Comments:
1.
The variability of GSC 4064-00179 = NSVS 2030690 = NSVS 2058214
was discovered by Khruslov (2005)
from ROTSE-I/NSVS data (Wozniak et al. 2004; also see http://skydot.lanl.gov/nsvs).
The variable was classified as a CWB Cepheid with the period of 1.1136 d.
This variability type was chosen because of the variable's position at a
distance from the galactic plane (b = +7.4 deg) somewhat larger than typical of
classical Cepheids and a period somewhat too short. At that time, I analyzed
only the ROTSE data without photometric correction flags (higher precision data).
Now I performed a repeated analysis of the NSVS data, also retaining those with
photometric correction flags and thus considerably increasing the number of data
points. In this analysis, I rejected all observations with uncertainties in
excess of 0.15 mag (plotted as small dots). As a result, I was able to reveal
two periodicities of the star, characteristic of double-mode
Cepheids.
| Mode |
Frequency, c/d |
Semi-amplitude, Rmag |
Period, days |
Epoch, HJD |
| f1 |
0.8982 |
0.172 |
1.1133 |
2451497.64 |
| f2 |
1.1181 |
0.046 |
0.8944 |
2451498.18 |
The period ratio P2/P1 = 0.8034 is typical of beat Cepheids pulsating in the first
and second overtone modes.
J-H = 0.493 (2MASS).
2.
The variability of TYC 5992 02251 1 = ASAS 074343-2050.3 was
reported by
Pojmanski (2002). ASAS 074343-2050.3, listed in the ASAS catalog of variable stars
as a first-overtone Cepheid (period 0.73629 d),
is actually a double-mode Cepheid.
| Mode |
Frequency, c/d |
Semi-amplitude, V mag |
Period, days |
Epoch, HJD |
| f1 |
1.358192 |
0.041 |
0.736273 |
2453455.43 |
| f2 |
1.685727 |
0.010 |
0.593216 |
2453455.40 |
| f1+f2 |
3.04395 |
0.005 |
0.328521 |
2453455.40 |
The period ratio P2/P1 = 0.8057 is typical of beat Cepheids pulsating
in the first and second overtone modes.
B-V = 1.233 (Tycho2).
TYC 5992 02251 1 is a close visual double star 2MASS 07434278-2050155 (J=9.437,
J-H = 0.259) and
2MASS 07434249-2050204 (J=8.234, J-H = 0.443), and thus the tabulated
amplitude is too low. The brighter of the stars probably varies, its J-H
color index is more typical of Cepheids.
3.
The variability of NSV 6647 = TYC 8690 02031 1 = ASAS 142346-5829.4
was
reported by Strohmeier et al. (1964).
The star, listed in the ASAS catalog of variable stars as an RRAB variable
(period 0.631294 d), is actually a double-mode Cepheid.
| Mode |
Frequency, c/d |
Semi-amplitude, V mag |
Period, days |
Epoch, HJD |
| f1 |
1.584103 |
0.190 |
0.631272 |
2453556.358 |
| f2 |
1.972822 |
0.029 |
0.506888 |
2453556.358 |
The period ratio P2/P1 = 0.8030 is typical of beat Cepheids
pulsating
in the first and second overtone modes.
B-V = 0.848 (Tycho2), J-H = 0.351 (2MASS).
Remarks:
I present a new investigation of three known pulsating variables.
I re-analysed the ASAS-3 and ROTSE-I/NSVS data (Wozniak et al. 2004) using the period-search
software developed
by Dr. V.P. Goranskij for Windows environment.
According to the data, the stars are double-mode Cepheids, pulsating in the first
and second overtone modes.
The period ratios, P2/P1, are typical of double-mode variables pulsating in the first
and second overtone modes.
The
tabulated coordinates of the variables
were drawn from the Tycho2 and 2MASS catalogs.
References:
Khruslov, A.V., 2005, PZP, 5, No. 3
Pojmanski, G., 2002, Acta Astronomica, 52, 397
Strohmeier, W., Knigge, R., Ott, H., 1964, IBVS, No. 74
Wozniak, P.R., Vestrand, W.T., Akerlof, C.W., et al., 2004, Astron. J., 127, 2436
