5 [-] e_[a/M] [0.00001/0.6] [a/M] uncertainty
136-139 F4.2 --- Chi2 [0.02/10] Reduced χ2
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 07-Sep-2017