J/MNRAS/478/4513 GALAH Survey DR2 (Buder+, 2018)
The GALAH Survey: second data release.
Buder S., Asplund M., Duong L., Kos J., Lind K., Ness M.K., Sharma S.,
Bland-hawthorn J., Casey A.R., De Silva G.M., D'orazi V., Freeman K.C.,
Lewis G.F., Lin J., Martell S.L., Schlesinger K.J., Simpson J.D.,
Zucker D.B., Zwitter T., Amarsi A.M., Anguiano B., Carollo D.,
Casagrande L., Cotar K., Cottrell P.L., Da Costa G., Gao X.D., Hayden M.R.,
Horner J., Ireland M.J., Kafle P.R., Munari U., Nataf D.M., Nordlander T.,
Stello D., Ting Y.-S., Traven G., Watson F., Wittenmyer R.A., Wyse R.F.G.,
Yong D., Zinn J.C., Zerjal M., (the Galah collaboration)
<Mon. Not. R. Astron. Soc., 478, 4513-4552 (2018)>
=2018MNRAS.478.4513B 2018MNRAS.478.4513B (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Milky Way ; Photometry, infrared ; Abundances
Keywords: surveys - the Galaxy - methods: observational -
methods: data analysis - stars: fundamental parameters -
stars: abundances
Abstract:
The Galactic Archaeology with HERMES (GALAH) survey is a large-scale
stellar spectroscopic survey of the Milky Way, designed to deliver
complementary chemical information to a large number of stars covered
by the Gaia mission. We present the GALAH second public data release
(GALAH DR2) containing 342 682 stars. For these stars, the GALAH
collaboration provides stellar parameters and abundances for up to 23
elements to the community. Here we present the target selection,
observation, data reduction, and detailed explanation of how the
spectra were analysed to estimate stellar parameters and element
abundances. For the stellar analysis, we have used a multistep
approach. We use the physics-driven spectrum synthesis of Spectroscopy
Made Easy (SME) to derive stellar labels (Teff, logg, [Fe/H],
[X/Fe], vmic, vsini, AKS) for a representative training set of
stars. This information is then propagated to the whole sample with
the data-driven method of The Cannon. Special care has been exercised
in the spectral synthesis to only consider spectral lines that have
reliable atomic input data and are little affected by blending lines.
Departures from local thermodynamic equilibrium (LTE) are considered
for several key elements, including Li, O, Na, Mg, Al, Si, and Fe,
using 1D marcs stellar atmosphere models. Validation tests including
repeat observations, Gaia benchmark stars, open and globular clusters,
and K2 asteroseismic targets lend confidence to our methods and
results. Combining the GALAH DR2 catalogue with the kinematic
information from Gaia will enable a wide range of Galactic Archaeology
studies, with unprecedented detail, dimensionality, and scope.
Description:
This is the second data release of the GALAH survey.
Data for the GALAH survey are taken with the HERMES spectrograph on
the 3.9-metre Anglo-Australian Telescope (AAT) at Siding Spring
Observatory. HERMES is a fibre-fed high-resolution (R=28000)
spectrograph optimized to do Galactic archaeology from a 4m class
telescope, with four discrete optical wavelength channels covering
4713-4903Å, 5648-5873Å, 6478-6737Å, and 7585-7887Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 931 342682 GALAH DR2 catalog
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See also:
https://galah-survey.org/ : GALAH Home Page
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- StarId 2MASS ID number by default
(HHMMSSss+DDMMSSs, UCAC4 ID number if
2MASS unavailable (begins with UCAC4-)
(star_id)
18- 32 I15 --- sobjectId Unique per-observation star ID
(sobject_id)
34- 52 I19 --- GaiaId ?=-1 Gaia DR2 identifier (gaia_id)
54- 61 A8 --- ndfclass Observation type (MFOBJECT (regular
observation) or MFFLX (benchmark
observation)) (ndfclass)
63- 66 I4 --- FieldId GALAH field identification number
(field_id)
68- 77 F10.6 deg RAdeg Right ascension from 2MASS (J2000)
(raj2000)
79- 88 F10.6 deg DEdeg Declination from 2MASS (J2000) (dej2000)
90- 95 F6.3 mag Jmag J magnitude from 2MASS (jmag)
97-102 F6.3 mag Hmag H magnitude from 2MASS (hmag)
104-109 F6.3 mag Kmag K magnitude from 2MASS (kmag)
111-116 F6.3 mag VmagJK Synthetic V magnitude calculated from JHK,
used for target selection (vmag_jk)
118-122 F5.3 mag e_Jmag Uncertainty in J magnitude, from 2MASS
(e_jmag)
124-128 F5.3 mag e_Hmag Uncertainty in H magnitude, from 2MASS
(e_hmag)
130-134 F5.3 mag e_Kmag Uncertainty in K magnitude, from 2MASS
(e_kmag)
136-147 F12.6 --- SNRC1 Signal to noise per pixel in the
HERMES blue channel (snr_c1)
149-160 F12.6 --- SNRC2 Signal to noise per pixel in the
HERMES green channel (snr_c2)
162-173 F12.6 --- SNRC3 Signal to noise per pixel in the
HERMES red channel (snr_c3)
175-186 F12.6 --- SNRC4 Signal to noise per pixel in the
HERMES IR channel (snr_c4)
188-195 F8.3 km/s RVsynt Barycentric radial velocity from
cross-correlation against synthetic
spectra (rv_synt)
197-201 F5.3 km/s e_RVsynt Uncertainty in rv_synt (ervsynt)
203-210 F8.3 km/s RVobst ? Radial velocity from internal
cross-correlation against data (rv_obst)
212-216 F5.3 km/s e_RVobst ? Uncertainty in rv_obst (ervobst)
218-225 F8.3 km/s RVnogrobst ? Radial velocity from internal
cross-correlation against data,
uncorrected for gravitational redshift
(rvnogrobst)
227-231 F5.3 km/s e_RVnogrobst ? Uncertainty in rvnogrobst
(ervnogr_obst)
233-239 F7.3 --- chi2cannon Summed chi-squared over all spectral
pixels (chi2_cannon)
241-251 F11.6 --- splabeldist Label distance similar to Ho et al.
(2017, Cat. J/ApJ/836/5)
(splabeldistance)
253-255 I3 --- flagcannon Flags for spectrum information in a
bitmask format 0=No flag recommended
(flag_cannon) (1)
257-264 F8.3 K Teff Effective temperature (teff)
266-274 F9.3 K e_Teff Uncertainty of Teff (e_teff)
276-283 F8.5 [cm/s2] logg Surface gravity (logg)
285-291 F7.5 [cm/s2] e_logg Uncertainty of logg (e_logg)
293-300 F8.5 [-] [Fe/H] Iron abundance (not overall metallicity
[M/H]) (fe_h)
302-308 F7.5 [-] e_[Fe/H] Uncertainty in [Fe/H] (efeh)
310-315 F6.3 km/s vmic Microturbulence velocity (vmic)
317-321 F5.3 km/s e_vmic Uncertainty in vmic (e_vmic)
323-329 F7.3 km/s vsini Line of sight rotational velocity (vsini)
331-335 F5.3 km/s e_vsini Uncertainty in vsini (e_vsini)
337-347 E11.5 [-] [alpha/Fe] ? α enhancement, determined as an
error-weighted combination of Mg, Si, Ca,
Ti abundances (alpha_fe)
349-359 E11.5 [-] e_[alpha/Fe] ? Uncertainty in alpha_fe (ealphafe)
361-371 E11.5 [-] [Li/Fe] Abundance [Li/Fe] for element Li (li_fe)
373-383 E11.5 [-] e_[Li/Fe] Uncertainty in Li/Fe] (elixfe)
385 I1 --- f_[Li/Fe] indicating difficulty in abundance
determination in a bitmask format
(flaglife) (2)
387-397 E11.5 [-] [C/Fe] Abundance [X/Fe] for element C (c_fe)
399-409 E11.5 [-] e_[C/Fe] Uncertainty in [C/Fe] (ecfe)
411 I1 --- f_[C/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagcfe) (2)
413-423 E11.5 [-] [O/Fe] Abundance [O/Fe] for element O (o_fe)
425-435 E11.5 [-] e_[O/Fe] Uncertainty in [O/Fe] (eofe)
437 I1 --- f_[O/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagofe) (2)
439-449 E11.5 [-] [Na/Fe] Abundance [Na/Fe] for element Na (na_fe)
451-461 E11.5 [-] e_[Na/Fe] Uncertainty in [Na/Fe] (enafe)
463 I1 --- f_[Na/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagnafe) (2)
465-475 E11.5 [-] [Mg/Fe] ? Abundance [Mg/Fe] for element Mg (mg_fe)
477-487 E11.5 [-] e_[Mg/Fe] ? Uncertainty in [Mg/Fe] (emgfe)
489 I1 --- f_[Mg/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagmgfe) (2)
491-501 E11.5 [-] [Al/Fe] ? Abundance [Al/Fe] for element Al (x_fe)
503-513 E11.5 [-] e_[Al/Fe] ? Uncertainty in x_fe (exfe)
515 I1 --- f_[Al/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagxfe) (2)
517-527 E11.5 [-] [Si/Fe] ? Abundance [Si/Fe] for element Si (si_fe)
529-539 E11.5 [-] e_[Si/Fe] ? Uncertainty in [Si/Fe] (esife)
541 I1 --- f_[Si/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagsife) (2)
543-553 E11.5 [-] [K/Fe] ? Abundance [K/Fe] for element K (k_fe)
555-565 E11.5 [-] e_[K/Fe] ? Uncertainty in [K/Fe] (ekfe)
567 I1 --- f_[K/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagkfe) (2)
569-579 E11.5 [-] [Ca/Fe] Abundance [Ca/Fe] for element Ca (ca_fe)
581-591 E11.5 [-] e_[Ca/Fe] Uncertainty in [Ca/Fe] (ecafe)
593 I1 --- f_[Ca/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagcafe) (2)
595-605 E11.5 [-] [Sc/Fe] ? Abundance [Sc/Fe] for element Sc (sc_fe)
607-617 E11.5 [-] e_[Sc/Fe] ? Uncertainty in [Sc/Fe] (escfe)
619 I1 --- f_[Sc/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagscfe) (2)
621-631 E11.5 [-] [Ti/Fe] Abundance [Ti/Fe] for element Ti (ti_fe)
633-643 E11.5 [-] e_[Ti/Fe] Uncertainty in [Ti/Fe] (etife)
645 I1 --- f_[Ti/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagtife) (2)
647-657 E11.5 [-] [V/Fe] ? Abundance [V/Fe] for element V (v_fe)
659-669 E11.5 [-] e_[V/Fe] ? Uncertainty in [V/Fe] (evfe)
671 I1 --- f_[V/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagvfe) (2)
673-683 E11.5 [-] [Cr/Fe] ? Abundance [Cr/Fe] for element Cr (cr_fe)
685-695 E11.5 [-] e_[Cr/Fe] ? Uncertainty in [Cr/Fe] (ecrfe)
697 I1 --- f_[Cr/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagcrfe) (2)
699-709 E11.5 [-] [Mn/Fe] Abundance [Mn/Fe] for element Mn (mn_fe)
711-721 E11.5 [-] e_[Mn/Fe] Uncertainty in [Mn/Fe] (emnfe)
723 I1 --- f_[Mn/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagmnfe) (2)
725-735 E11.5 [-] [Co/Fe] Abundance [Co/Fe] for element Co (co_fe)
737-747 E11.5 [-] e_[Co/Fe] Uncertainty in [Co/Fe] (ecofe)
749 I1 --- f_[Co/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagcofe) (2)
751-761 E11.5 [-] [Ni/Fe] ? Abundance [Ni/Fe] for element Ni (ni_fe)
763-773 E11.5 [-] e_[Ni/Fe] ? Uncertainty in [Ni/Fe] (enife)
775 I1 --- f_[Ni/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagnife) (2)
777-787 E11.5 [-] [Cu/Fe] Abundance [Cu/Fe] for element Cu (cu_fe)
789-799 E11.5 [-] e_[Cu/Fe] Uncertainty in [Cu/Fe] (ecufe)
801 I1 --- f_[Cu/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagcufe) (2)
803-813 E11.5 [-] [Zn/Fe] ? Abundance [Zn/Fe] for element Zn (zn_fe)
815-825 E11.5 [-] e_[Zn/Fe] ? Uncertainty in [Zn/Fe] (eznfe)
827 I1 --- f_[Zn/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagznfe) (2)
829-839 E11.5 [-] [Y/Fe] Abundance [Y/Fe] for element Y (y_fe)
841-851 E11.5 [-] e_[Y/Fe] Uncertainty in [Y/Fe] (eyfe)
853 I1 --- f_[Y/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagyfe) (2)
855-865 E11.5 [-] [Ba/Fe] ? Abundance [Ba/Fe] for element Ba (ba_fe)
867-877 E11.5 [-] e_[Ba/Fe] ? Uncertainty in [Ba/Fe] (ebafe)
879 I1 --- f_[Ba/Fe] indicating difficulty in abundance
determination in a bitmask format
(flagbafe) (2)
881-891 E11.5 [-] [La/Fe] Abundance [La/Fe] for element La (la_fe)
893-903 E11.5 [-] e_[La/Fe] Uncertainty in [La/Fe] (elafe)
905 I1 --- f_[La/Fe] indicating difficulty in abundance
determination in a bitmask format
(flaglafe) (2)
907-917 E11.5 [-] [Eu/Fe] ? Abundance [Eu/Fe] for element Eu (eu_fe)
919-929 E11.5 [-] e_[Eu/Fe] ? Uncertainty in [Eu/Fe] (eeufe)
931 I1 --- f_[Eu/Fe] indicating difficulty in abundance
determination in a bitmask format
(flageufe) (2)
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Note (1): flagcannon as follows:
+1 (1st bit raised) = The Cannon starts to extrapolate.
For some stars the values could be incorrect
+2 (2nd bit raised) = The chi2 of the best fitting model spectrum is
significantly higher or lower
+4 (3rd bit raised) = Reduction flag raised
+8 (4th bit raised) = Binary star
+16 (5th bit raised) = Negative flux
+32 (6th bit raised) = Oscillating continuum
+64 (7th bit raised) = General reduction issues
+128 (8th bit raised) = Emission lines
Note (2): Abundance flag as follows:
0 = No flag recommended
+1 (1st bit raised) = Line strength below 2-sigma upper limit
+2 (2nd bit raised) = The Cannon starts to extrapolate.
For some stars the values could be incorrect
+4 (3rd bit raised) = The chi2 of the best fitting model spectrum is
significantly higher or lower
+8 (4th bit raised) = flag_cannon is not 0
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History:
Copied at https://datacentral.org.au/teamdata/GALAH/public
(End) Patricia Vannier [CDS] 02-Jan-2019