Open AccessVariable Stars in the Giant Satellite Galaxy Antlia 2
Author(s) -
A. Katherina Vivas,
C. E. Martı́nez-Vázquez,
A. R. Walker,
Vasily Belokurov,
Ting S. Li,
Denis Erkal
Publication year - 2022
Publication title -
astrophysical journal/the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.3847/1538-4357/ac43bd
Subject(s) - rr lyrae variable , physics , astrophysics , astronomy , cepheid variable , galaxy , local group , stars , dwarf galaxy , satellite galaxy , variable star , globular cluster
We report 350 pulsating variable stars found in four DECam fields (∼12 deg 2 ) covering the Antlia 2 satellite galaxy. The sample of variables includes 318 RR Lyrae stars and eight anomalous Cepheids in the galaxy. Reclassification of several objects designated previously to be RR Lyrae as anomalous Cepheids get rid of the satellite’s stars intervening along the line of sight. This in turn removes the need for prolific tidal disruption of the dwarf, in agreement with the recently updated proper motion and pericenter measurements based on Gaia EDR3. There are also several bright foreground RR Lyrae stars in the field, and two distant background variables located ∼45 kpc behind Antlia 2. We found RR Lyrae stars over the full search area, suggesting that the galaxy is very large and likely extends beyond our observed area. The mean period of the RR ab in Antlia 2 is 0.599 days, while the RR c have a mean period of 0.368 days, indicating the galaxy is an Oosterhoff-intermediate system. The distance to Antlia 2 based on the RR Lyrae stars is 124.1 kpc ( μ 0 = 20.47) with a dispersion of 5.4 kpc. We measured a clear distance gradient along the semimajor axis of the galaxy, with the southeast side of Antlia 2 being ∼13 kpc farther away from the northwest side. This elongation along the line of sight is likely due to the ongoing tidal disruption of Ant 2.