DOI: 10.5281/zenodo.15393987
title: Isochrone ages for ~3 million stars with the second Gaia data release

description: Overview

The catalogue of ages, distances and extinctions associated with the publication Sanders & Das (2018)

We provide a catalogue of the combined results from all surveys complete with the Gaia DR2 source_id for each entry. We provide a full description of the columns (including their units) in Table B1 of Sanders & Das (2018) -- listed below. For each survey, we include a unique identifier (APOGEE: APOGEE_ID, LAMOST: obsid, RAVE:raveid, GES:CNAME, GALAH: sobject_id, SEGUE: specobjid) and we provide a field survey with a string detailing which survey the entry comes from. Note that we have not removed duplicate stars that were observed by two separate surveys (e.g. RAVE and RAVE-On). For each star we include the cross-matched Gaia DR2 source_id, the angular separation of the cross-match and the photometric bands used in the pipeline. The table is saved as an astropy table (The Astropy Collaboration et al. 2018) in hdf format, and can be simply read with from astropy.table import Table; data = Table.read(’file’);. A description of the column and structure of the table is available in data.meta[’COMMENT’]. 

Table B1 from Sanders & Das (2018):



Format of provided catalogue. We give the names, description, and unit of each provided quantity.




Name
Description
Unit




survey
String describing the spectroscopic survey from which the entry derives -- APOGEE, GALAH, GES, RAVEON, RAVEDR5, LAMOST, SEGUE
-


raveid
Unique ID for the RAVE (and RAVE-ON) catalogue
-


APOGEE_ID
Unique ID for the APOGEE catalogue
-


obsid
Unique ID for the LAMOST catalogue
-


sobject_id
Unique ID for the GALAH catalogue
-


CNAME
Unique ID for the GES catalogue
-


specobjid
Unique ID for the SEGUE catalogue
-


source_id
Cross-matched Gaia DR2 source ID
-


angular_separation
On-sky separation between spectroscopic catalogue entry and Gaia DR2 cross-match (epoch corrected if proper motion has been considered)
arcsec


ra
Right ascension from spectroscopic catalogue
degree


dec
Declination from spectroscopic catalogue
degree


mag_use
Comma-separated string giving photometry used in pipeline: J, H, K are 2MASS bands, G, GBP, GRP are Gaia bands, gP, rP, iP are Pan-STARRS bands, g, r, i are SDSS bands, Jv, Hv, Kv are VISTA bands
-




Primary outputs




Name
Description
Unit




dm
Distance modulus
mag


dist
Distance
kpc


par
Parallax (not Gaia DR2 parallax)
mas


log10_age
Base-10 logarithm of age
log10(Gyr)


mass
(Initial) Mass
M☉


Z
Metallicity
dex


log10_av
Base-10 logarithm of V-band extinction
log10(mag)


log10_teff
Base-10 logarithm of effective temperature
log10(K)


logg
Surface gravity
log10(cm/s²)




Auxiliary outputs




Name
Description
Unit




l
Galactic longitude
rad


b
Galactic latitude
rad


s
Distance derived from dm column
kpc


vlos
Line-of-sight velocity
km/s


mu_l
Proper motion in Galactic longitude
mas/yr


mu_b
Proper motion in Galactic latitude
mas/yr


R
Galactocentric cylindrical polar radius
kpc


phi
Galactocentric cylindrical polar angle (zero at solar position increasing in direction opposite to solar azimuthal velocity)
rad


z
Galactic height
kpc


vR
Galactocentric cylindrical radial velocity
km/s


vphi
Galactocentric azimuthal velocity (positive for Sun and decreasing phi)
km/s


vz
Galactocentric vertical velocity
km/s


JR
Radial action
kpc km/s


Lz
z-component of angular momentum (positive for Sun)
kpc km/s


Jz
Vertical action
kpc km/s


Rc
Galactocentric radius of circular orbit with angular momentum Lz
kpc


*_err
Corresponding uncertainty for each field
-


**corr
Correlations in derived quantities
-




Flags




Name
Description
Unit




flag
Non-zero if pipeline has failed (see text for meaning of each value)
-


duplicated
1 if duplicate Gaia source_id (see text for how we select the source to keep)
-


best
1 if flag=0, duplicated=0 and valid Gaia source_id
-