Variable star classification across the Galactic bulge and disc with the VISTA Variables in the Vía Láctea survey

Abstract

We present VIVACE, the VIrac VAriable Classification Ensemble, a catalogue of variable stars extracted from an automated classification pipeline for the Vista Variables in the Vía Láctea (VVV) infrared survey of the Galactic bar/bulge and southern disc. Our procedure utilises a two-stage hierarchical classifier to first isolate likely variable sources using simple variability summary statistics and training sets of non-variable sources from the Gaia early third data release, and then classify candidate variables using more detailed light curve statistics and training labels primarily from OGLE and VSX. The methodology is applied to point-spread-function photometry for $\sim 490$ million light curves from the VIRAC v2 astrometric and photometric catalogue resulting in a catalogue of $\sim 1.4$ million likely variable stars, of which $\sim 39,000$ are high-confidence (classification probability $>0.9$) RR Lyrae ab stars, $\sim 8000$ RR Lyrae c/d stars, $\sim 187,000$ detached/semi-detached eclipsing binaries, $\sim 18,000$ contact eclipsing binaries, $\sim 1400$ classical Cepheid variables and $\sim 2200$ Type II Cepheid variables. Comparison with OGLE-4 suggests a completeness of around $90\%$ for RRab and $\lesssim 60\%$ for RRc/d, and a misclassification rate for known RR Lyrae stars of around $1\%$ for the high confidence sample. We close with two science demonstrations of our new VIVACE catalogue: first, a brief investigation of the spatial and kinematic properties of the RR Lyrae stars within the disc/bulge, demonstrating the spatial elongation of bar-bulge RR Lyrae stars is in the same sense as the more metal-rich red giant population whilst having a slower rotation rate of $\sim 40{\mathrm{km}\mathrm{s}}^{-1}{\mathrm{kpc}}^{-1}$; and secondly, an investigation of the Gaia EDR3 parallax zeropoint using contact eclipsing binaries across the Galactic disc plane and bulge.

Accepted for publication in MNRAS, 27 pages, 23 figures, corresponding catalogue available at https://people.ast.cam.ac.uk/~jls/data/vproject/vivace_catalogue.fits

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Cited by in corpus (12)

• Mira variables in the Milky Way's nuclear stellar disc: discovery and classification
• VIRAC2: NIR Astrometry and Time Series Photometry for 500M+ Stars from the VVV and VVVX Surveys
• The extinction law in the inner $3\times 3$ deg${}^2$ of the Milky Way and the red clump absolute magnitude in the inner bar-bulge
• The most variable VVV sources: eruptive protostars, dipping giants in the Nuclear Disc and others
• Three Ultra-short Period Contact Eclipsing Binary Systems Mined from Massive Astronomical Surveys
• The VVV near-IR galaxy catalogue in a Northern part of the Galactic disc
• Semi-Supervised Classification and Clustering Analysis for Variable Stars
• Automated classification of eclipsing binary systems in the VVV Survey
• The first Palomar Gattini-IR catalog of J-band light curves: construction and public data release
• AGN candidates in the VVV near-IR galaxy catalogue
• M-dwarf stars in the b294 field from the VISTA Variables in the Vía Láctea (VVV)
• Infrared-excess sources in VVV: candidate debris discs, SED characterization, and variability analysis