J/AJ/162/149 Pulsational changes in classical cepheid X Cygni (Hintz+, 2021)
An examination of pulsational changes in the classical cepheid X Cygni.
Hintz E.G., Harding T.B., Hintz M.L.
<Astron. J., 162, 149-149 (2021)>
=2021AJ....162..149H 2021AJ....162..149H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable; Spectra, optical; Radial velocities
Keywords: Cepheid variable stars; Radial velocity; Variable star period change
Abstract:
Using an extensive archive for visual observations from the AAVSO,
along with published times of maximum light, we determined a new model
for the period of X Cygni. The best model is two linear fits for data
before and after 1917 (JD2421512). Before that time the period is
16.38438±0.00036days. After we find a period of
16.386470±0.000028days. An examination of the O-C values for data
after 1917 shows no clear evidence of a constant period change or of
sinusoidal variations. The period looks to be constant. From an
examination of H-alpha index measurements we find a drop in the value
between data before 2013 October and data after 2014 July. This drop
is not related to temperature and is likely related to mass loss in
the star. Finally, we find that radial-velocity measurements match
well with previously published values and show no seasonal variation
over the 11yr of data. This again seems to limit the possibility of a
companion.
Description:
A total of 344 spectrum of X Cyg were obtained from 2010 June until
2020 October, using the 1.2m McKellar Telescope of the Dominion
Astrophysical Observatory (DAO). The Coude spectrograph with the 3231
grating was used along with the Site4 CCD. This provided coverage from
about 4450-6970Å over 4096pixels.
Objects:
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RA (2000) DE Designation(s) (Period)
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20 43 24.19 +35 35 16.1 X Cygni = V* X Cyg (P=16.38438d)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 31 333 Hα, Hβ, and radial velocity values
for X Cygni
table2.dat 28 102 *Times of Maximum Light for X Cygni
table3.dat 38 345 New times of maximum light for X Cygni
fig4.dat 14 4083 Continuum calibrated spectra of X Cygni
fig6.dat 19 84 O-C diagram around time of Hα shift
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Note on table2.dat : From Szabados, 1991CoKon..96..123S 1991CoKon..96..123S.
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See also:
J/AJ/144/92 : Times of maximum light for the SX Phe star XX Cyg (Yang+, 2012)
J/AJ/150/204 : Spectroscopy of standard stars (Joner+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d HJD [2455366/2459129] Heliocentric Julian Day
15- 19 F5.3 mag Halpha [2.62/2.73] Hα index
21- 25 F5.3 mag Hbeta [2.6/2.69]? Hβ index
27- 31 F5.1 km/s RVel [-22.3/31.6] Radial velocity
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d HJD [2410255/2442373] Heliocentric Julian Day
13- 17 I5 --- Cycle [-2049/-89] Cycle number of maximum
19- 21 A3 --- Type Type of Observations
23- 28 F6.3 d OC [-0.65/2.21] Observed minus Calculated Time Maximum
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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- 11 F11.3 d HJD [2443011/2459168] Heliocentric Julian Day
13- 15 I3 --- Cycle [-50/936] Cycle number of maximum
17- 19 A3 --- Type Type of Observations
21- 26 F6.3 d OC [-1.28/0.89] Observed minus Calculated Time of Maximum
28- 38 A11 --- Ref Source of Time of Maximum light (1)
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Note (1): References as follows:
Bendnikov = Bendnikov, 1992SvAL...18..130B 1992SvAL...18..130B
Current = This work.
Kiss 1998 = Kiss, 1998MNRAS.297..825K 1998MNRAS.297..825K
Speil 1985 = Speil, 1985JAVSO..14...18S 1985JAVSO..14...18S
Turner 1999 = Turner, 1999JAVSO..27....5T 1999JAVSO..27....5T
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Byte-by-byte Description of file: fig4.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 0.1nm Wave [4496/6939] Wavelength; Angstroms
10- 14 F5.3 --- I [0.29/1.25] Relative Intensity
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Byte-by-byte Description of file: fig6.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d HJD [2445731/2459123] Heliocentric Julian Day
14- 19 F6.3 d OC [-0.41/0.41] Observed-Calculated
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 15-Dec-2021