J/MNRAS/504/654 Short-period binaries in the inner VVV bulge (Botan+, 2021)
Unveiling short-period binaries in the inner VVV bulge.
Botan E., Saito R.K., Minniti D., Kanaan A., Contreras Ramos R.,
Ferreira T.S., Gramajo L.V., Navarro M.G.
<Mon. Not. R. Astron. Soc., 504, 654-666 (2021)>
=2021MNRAS.504..654B 2021MNRAS.504..654B (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Binaries, eclipsing ; Galactic center ;
Infrared sources ; Photometry, infrared ; Extinction ; Reddening
Keywords: surveys - binaries: eclipsing - Galaxy: bulge - Galaxy: disc -
Galaxy: stellar content
Abstract:
Most of our knowledge of the structure of the Milky Way has come from
the study of variable stars. Among these variables, mimicking the
periodic variation of pulsating stars, are eclipsing binaries. These
stars are important in astrophysics because they allow us to directly
measure the radii and masses of the components, as well as the
distance to the system, thus being useful in studies of Galactic
structure alongside pulsating RR Lyrae and Cepheids. Using the
distinguishing features of their light curves, one can identify them
using a semi-automated process. In this work, we present a strategy to
search for eclipsing variables in the inner VVV bulge across an area
of 13.4 deg2 within 1.68° < l < 7.53° and
-3.73° < b < -1.44°, corresponding to the VVV tiles b293-b296
and b307-b310. We accurately classify 212 previously unknown eclipsing
binaries, including six very reddened sources. A preliminary analysis
suggests that these eclipsing binaries are located in the most obscured
regions of the foreground disc and bulge of the Galaxy. This search is
therefore complementary to other variable-star searches carried out at
optical wavelengths.
Description:
Since short time eclipsing binaries present distinguishing features in
the light curves, algorithms can be trained to select these objects
automatically. Here we present the result of a systematic search for
eclipsing binaries (EBs) in the inner VVV bulge area (inner bulge in
Milky Way center).
Our observational datas come from the VISTA Variables in Via Lactea
(VVV) public survey in near-infrared Ks filter bands. A total of eight
tiles in the inner bulge have been observed for 300 epochs. These
tiles cover a total area of ∼13.4 deg2 and allowed us to extract a
total of 11 621 729 light curves.
Since this work is focused on short-period variables, in the period
range of RR Lyrae stars (P ≤ 1 d), we limited our sample to that
extent, leaving us with 23 857 variables in the period range from
0.1-1 d (see details in section 3 target selection). Moreover, we
attemp to study only asymmetric eclipsing binaries, so we classify and
select our sources doing Fourier fit on light curves (see section 4
eclipsing binary classification). Thus, it allows us to automatically
keep 850 bona fide asymmetric EBs. Hereafter, we compared our
resulting sample with the OGLE-IV VSX (Watson et al. 2006, Cat. B/vsx),
VVV-CVSC catalogues (Ferreira Lopes et al. 2020MNRAS.496.1730F 2020MNRAS.496.1730F) and
Gaia DR2 (Cat. I/345) (see section 5). With cross matched catalogues
method we identify 212 new EBs across eight inner VVV tiles covering
an area of ∼13.4 deg2.
Here we provide a table (tablea1.dat) of general informations about the
new 212 selected EBs. Coordinates are J2000 from the VVV catalogues,
the magnitudes and colours are from the same source (see Section 2).
For the period determination see Section 3. Extinction and reddening
are integrated along the line of sight values from BEAM (see
Section 5). A few of the (J - Ks) colours are missing because of
the absence of J-band measurements for the target in the VVV data.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 77 212 General information about the new EBs
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See also:
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-)
II/337 : VISTA Variables in the Via Lactea Survey DR1 (Saito+, 2012)
II/348 : VISTA Variable in the Via Lactea Survey DR2 (Minniti+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/376 : VISTA Variable in the Via Lactea Survey (VVV) DR4.2 (Minniti+, 2023)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- ID New EBs ID name (ID)
10- 18 F9.5 deg RAdeg Right ascension of the new EBs (J2000) (RA2000)
20- 28 F9.5 deg DEdeg Declination of the new EBs (J2000) (Dec2000)
30- 36 F7.5 d Per The periodic time of the new EBs (Period)
38- 42 F5.2 mag Ksmag Apparent magnitude in Ks filter (Ks)
44- 47 F4.2 mag e_Ksmag Mean error on Ksmag (Ksmagerror)
49- 52 F4.2 mag J-Ks ? Colour index of magnitude (J-Ks) (1)
54- 57 F4.2 mag e_J-Ks ? Mean error on J-Ks (J-Kserror) (1)
59- 62 F4.2 mag AKs Extinction on Ks band (Aks) (2)
64- 67 F4.2 mag e_AKs Mean error on Extinction (Akserror) (2)
69- 72 F4.2 mag E(J-Ks) Reddening (EJ-Ks) (2)
74- 77 F4.2 mag e_E(J-Ks) Mean error on Reddening (EJ-Kserror) (2)
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Note (1): A few of the (J - Ks) colours are missing because of the absence
of J-band measurements for the target in the VVV data.
Note (2): Extinction and reddening are integrated values from BEAM calculator
(Gonzalez et al. 2012A&A...543A..13G 2012A&A...543A..13G) and assuming
extinction law (Cardelli et al. 1989ApJ...345..245C 1989ApJ...345..245C).
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History:
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(End) Luc Trabelsi [CDS] 22-Apr-2024