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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 (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:
FileName Lrecl Records Explanations
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
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) : The Cannon code in Python Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
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
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 07-Sep-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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