Comments:
1. The variability of GSC 2420-00093 was discovered by Přibik & Brat (2009).
The variable was classified as a HADS(B) variable, pulsating in the fundamental
and first overtone modes
with one additional frequency. Přibik & Brat give the following light elements:
HJD(max) 2454758.4180 + 0.07105196×E (fundamental mode period);
HJD(max) 2454758.4072 + 0.05503008×E (first overtone period);
HJD(max) 2454758.4170 + 0.04250400×E (additional period).
I re-analyzed 1SWASP data and confirm the HADS(B) nature of this variable
as well as two of the three periods (the fundamental and first-overtone ones).
It is actually a triple-mode HADS(B) star, pulsating in the fundamental, first, and
second overtone modes. The additional period suggested by Přibik & Brat
(2009) is a one-day alias
of
the real second overtone period
(see the Table).
Ñonfidently identified are also frequencies related to
interactions
between the three main modes:
f1 – f0, f2 – f0,
f1 + f0, f2 + f0.
The light elements are:
| Mode |
Frequency, c/d |
Semi-amplitude, WASP mag |
Period, days |
Epoch, HJD |
| f0 |
14.07349 |
0.079 |
0.0710556 |
2454100.533 |
| f1 |
18.17151 |
0.027 |
0.0550312 |
2454100.525 |
| f2 |
22.52663 |
0.016 |
0.0443919 |
2454100.5395 |
| f1 – f0 |
4.09803 |
0.009 |
0.24402(0) |
2454100.523 |
| f2 – f0 |
8.45316 |
0.005 |
0.118299 |
2454100.576 |
| f1 + f0 |
32.24496 |
0.005 |
0.0310126 |
2454100.5255 |
| f2 + f0 |
36.6001 |
0.004 |
0.0273223 |
2454100.508 |
P1/P0 = 0.7745, P2/P1 = 0.8067. B–V
= 0.010 (Tycho2), J–K = 0.248 (2MASS).
In our Galaxy, this is the fourth case of a triple-mode HADS(B) star, along
with the previosly known DO CMi (Wils et al. 2008),
V829 Aql (Handler et al. 1998), and the newly discovered TYC 3144-595-1 (Ulusoy
et al. 2013).
2. The variability of TYC 7805 00075 1 was discovered by Pojmanski (2002).
The ASAS-3 catalog lists the variable as a DSCT star with the elements HJD(max) 2451903.31
+ 0.166993×E.
I reinvestigated the star using the currently available 1SWASP and ASAS-3 data.
I confirm the delta Scuti nature and the fundamental period of this variable.
A secondary wave (possibly nonradial) is superimposed on the fundamental pulsation.
The light elements are:
| Mode |
Frequency, c/d |
Semi-amplitude, mag |
Period, days |
Epoch, HJD |
| f1 |
5.988124 |
0.081 (WASP), 0.078 (V, ASAS) |
0.1669972 |
2455200.003 |
| f2 |
9.69979 |
0.007 (WASP), 0.007 (V, ASAS) |
0.103095 |
2455200.067 |
The period ratio is: P2/P1 = 0.6173.
f2 is possibly a nonradial pulsation; its identification with the second
overtone
mode is not excluded.
Also not excluded are other weak pulsations, with the periods of 0.0997346
days, 0.1822313
days, 0.0995966 days and small amplitudes.
B–V = 0.411 (Tycho2), J–K = 0.174 (2MASS). From the ASAS-3 data,
the variability range is 9m.66
– 9m.89 (V).
The WASP data from different time intervals exhibit considerable
differences of the mean brightness; my analysis was based on one of them,
JD2454148–2454274.
3. The variability of TYC 8699 00544 1 was discovered by Pojmanski (2002).
The ASAS-3 catalog lists the variable as a DSCT star with the elements HJD(max) 2451920.154
+ 0.126749×E.
I reinvestigated the star using the currently available ASAS-3 data.
It is actually a high-amplitude double-mode Delta Scuti star.
The light elements are:
| Mode |
Frequency, c/d |
Semi-amplitude, V mag |
Period, days |
Epoch, HJD |
| f0 |
7.889752 |
0.107 |
0.1267467 |
2453600.5683 |
| f1 |
10.238370 |
0.030 |
0.0976718 |
2453600.577 |
The period ratio of the first overtone and fundamental modes is
P1 / P0 = 0.7706.
B–V = 0.397 (Tycho2), J–K = 0.224 (2MASS).
4. The variability of GSC 3881-00874 was reported in 2012 by P. Wils in the VSX
database
(BPS BS 16084-151) according to 1SWASP data (Butters
et al. 2010).
The star was classified by the discoverer as a DSCT star with the
light elements:
HJD(max) 2454286.400 + 0.061144×E.
I reinvestigated the star using the currently available 1SWASP data.
It is actually a high-amplitude double-mode Delta Scuti star.
The light elements are:
| Mode |
Frequency, c/d |
Semi-amplitude, WASP mag |
Period, days |
Epoch, HJD |
| f0 |
16.355196 |
0.072 |
0.06114265 |
2454450.5110 |
| f1 |
21.05112 |
0.020 |
0.0475034 |
2454450.5245 |
| f1 + f0 |
37.40625 |
0.006 |
0.0267335 |
2454450.5172 |
| fN |
16.46578 |
0.005 |
0.0607320 |
2454450.5493 |
The period ratio of the first overtone and fundamental modes is
P1 / P0 = 0.7769.
J–K = 0.156 (2MASS).
From the CSS data, the variability range is 13m.09 – 13m.25
(CV).
5. The delta Scuti nature of NSV 09856 = HV 10309 was reported by Kazarovets & Pastukhova
(2013) according to ASAS-3 data.
Their light elements are: HJD(max) 2453581.7052 + 0.1184880×E.
I re-analyzed the ASAS-3 data. It is actually a triple-mode HADS(B) star, pulsating
in the fundamental,
first-overtone, and second-overtone modes.
In our Galaxy, it is the fifth case of a triple-mode HADS(B) star.
The light elements are:
| Mode |
Frequency, c/d |
Semi-amplitude, V mag |
Period, days |
Epoch, HJD |
| f0 |
8.439673 |
0.090 |
0.1184880 |
2453581.7052 |
| f1 |
10.95611 |
0.066 |
0.0912733 |
2453581.7065 |
| f2 |
13.65426 |
0.027 |
0.0732372 |
2453581.7080 |
| f1 – f0 |
2.516521 |
0.024 |
0.397374 |
2453581.715 |
| f1 + f0 |
19.39582 |
0.018 |
0.0515575 |
2453581.7497 |
P1 / f0 = 0.7703;
P2 / f1 = 0.8024;
P2 / f0 = 0.6181.
J–K = 0.239 (2MASS).
6. The variability of GSC 6905-01641 was reported by Keller et al. (2008, SEKBO 112944.737).
The variable was classified as a possible RR Lyrae star (RR:) without light
elements.
According to the Siding Springs Survey data (Drake et al. 2009), it is a double-mode
HADS star. The
light elements are:
| Mode |
Frequency, c/d |
Semi-amplitude, ÑV mag |
Period, days |
Epoch, HJD |
| f0 |
14.53469 |
0.147 |
0.0688009 |
2455000.5337 |
| f1 |
18.76433 |
0.039 |
0.0532926 |
2455000.5470 |
The period ratio is P1 / P0 = 0.7746. J–K = 0.121 (2MASS).
7. The variability of TYC 2706 01244 1 was reported in 2011 by Gregor Srdoc
in the VSX database (VSX J211253.6+331734),
according to 1SWASP data (Butters et al. 2010).
The star was classified by the discoverer as a HADS star with the light elements:
HJD(max) 2454318.4732 + 0.08785×E.
I re-analyzed 1SWASP and NSVS data and found out that the variable
was actually a double-mode HADS star.
The light elements are:
| Mode |
Frequency, c/d |
Semi-amplitude, mag |
Period, days |
Epoch, HJD |
| f2 |
11.38334 |
0.060 (WASP), 0.052 (R, NSVS) |
0.0878477 |
2454340.557 |
| f1 |
9.49652 |
0.040 (WASP), 0.044 (R, NSVS) |
0.105302 |
2454340.558 |
| f2 + f1 |
20.8798 |
0.009 (WASP) |
0.0478932 |
2454340.5460 |
| f2 – f1 |
1.8882 |
0.004 (WASP) |
0.5296 |
2454340.53 |
| 2f2 + f1 |
32.2630 |
0.004 (WASP) |
0.0309953 |
2454340.5152 |
| f2 + 2f1 |
30.3759 |
0.002 (WASP) |
0.0329208 |
2454340.5115 |
The period ratio is P2 / P1 = 0.8342.
Radial pulsations in the second and third overtones are not excluded.
B–V = 0.402 (Tycho2), J–K = 0.210 (2MASS).
Remarks:
I present an investigation of seven high-amplitude Delta Scuti variables.
I re-analysed all observations available for these stars from the
SuperWASP (Butters et al. 2010),
ASAS-3 (Pojmanski 2002),
ROTSE-I/NSVS (Woźniak et
al. 2004) and
Catalina
Surveys (Drake et al. 2009)
online public archives
using the period-search software developed by Dr. V.P. Goranskij for Windows
environment.
According to these data, the variables are double- or multimode high-amplitude
Delta
Scuti stars.
The period ratios P1/P0 and P2/P1
are
typical for radially pulsating high-amplitude
double-mode and multi-mode Delta Scuti stars
(Petersen & Christensen-Dalsgaard 1996). In one case, we possibly encounter
nonradial
pulsations
(or F and 2O modes), and one case
possibly corresponds to pulsations in the second and third overtone modes.
In certain cases, multiple frequencies or frequencies related to
interactions
between the two main modes were found (see the Comments).
The coordinates were drawn either from the Tycho-2 or from the 2MASS catalogs.
The SuperWASP observations are available as FITS tables, which were converted
into ASCII tables using the OMC2ASCII program as
described by Sokolovsky (2007).
Acknowledgements: I am grateful to Dr. K.V. Sokolovsky for his advice concerning
data retrieving. I wish
to thank Dr. V.P. Goranskij for providing his software. This study was supported
by the Russian Foundation for Basic
Research (grant 13-02-00664) and by the Programme "Non-stationary Phenomena of
Objects
in the Universe" of the
Presidium of Russian Academy of Sciences.
References:
Butters, O.W., West, R.G., Anderson, D.R., et al., 2010, Astron. and Astrophys.,
520, L10
Drake, A.J., Djorgovski, S.G., Mahabal, A., et al., 2009, Astrophys. J., 696,
870
Handler, G., Pikall, H. and Diethelm, R., 1998, Inform. Bull. Var. Stars, No.
4549
Kazarovets, E.V., Pastukhova, E.N., 2013, Perem. Zvezdy Prilozh., 13, No. 20
Keller, S.C., Murphy, S., Prior, S., et al., 2008, Astrophys. J., 678, 851
Petersen, J.O., Christensen-Dalsgaard, J., 1996, Astron. and Astrophys., 312,
463
Pojmanski, G., 2002, Acta Astronomica, 52, 397
Přibik, V. , Brat, L., 2009, Open European Journal on Variable Stars, 109,
4
Sokolovsky, K.V., 2007, Perem. Zvezdy Prilozh., 7, No. 30
Ulusoy, C., Ulaş, B., Gülmez, T., et al., 2013, Monthly Not. Roy.
Astron.
Soc., 433,
394
Wils, P., Rozakis, I., Kleidis, S., et al., 2008, Astron. and Astrophys., 478,
865
Woźniak, P.R., Vestrand, W.T., Akerlof, C.W., et al., 2004, Astron. J.,
127,
2436
