J/ApJ/886/10 Dwarfs or giants? Stellar metallicities & distances (Thomas+, 2019)
Dwarfs or giants?
Stellar metallicities and distances from ugrizG multiband photometry.
Thomas G.F., Annau N., Mcconnachie A., Fabbro S., Teimoorinia H., Cote P.,
Cuillandre J.-C., Gwyn S., Ibata R.A., Starkenburg E., Carlberg R.,
Famaey B., Fantin N., Ferrarese L., Henault-brunet V., Jensen J.,
Lancon A., Lewis G.F., Martin N.F., Navarro J.F., Reyle C.,
Sanchez-janssen R.
<Astrophys. J., 886, 10-10 (2019)>
=2019ApJ...886...10T 2019ApJ...886...10T (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, giant ; Stars, dwarfs ; Abundances, [Fe/H] ;
Stars, distances ; Photometry
Keywords: distance measure - metallicity - Milky Way Galaxy -
Milky Way stellar halo - red giant stars - stellar photometry
Abstract:
We present a new fully data-driven algorithm that uses photometric
data from the Canada-France Imaging Survey (CFIS; u), Pan-STARRS 1
(PS1; griz), and Gaia (G) to discriminate between dwarf and giant
stars and to estimate their distances and metallicities. The algorithm
is trained and tested using the Sloan Digital Sky Survey (SDSS)/SEGUE
spectroscopic data set and Gaia photometric/astrometric data set. At
[Fe/H]←1.2, the algorithm succeeds in identifying more than 70% of
the giants in the training/test set, with a dwarf contamination
fraction below 30% (with respect to the SDSS/SEGUE data set). The
photometric metallicity estimates have uncertainties better than
0.2dex when compared with the spectroscopic measurements. The
distances estimated by the algorithm are valid out to a distance of at
least ∼80kpc without requiring any prior on the stellar distribution
and have fully independent uncertainties that take into account both
random and systematic errors. These advances allow us to estimate
these stellar parameters for approximately 12 million stars in the
photometric data set. This will enable studies involving the chemical
mapping of the distant outer disk and the stellar halo, including
their kinematics using the Gaia proper motions. This type of algorithm
can be applied in the southern hemisphere to the first release of LSST
data, thus providing an almost complete view of the external
components of our Galaxy out to at least ∼80kpc. Critical to the
success of these efforts will be ensuring well-defined spectroscopic
training sets that sample a broad range of stellar parameters with
minimal biases. A catalog containing the training/test set and all
relevant parameters within the public footprint of CFIS is available
online.
Description:
Inputs and outputs of the training and test sets used by our machine
learning algorithm to estimate photometrically the type, the distances
and the metallicty of stars using the Canada-France Imaging Survey
(CFIS; u), Pan-STARRS 1 (PS1; griz) and Gaia (G).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 1372 44506 Training/testing catalog, dwarf or giant
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See also:
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 11 F11.7 deg RAdeg Right ascension (J2000) (RA)
13- 22 F10.7 deg DEdeg Declination (J2000) (Dec)
24- 41 F18.15 mag ucfis u-band photometry (u_cfis)
43- 60 F18.15 mag u0cfis Dereddened u-band photometry (u0_cfis)
62- 82 F21.19 mag e_ucfis Uncertainty on the u-band photometry
(du_cfis)
84- 101 F18.15 mag gPS PS1 mean g-PSF photometry (g_PS)
103- 120 F18.15 mag g0PS Dereddened PS1 mean g-PSF photometry
(g0_PS)
122- 142 E21.16 mag e_gPS Uncertainty on the g-band photometry
(dg_PS)
144- 161 F18.15 mag rPS PS1 mean r-PSF photometry (r_PS)
163- 180 F18.15 mag r0PS Dereddened PS1 mean r-PSF photometry
(r0_PS)
182- 202 E21.16 mag e_rPS Uncertainty on the r-band photometry
(dr_PS)
204- 221 F18.15 mag iPS PS1 mean i-PSF photometry (i_PS)
223- 240 F18.15 mag i0PS Dereddened PS1 mean i-PSF photometry
(i0_PS)
242- 262 E21.16 mag e_iPS Uncertainty on the i-band photometry
(di_PS)
264- 281 F18.15 mag zPS PS1 mean z-PSF photometry (z_PS)
283- 300 F18.15 mag z0PS Dereddened PS1 mean z-PSF photometry
(z0_PS)
302- 322 E21.16 mag e_zPS Uncertainty on the z-band photometry
(dz_PS)
324- 343 F20.15 mag yPS ?=-999 PS1 mean y-PSF photometry (y_PS)
345- 364 F20.15 mag y0PS ?=-999 Dereddened PS1 mean y-PSF
photometry (y0_PS)
366- 387 E22.16 mag e_yPS ?=-999 Uncertainty on the y-band
photometry (dy_PS)
389- 406 F18.15 mag Gmag Gaia G-band photometry (G_gaia)
408- 425 F18.15 mag G0mag Dereddened Gaia G-band photometry
(G0_gaia)
427- 447 E21.16 mag e_Gmag Uncertainty on the Gaia G-band
photometry (dG_gaia)
449- 466 F18.15 mag BPmag ? Gaia BP-band photometry (BP_gaia)
468- 485 F18.15 mag BP0mag ? Dereddened Gaia BP-band photometry
(BP0_gaia)
487- 507 E21.16 mag e_BPmag ? Uncertainty on the Gaia BP-band
photometry (dBP_gaia)
509- 526 F18.15 mag RPmag ? Gaia RP-band photometry (RP_gaia)
528- 545 F18.15 mag RP0mag ? Dereddened Gaia RP-band photometry
(RP0_gaia)
547- 567 E21.16 mag e_RPmag ? Uncertainty on the Gaia RP-band
photometry (dRP_gaia)
569- 590 E22.16 mas plx ? Gaia parallax (parallax)
592- 611 F20.18 mas e_plx ? Uncertainty on the Gaia parallax
(dparallax)
613- 634 E22.16 mas/yr pmRA ? Gaia proper motion in R.A. direction,
pmRA*DE (pmra)
636- 655 F20.18 mas/yr e_pmRA ? Uncertainty on the Gaia proper motion
in R.A. direction (dpmra)
657- 678 E22.16 mas/yr pmDE ? Gaia proper motion in declination
direction (pmdec)
680- 699 F20.18 mas/yr e_pmDE ? Uncertainty on the Gaia proper motion
in declination direction (dpmdec)
701- 721 F21.19 mag E(B-V) Extinction from Schlegel et al.
(1998ApJ...500..525S 1998ApJ...500..525S) (EBV)
723- 742 F20.18 --- Pdwarf [0/1] Probability of being a dwarf
(proba_dwarf)
744- 763 F20.18 --- Pgiant [0/1] Probability of being a giant
(=1-proba_dwarf) (proba_giant)
765- 786 E22.16 --- e_Pgiant ? Uncertainty on the probability to be a
dwarf/giant (dproba_giant)
788- 809 E22.16 [-] [Fe/H]p Predicted photometric metallicity
(equal to feh_dwarf if proba_dwarf>0.5
and to feh_giant if proba_giant>0.5)
(feh_pred)
811- 831 F21.19 [-] e_[Fe/H]p Systematic error on the predicted
photometric metallicity (dfehpredsys)
833- 853 E21.16 [-] e_[Fe/H]pph Photometric uncertainty on the predicted
photometric metallicity
(dfehpredphoto)
855- 875 E21.16 mag GMAGp Predicted absolute magnitude (equal to
MG_dwarf if proba_dwarf>0.5 and to
MG_giant if proba_giant>0.5) (MG_pred)
877- 897 F21.19 mag e_GMAGp Systematic error on the predicted
absolute magnitude (dMGpredsys)
899- 919 F21.19 mag e_GMAGpph Uncertainty on the predicted absolute
magnitude (dMGpredphoto)
921- 942 E22.16 [-] [Fe/H]pdw Predicted photometric metallicity using
the dwarf calibration (feh_dwarf)
944- 964 F21.19 [-] e_[Fe/H]pdw Systematic error on the predicted
photometric metallicity of the dwarfs
(dfehdwarfsys)
966- 986 E21.16 [-] e_[Fe/H]pdwph Photometric uncertainty on the predicted
photometric metallicity of the dwarfs
(dfehdwarfphoto)
988-1005 F18.16 mag GMAGpdw Predicted absolute magnitude using the
dwarf calibration (MG_dwarf)
1007-1027 F21.19 mag e_GMAGpdw Systematic error on the predicted
absolute magnitude of the dwarfs
(dMGdwarfsys)
1029-1049 F21.19 mag e_GMAMApdwph Uncertainty on the predicted absolute
magnitude of dwarfs (dMGdwarfphoto)
1051-1072 E22.16 [-] [Fe/H]pg Predicted photometric metallicity using
the giant calibration (feh_giant)
1074-1094 F21.19 [-] e_[Fe/H]pg Systematic error on the predicted
photometric metallicity of the giants
(dfehgiantsys)
1096-1116 F21.19 [-] e_[Fe/H]pgph Photometric uncertainty on the predicted
photometric metallicity of the giants
(dfehgiantphoto)
1118-1139 E22.16 mag GMAGpg Predicted absolute magnitude using the
giant calibration (MG_giant)
1141-1161 F21.19 mag e_GMAGpg Systematic error on the predicted
absolute magnitude of the giants
(dMGgiantsys)
1163-1183 F21.19 mag e_GMAGpgph Uncertainty on the predicted absolute
magnitude of giants (dMGgiantphoto)
1185-1204 F20.17 kpc Distp Heliocentric distance using the
predicted absolute magnitude (kpc)
(dist_pred)
1206-1228 F23.19 mag GMAG ? Absolute magnitude computed from the
Gaia parallaxes (MG_gaia)
1230-1252 F23.18 mag e_GMAG ? Uncertainty on the absolute magnitude
from Gaia parallaxes (dMG_gaia)
1254-1272 I19 --- objID Object ID from SDSS/SEGUE (objid)
1274-1292 I19 --- specobjID Spectrocopic ID from SDSS/SEGUE
(specobjID)
1294-1301 F8.3 K Teff Adopted effective temperature from
SDSS/SEGUE (in Kelvin) (Teffadop)
1303-1314 F12.7 K e_Teff Uncertainty on the adopted effective
temperature from SDSS/SEGUE
(Teffadopunc)
1316-1324 F9.7 [cm/s2] logg Adopted surface gravity from SDSS/SEGUE
(loggadop)
1326-1336 E11.6 [cm/s2] e_logg Uncertainty on the adopted surface
gravity from SDSS/SEGUE (loggadopunc)
1338-1349 E12.6 [-] [Fe/H] Adopted spectroscopic metallicity from
SDSS/SEGUE (FeHadop)
1351-1361 E11.6 [-] e_[Fe/H] Uncertainty on the adopted spectroscopic
metallicity from SDSS/SEGUE
(FeHadopunc)
1363-1372 F10.5 --- SNR Spectroscopic S/N from SDSS/SEGUE (snr)
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Acknowledgements:
Guillaume Thomas, guillaume.thomas.astro(at)gmail.com
(End) Patricia Vannier [CDS] 27-Feb-2020