J/AJ/144/92 Times of maximum light for the SX Phe star XX Cyg (Yang+, 2012)
Stellar pulsations and period changes in the SX Phoenicis star XX Cygni.
Yang X.H., Fu J.N., Zha Q.
<Astron. J., 144, 92 (2012)>
=2012AJ....144...92Y 2012AJ....144...92Y
ADC_Keywords: Stars, variable ; Photometry, CCD
Keywords: stars: individual (XX Cyg) - stars: variables: delta Scuti -
techniques: photometric
Abstract:
Time-series photometric observations were made for the SX Phoenicis
star XX Cyg between 2007 and 2011 at the Xinglong Station of National
Astronomical Observatories of China. With the light curves derived
from the new observations, we do not detect any secondary maximum in
the descending portion of the light curves of XX Cyg, as reported in
some previous work. Frequency analysis of the light curves confirms a
fundamental frequency f0=7.4148cycles/day and up to 19 harmonics, 11
of which are newly detected. However, no secondary mode of pulsation
is detected from the light curves. The O-C diagram, produced from 46
newly determined times of maximum light combined with those derived
from the literature, reveals a continuous period increase with the
rate of (1/P)(dP/dt)=1.19(13)x10-8/yr. Theoretical rates of period
change due to the stellar evolution were calculated with a modeling
code. The result shows that the observed rate of period change is
fully consistent with period change caused by evolutionary behavior
predicted by standard theoretical models.
Description:
New photometric observations for XX Cyg were mainly made with the 85cm
telescope located at the Xinglong Station of National Astronomical
Observatories of China (NAOC) between 2007 and 2011. The 85cm
telescope is equipped with a standard Johnson-Cousin-Bessel multicolor
filter system and a PI1024 BFT CCD camera. The observations were made
through a standard Johnson V filter. Observations were also made with
the 60cm telescope at Yunnan Astronomical Observatory (YAO) in China,
which is equipped with an Andor's DW436 2048*2048 CCD camera. In
total, more than 130hr of data were collected over 29 nights. Newly
determined times of maximum light are combined with those available in
literature.
Objects:
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RA (2000) DE Designation(s) (Period)
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20 03 15.65 +58 57 16.5 XX Cyg = HIP 98737 (P=0.1349)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 37 288 Times of maximum light and O-C values of XX Cyg
refs.dat 78 29 Reference
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See also:
J/PASP/125/639 : Time of Maxima for the Sx Phe star BL Cam (Conidis+, 2013)
J/MNRAS/419/342 : SX Phe stars in globular clusters (Cohen+, 2012)
J/PASP/123/26 : Time of Maxima for the SX Phe star XX Cyg (Conidis+ 2011)
J/AJ/139/2639 : DY Peg times of light maximum (Li+, 2010)
J/AJ/135/1958 : KZ Hya times of maximum light (Fu+, 2008)
J/AZh/84/695 : An SX Phoenicis Variable light curve (Kim+, 2007)
J/other/IBVS/5731 : Minima and maxima of 816 variables (Hubscher+, 2006)
J/A+A/359/597 : Photometry of SX Phe stars in globular clusters
(Rodriguez+, 2000)
J/A+AS/100/571 : uvby-beta photometry of SX Phe stars (Rodriguez+ 1993)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Running sequence number
5- 15 F11.5 d Tmax Observed times light maxima; HJD-2400000
17- 23 I7 --- E Cycle number
25- 32 F8.5 d O-C The O-C value
34- 35 I2 --- Ref Data source; in refs.dat file
37 A1 --- f_Ref [*] * = point not used in O-C because of large
discrepancies with the rest of the data)
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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 Bibliographic code
24- 44 A21 --- Aut Author's name
46- 78 A33 --- Com Comments
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History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 17-Oct-2013