J/AJ/157/3 BVRI light curves of the binary QS Vir (Latkovic+, 2019)
Long-term spot stability in the post-common-envelope binary QS Vir.
Latkovic O., Cseki A., Djurasevic G., Essam A., Hamed A.S., Youssef S.M.
<Astron. J., 157, 3 (2019)>
=2019AJ....157....3L 2019AJ....157....3L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf ; Stars, dwarfs ; Binaries, eclipsing ;
Photometry, UBVRI ; Photometry, infrared
Keywords: binaries: close - binaries: eclipsing - stars: activity -
stars: fundamental parameters - stars: individual (QS Vir)
Abstract:
We observed the post-common-envelope eclipsing binary with a white dwarf
component, QS Vir, using the 1.88 m telescope of Kotammia Observatory
in Egypt. The new observations were analyzed together with all multicolor
light curves available online (sampling a period of 25 yr), using a
full-feature binary system modeling software based on Roche geometry.
This is the first time complete photometric modeling was done with most
of these data. QS Vir is a detached system, with the red dwarf component
underfilling its Roche lobe by a small margin. All light curves feature
out-of-eclipse variability that is associated with ellipsoidal variation,
mutual irradiation and irregularities in surface brightness of the tidally
distorted and magnetically active red dwarf. We tested models with one,
two, and three dark spots and found that one spot is sufficient to account
for the light curve asymmetry in all data sets, although this does not
rule out the presence of multiple spots. We also found that a single
spotted model cannot fit light curves observed simultaneously in different
filters. Instead, each filter requires a different spot configuration.
To thoroughly explore the parameter space of spot locations, we devised
a grid-search procedure and used it to find consistent solutions. Based on
this, we conclude that the dark spot responsible for light curve
distortions has been stable for the past 15 yr, after a major migration
that happened between 1993 and 2002, possibly due to a flip-flop event.
Description:
Photometric observations of QS Vir in Bessell BVRI filters were carried out
on six nights in 2015 March and on another two nights in 2016 March and
April with the EEV CCD 42-40 camera (2048x2048 pixels) cooled by liquid
nitrogen to -125°C and attached to the Newtonian focus of the 1.88 m
reflector telescope of Kottamia Observatory in Egypt. A total of 786 CCD
science frames (432 in 2015 and 354 in 2016) were obtained and reduced
using the Muniwin software package (http://c-munipack.sourceforge.net).
Observations in the VRI filters were done sequentially in four observing
sessions, and in the B filter separately in another four sessions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 81 3 Information about the variable, comparison,
and check stars (from the UCAC4 catalog,
Zacharias et al. 2012, Cat. I/322)
table3.dat 36 786 New BVRI light curves of QS Vir
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See also:
I/322 : UCAC4 Catalogue (Zacharias+, 2012)
J/PASJ/59/955 : UBVRI differential photometry of BH Vir (Xiang+, 2007)
J/A+A/513/L7 : Post common envelope binaries from SDSS. VIII
(Schreiber+, 2010)
J/MNRAS/413/1121 : SDSS post-common envelope binaries. X
(Rebassa-Mansergas+ 2011)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Star name
12- 27 A16 --- UCAC4 UCAC4 designation (UCAC4 FFF-NNNNNN)
29- 30 I2 h RAh Hour of Right Ascension (J2000)
32- 33 I2 min RAm Minute of Right Ascension (J2000)
35- 40 F6.3 s RAs Second of Right Ascension (J2000)
42 A1 --- DE- Sign of the Declination (J2000)
43- 44 I2 deg DEd Degree of Declination (J2000)
46- 47 I2 arcmin DEm Arcminute of Declination (J2000)
49- 53 F5.2 arcsec DEs Arcsecond of Declination (J2000)
55- 60 F6.3 mag Bmag [14.176/15.442] B band magnitude
62- 67 F6.3 mag Vmag [13.415/14.867] V band magnitude
69- 74 F6.3 mag Jmag [10.829/13.716] J band magnitude
76- 81 F6.3 mag Hmag [10.271/13.427] H band magnitude
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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 Heliocentric Julian Date of observation
15- 21 F7.5 --- Phase [0.00237/0.99992] Orbital phase
23- 30 F8.5 mag mag [11.99887/16.7399] Magnitude in Band
32- 32 A1 --- Band [BVRI] Passband used (Bessell B, V, R or I)
34- 36 A3 --- Seas [S15/S16] Observational season (2015 or 2016)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 30-Apr-2019