J/MNRAS/381/602 BV differential light curves of EQ Tau (Yuan+, 2007)
Variation of the period and light curves of the solar-type contact binary
EQ Tauri.
Yuan J., Qian S.
<Mon. Not. R. Astron. Soc., 381, 602-610 (2007)>
=2007MNRAS.381..602Y 2007MNRAS.381..602Y
ADC_Keywords: Binaries, eclipsing ; Photometry, UBV
Keywords: binaries: close - stars: evolution - stars: individual: EQ Tauri -
stars: magnetic fields - stars: spots
Abstract:
We present two new sets of complete light curves of EQ Tauri (EQ Tau)
observed in 2000 October and 2004 December. These were analysed,
together with the light curves obtained by Yang & Liu
(2002AJ....124.3358Y 2002AJ....124.3358Y) in 2001 December, with the 2003 version of the
Wilson-Devinney code. In the three observing seasons, the light curves
show a noticeable variation in the time-scale of years. The more
massive component of EQ Tau is a solar-type star (G2) with a very deep
convective envelope, which rotates about 80 times as fast as the Sun.
Therefore, the change can be explained by dark-spot activity on the
common convective envelope. The assumed unperturbed part of the light
curve and the radial velocities published by Rucinski et al.
(2001AJ....122.1974R 2001AJ....122.1974R) were used to determine the basic parameters of
the system, which were kept fixed for spot modelling in the three sets
of light curves. The results reveal that the total spotted area on the
more massive component covers 18, 3 and 20 per cent of the
photospheric surface in the three observing seasons, respectively.
Polar spots and high-latitude spots are found. The analysis of the
orbital period has demonstrated that it undergoes cyclical
oscillation, which is due to either a tertiary component or periodic
magnetic activity in the more massive component.
Description:
Our photometric observations of EQ Tau in the B and V bands were
carried out on 2000 October 30 and 31 and 2004 December 11, 12, 18 and
21, with the PI1024 TKB CCD photometric system attached to the 100-cm
reflecting telescope at the Yunnan Observatory, China. The effective
passbands we used are close to the standard UBV photometric system.
Objects:
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RA (2000) DE Designation(s)
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03 48 13.4 +22 18 51 EQ Tau = V* EQ Tau
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 18 257 CCD photometric data of EQ Tau in the B band
observed on 2000 October 30 and 31, and
2004 December 11, 12 and 18
table2.dat 18 296 CCD photometric data of EQ Tau in the V band
observed on 2000 October 30 and 31, and
2004 December 11, 12, 18, and 21
table4.dat 50 109 Time of light minimum for EQ Tauri
refs.dat 114 35 References
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See also:
J/AJ/132/960 : V(RI)c light-curves of EQ Tauri (Hrivnak+, 2006)
Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d JD Julian date
14- 18 F5.3 mag Dmag Differential magnitude in B or V band
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d HJD Heliocentric Julian date
14 A1 --- n_HJD [a] Partial coverage (1)
16- 17 A2 --- Min [I II] First (I) or second (II) minimum
19- 21 A3 --- Method Method used (pg, pe, sp or CCD)
23- 30 F8.1 d E Ephemeris
33- 39 F7.4 --- O-C O-C value
41- 47 F7.4 --- Res Residuals
49- 50 I2 --- Ref References, in refs.dat file
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Note (1): a = The times of minimum observed by Magalashvili & Kumsishvili
(1971, Abastumanskaia Astrofiz. Obs. Bull., 40, 2), which were
sometimes based on partial coverage of the light minimum.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 42 A19 --- Aut Author's name
44-114 A71 --- Com Comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Sep-2008