J/A+A/660/A35 VVV survey. Long-period variable stars (Nikzat+, 2022)
The VVV survey: Long-period variable stars.
I. Photometric catalog of ten VVV/OGLE tiles.
Nikzat F., Ferreira Lopes C.E., Catelan M., Contreras Ramos R., Zoccali M.,
Rojas-Arriagada A., Braga V.F., Minniti D., Borissova J., Becker I.
<Astron. Astrophys. 660, A35 (2022)>
=2022A&A...660A..35N 2022A&A...660A..35N (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, variable ; Photometry, infrared
Keywords: catalogs - Galaxy: bulge - Galaxy: halo - Galaxy: structure -
stars: AGB and post-AGB - stars: variables: general
Abstract:
Long-period variable stars (LPVs) are pulsating red giants, primarily
in the asymptotic giant branch phase, and they include both Miras and
semi-regular variables (SRVs). Their period-age and period-luminosity
relations enable us to trace different stellar populations, as they
are intrinsically very bright and cover a wide range in distances and
ages. The purpose of this study is to establish a census of LPV stars
in a region close to the Galactic center, using the six-year database
of the Vista Variables in the Via Lactea (VVV) ESO Public Survey, as
well as to describe the methodology that was employed to search for
and characterize LPVs using VVV data. Near-IR surveys such as VVV
provide a unique opportunity to probe the high-extinction innermost
regions of the Milky Way. The detection and analysis of the
intrinsically bright Miras in this region could provide us with an
excellent probe of the properties of the Milky Way far behind its
bulge. We used point-spread function photometry for all available
Ks-band images in ten VVV tiles, covering 16.4deg2 in total,
overlapping fields observed in the course of the Optical Gravitational
Lensing Experiment (OGLE)-III survey. We designed a method to select
LPV candidates, and we used the known variables from OGLE-III and
other known variables from the literature to test our approach. The
reduced chi2 statistic, along with the flux-independent index Kfi,
were used in our analysis. The Lomb-Scargle period search method,
Fourier analysis, template fitting, and visual inspection were then
performed to refine our sample and characterize the properties of the
stars included in our catalog. A final sample of 130 Mira candidates,
of which 129 are new discoveries, was thus obtained, with periods in
the range between about 80 and 1400 days. Moreover, a sample of 1116
LPV candidates is also presented, whose periods are however not
sufficiently constrained by the available data. A fraction of the
latter may eventually turn out to be SRVs. Ages are measured for these
stars based on a reassessment of the period-age relations available in
the literature. The Miras in our catalog include 18 stars satisfying
the requirements to serve as reliable distance indicators and which
are not saturated in the VVV Ks-band images. Their distances are
accordingly derived and discussed. A number of objects that are
seemingly placed far behind the Milky Way's bulge was detected.
Description:
Photometric parameters for 130 Miras and 1013 LPV+ candidates in the
central regions of the Milky Way are presented. For each star, VVV
IDs, flag, Heliocentric Julian Dates (HJDs), mags, error-mags and
bandpass are given in the VVV-PSF photometry table. In addition, for
each LPV+ candidate, VVV IDs, OGLE IDs, coordinates, mean magnitudes
in each of J, H, and Ks, and amplitude in Ks are provided in the
VVV-PSF LPV+ candidates table.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tableb1.dat 73 130 Catalog of Miras
tableb2.dat 63 1013 Catalog of VVV-PSF LPV+ candidates
tablea1.dat 43 105440 VVV-PSF Photometry Mira and LPV+ candidates
(for 1013 LPV+ candidates and 130 Mira)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 I12 --- VVVID VVV ID
14- 22 F9.5 deg RAdeg Right Ascension (J2000)
24- 32 F9.5 deg DEdeg Declination (J2000)
34- 38 F5.2 mag Jmag ? Magnitude in J band
40- 43 F4.2 mag AJ ? Amplitude in J band
45- 49 F5.2 mag Hmag ? Magnitude in H band
51- 54 F4.2 mag AH ? Amplitude in H band
56- 60 F5.2 mag Ksmag ? Magnitude in Ks band
63- 66 F4.2 mag AKs Amplitude in Ks band
68- 73 F6.1 d Per Period
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 I12 --- VVVID VVV ID
14- 19 I6 --- OGLEID ? OGLE-III ID
21- 29 F9.5 deg RAdeg Right Ascension (J2000)
31- 39 F9.5 deg DEdeg Declination (J2000)
41- 45 F5.2 mag Jmag ? Magnitude in J band
47- 51 F5.2 mag Hmag ? Magnitude in H band
53- 57 F5.2 mag Ksmag Magnitude in Ks band
60- 63 F4.2 mag AKs Amplitude in Ks band
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 I12 --- VVVID VVV ID
14 A1 --- n_VVVID [*] * for Mira
16- 27 F12.6 d HJD Heliocentric Julian date (HJD-2400000)
29- 34 F6.3 mag mag Magnitude in Band
36- 40 F5.3 mag e_mag Magnitude-error
42- 43 A2 --- Band [J H Ks] Bandpass
--------------------------------------------------------------------------------
Acknowledgements:
Fatemeh Nikzat, fnikzat(at)uc.cl
(End) Fatemeh Nikzat [PUC, Chile], Patricia Vannier [CDS] 12-Jan-2022