J/AJ/157/207 BVRcIc light curve observations for VZ Lib (Liao+, 2019)
Physical properties of the close-in tertiary in the southern triple-lined
system VZ Lib.
Liao W.-P., Qian S.-B., Sarotsakulchai T.
<Astron. J., 157, 207 (2019)>
=2019AJ....157..207L 2019AJ....157..207L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Binaries, eclipsing ;
Photometry, UBVRI
Keywords: binaries (including multiple): close - binaries: eclipsing -
stars: evolution - stars: individual (VZ Lib)
Abstract:
VZ Lib is a southern triple-lined system. By analyzing all available times
of light minima, orbital period changes are revisited in detail. We
discovered that the observed-calculated (O-C) curve shows a long-term
period decrease at a rate of dP/dt=-2.25x10-7 days/yr, revealing a mass
transfer from the more massive component to the less massive one. A cyclic
variation covering more than three cycles was discovered, which was
analyzed for the light-travel-time effect via the presence of the tertiary
companion. The cyclic variation has a short period of 2.96 (±0.04) yr
and a small semiamplitude of 0.0039 (±0.0004) days. The mass of the
third body was determined to be M3sini3=0.52 (±0.07) M☉ and
an orbital semimajor axis shorter than 1.93 (±0.31) au was obtained.
Orbital properties of this close-in companion should provide valuable
information on the formation of close binaries and stellar dynamical
interaction. New complete BVRcIc light curves of VZ Lib were obtained
and modeled with the Wilson-Devinney code. The light curves show a small
but significant O'Connell effect that was not detectable in 1981 and
2007 but in 2004, so we derived a new photometric solution with assuming
spot and a third light in the system. It is found that the light-curve
subtype changed from A-type to W-type, which was possibly caused by a
dark spot on the massive component. Our photometric solutions are in
agreement with the spectroscopic results given by previous authors.
Description:
CCD observations of VZ Lib were carried out on 2018 May 11 and 17 by using
the 1.0 m Cassegrainian reflecting telescope equipped with Andor DW436 2k
CCD at Yunnan Observatories (YNOs). Full BVRcIc light curves and
three eclipse times were obtained. The exposure durations were set as
40 s, 20 s, and 8 s for the B, V, and (RI)c bands, respectively. Bias and
flat-field images were obtained for using in preprocessing. All the CCD
images were processed with the DAOPHOT package of IRAF in a standard mode.
Differential magnitudes between VZ Lib and a comparison star were derived.
Objects:
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RA (ICRS) DE Designation(s)
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15 31 51.75 -15 41 10.2 VZ Lib = V* VZ Lib
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 22 1698 Light curve observations for VZ Lib
table3.dat 28 98 A total of 98 times of light minima for VZ Lib
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See also:
J/AJ/131/2986 : Multiplicity of contact binaries (Pribulla+, 2006)
J/A+A/465/943 : BVI and RV curves of 5 eclipsing binaries (Szalai+, 2007)
J/AJ/134/2353 : Observations of contact binaries (Rucinski+, 2007)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Filt [B V Rc Ic] Light curve filter
4- 15 F12.4 d HJD [2458250.1413/2458256.2813] Heliocentric Julian Date
17- 22 F6.3 mag Dmag [-2.975/-1.971] Differential magnitude in Filt
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d HJD [2428731.308/2458256.16677] Heliocentric Julian
Date of light minimum
15- 21 F7.5 d e_HJD [0.0001/0.003]? Uncertainty in HJD
23- 25 A3 --- Meth Observational method (1)
27- 28 I2 --- Ref [1/24] Reference (2)
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Note (1): Observational method as follows:
CCD = Charge-coupled device photometry;
Pe = Photoelectric photometry;
Pg = Photographic observation;
Vis = Visual observation.
Note (2): Reference as follows:
1 = O-C gateway;
2 = Claria & Lapasset (1981IBVS.2035....1C 1981IBVS.2035....1C);
3 = Nagai (2008, Var. Star Bull. 47 http://vsolj.cetus-net.org/no47.pdf);
4 = Nagai (2004, Var. Star Bull. 42 http://vsolj.cetus-net.org/no42.pdf);
5 = Krajci (2006IBVS.5690....1K 2006IBVS.5690....1K);
6 = Zejda et al. (2006IBVS.5741....1Z 2006IBVS.5741....1Z);
7 = Oglstrokoza et al. (2008IBVS.5843....1O 2008IBVS.5843....1O);
8 = Nagai (2007, Var. Star Bull. 45 http://vsolj.cetus-net.org/no45.pdf);
9 = Nagai (2009, Var. Star Bull. 48 http://vsolj.cetus-net.org/no48.pdf);
10 = Marino et al. (2010IBVS.5917....1M 2010IBVS.5917....1M);
11 = Nagai (2011,
Var. Star Bull. 51 http://vsolj.cetus-net.org/vsoljno51.pdf);
12 = Diethelm (2011IBVS.5992....1D 2011IBVS.5992....1D);
13 = Diethelm (2012IBVS.6029....1D 2012IBVS.6029....1D);
14 = Nagai (2013,
Var. Star Bull. 55 http://vsolj.cetus-net.org/vsoljno55.pdf);
15 = Honkova et al. (2013OEJV..160....1H 2013OEJV..160....1H);
16 = Nagai (2015,
Var. Star Bull. 59 http://vsolj.cetus-net.org/vsoljno59.pdf);
17 = Nagai (2016,
Var. Star Bull. 61 http://vsolj.cetus-net.org/vsoljno61.pdf);
18 = Nagai (2017,
Var. Star Bull. 63 http://vsolj.cetus-net.org/vsoljno63.pdf);
19 = Qian et al. (2008NewA...13...98Q 2008NewA...13...98Q);
20 = The present paper;
21 = Lu et al. (2001AJ....122..402L 2001AJ....122..402L);
22 = Bonnardeau (2009JAVSO..37..137B 2009JAVSO..37..137B);
23 = http://www.aavso.org/vsx/index.php?view=search.top
(Bob Nelson's O-C files, 2016);
24 = Szalai et al. (2007, J/A+A/465/943).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 08-Aug-2019