J/A+A/695/A47 Variable stars in VVV globulars. III. (Alonso-Garcia+, 2025)
Variable stars in the VVV globular clusters.
III. RR Lyrae stars in the inner Galactic globular clusters.
Alonso-Garcia J., Smith L.C., Sanders J.L., Minniti D., Catelan M.,
Aravena Rojas G., Carballo-Bello J.A., Fernandez-Trincado J.G.,
Ferreira Lopes C.E., Garro E.R., Guo Z., Hempel M., Lucas P.W.,
Majaess D., Saito R.K., Vivas A.K.
<Astron. Astrophys. 695, A47 (2025)>
=2025A&A...695A..47A 2025A&A...695A..47A (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, variable ; Stars, distances ;
Photometry, infrared
Keywords: stars: variables: RR Lyrae - globular clusters: general -
globular clusters: individual: UKS 1 -
globular clusters: individual: VVV-CL160
Abstract:
High reddening near the Galactic plane hampers observations and proper
characterization of the globular clusters (GCs) located toward the
inner regions of the Milky Way.
The VISTA Variables in the Via Lactea (VVV) survey observed the
Galactic bulge and adjacent disk for several years, providing
multi-epoch, near-infrared images for 41 Galactic GCs. Detecting RR
Lyrae variable stars belonging to these GCs will aid in their accurate
parameterization.
By fully leveraging the astrometric, photometric, and variability VVV
catalogs, we searched for RR Lyrae stars associated with GCs. Our
selection criteria, based on proper motions, proximity to the cluster
centers, and distances inferred from their
period-luminosity-metallicity relations, enable us to accurately
identify the RR Lyrae population in these GCs and determine color
excesses and distances to these poorly studied GCs in a homogeneous
manner. Since the VVV catalogs cover from the innermost regions of the
GCs to their outskirts, we can provide a comprehensive picture of the
entire RR Lyrae population in these GCs.
We have discovered significant RR Lyrae populations in two highly
reddened Galactic GCs: UKS 1 and VVV-CL160, previously unknown to host
RR Lyrae stars. Additionally, we have detected one RR Lyrae candidate
in each of Terzan 4 and Terzan 9, also new to RR Lyrae detection. We
further confirm and increase the number of RR Lyrae stars detected in
22 other low-latitude Galactic GCs. The RR Lyrae distances place most
of these GCs within the Galactic bulge, aligning well with the few GCs
in our sample with reliable Gaia or Hubble Space Telescope
measurements. However, most of the VVV GCs lack accurate Gaia
distances, and literature distances are generally significantly
smaller than those derived in this work. As a byproduct of our
analysis, we have obtained the proper motions for all the VVV GCs,
independently confirming Gaia results, except for two of the most
reddened GCs: UKS 1 and 2MASS-GC02.
Description:
In the current paper, the third in the series, we conducted a study of
Galactic GCs located toward the innermost regions of the Galaxy to
search for their RR Lyrae variable stars. Using the recent VIVACE and
VIRAC2 catalogs, both based on VVV near-infrared observations, we
explored the presence of these classical pulsators in the 41 GCs
within the VVV survey footprint. To determine membership for each GC,
we developed a methodology that incorporates proper motions, projected
proximity to the cluster center, and distance moduli derived from the
period-luminosity-metallicity relations.
Our study found RR Lyrae variable stars in 26 of the sampled VVV GCs.
Our membership assignments largely align with those from recent
studies in the literature for most of the RR Lyrae stars. Notably, our
analysis led to the discovery of unreported RR Lyrae stars in 16 VVV
GCs, including the first detection of several of these classic
pulsators in the highly reddened clusters UKS 1 and VVV-CL160. We also
identified one RR Lyrae star as a potential candidate in each of
Terzan 4 and Terzan 9.
Table D.2 presents a comprehensive list of the RR Lyrae stars in the
various VVV globular clusters (GCs), along with their positions and
photometric characteristics from the VIVACE database, as well as their
proper motions from the VIRAC2 database.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
clusters.dat 55 26 List of studied clusters
tabled2.dat 191 303 RR Lyrae stars in the various VVV globular
clusters
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See also:
V/150 : Updated catalog of variable stars in globular clusters
(Clement+ 2017)
J/MNRAS/509/2566 : VIVACE, VIrac VAriable Classification Ensemble
(Molnar+, 2022)
J/AJ/149/99 : Variable stars in VVV globulars. I. (Alonso-Garcia+, 2015)
J/A+A/651/A47 : Variable stars in VVV globulars. II. (Alonso-Garcia+, 2021)
Byte-by-byte Description of file: clusters.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Cluster name
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 22 F5.2 s RAs Right ascension (J2000)
24 A1 --- DE- Declination sign (J2000)
25- 26 I2 deg DEd Declination (J2000)
28- 29 I2 arcmin DEm Declination (J2000)
31- 34 F4.1 arcsec DEs Declination (J2000)
36- 45 A10 --- AName Alternative name
47- 55 A9 --- Cluster Cluster name as in table D2
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tabled2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Cluster Globular cluster name
11- 17 I7 --- VIVACE Identifier according to the VIVACE catalog
(2022MNRAS.509.2566M 2022MNRAS.509.2566M, Cat. J/MNRAS/509/2566)
19- 23 A5 --- CVSGC Identifier according to the CVSGC catalog
(2001AJ....122.2587C 2001AJ....122.2587C, Cat. V/150)
25- 38 I14 --- VIRAC2 Identifier according to the VIRAC2 catalog
(2025MNRAS.536.3707S 2025MNRAS.536.3707S)
40- 41 I2 h RAh Right ascension (J2000)
43- 44 I2 min RAm Right ascension (J2000)
46- 50 F5.2 s RAs Right ascension (J2000)
52 A1 --- DE- Declination sign (J2000)
53- 54 I2 deg DEd Declination (J2000)
56- 57 I2 arcmin DEm Declination (J2000)
59- 62 F4.1 arcsec DEs Declination (J2000)
64- 68 F5.2 arcmin Dist Projected distance to the cluster center
70- 77 F8.6 d Per Period of variation
79- 83 F5.3 mag AmpKs Amplitude of variation in the Ks band
86- 91 F6.3 mag Zmag ? Mean Z band magnitude
94- 98 F5.3 mag e_Zmag ? Uncertainty in the mean Ks band magnitude
101-106 F6.3 mag Ymag ? Mean Y band magnitude
109-113 F5.3 mag e_Ymag ? Uncertainty in the mean Ks band magnitude
116-121 F6.3 mag Jmag ? Mean J band magnitude
124-128 F5.3 mag e_Jmag ? Uncertainty in the mean Ks band magnitude
130-135 F6.3 mag Hmag Mean H band magnitude
137-141 F5.3 mag e_Hmag Uncertainty in the mean Ks band magnitude
143-148 F6.3 mag Ksmag Mean Ks band magnitude
150-154 F5.3 mag e_Ksmag Uncertainty in the mean Ks band magnitude
156-161 F6.2 mas/yr pmRA Proper motion in Right Ascension
163-166 F4.2 mas/yr e_pmRA Uncertainty in proper motion in RA
168-173 F6.2 mas/yr pmDE Proper motion in Declination
175-178 F4.2 mas/yr e_pmDE Uncertainty in proper motion in Declination
180-184 A5 --- Type RR Lyrae variable subtype (RRab or RRc)
188-191 A4 --- Flag Globular cluster membership flag (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
0 = marks those RR Lyrae stars consider cluster bonafide members
1 = marks those RR Lyrae stars whose membership is dubious
2 = marks those RR Lyrae stars which appear in the CVSGC, but our
analysis considers as non-members
3 = marks those RR Lyrae stars with mismatch type between VIVACE
and OGLE/CVSGC
--------------------------------------------------------------------------------
Acknowledgements:
Javier Alonso-Garcia, javier.alonso(at)uantof.cl
References:
Alonso-Garcia et al., Paper I 2015AJ....149...99A 2015AJ....149...99A, Cat. J/AJ/149/99
Alonso-Garcia et al., Paper II 2021A&A...651A..47A 2021A&A...651A..47A, Cat. J/A+A/651/A47
(End) Patricia Vannier [CDS] 03-Feb-2025