Peremennye Zvezdy

"Peremennye Zvezdy",
Prilozhenie
,
vol. 15, N 9 (2015)

Six Double-Mode Variables

A. V. Khruslov
Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia

Received:   14.08.2013;   accepted:   17.12.2015
(E-mail for contact: khruslov@bk.ru)


#NameOtherCoord (J2000)TypeMaxMinSystemPeriodEpoch (JD)typeSpCommentL.CurveFind.ChartData
1 GSC 3282-0014501 36 23.21, +48 00 28.4RRC13.1213.53WASP(see Comments)(see Comments)max Comm. 11.PNGchart1.PNG1SWASP_data_1.txt
2 GSC 1340-0024606 25 41.61, +22 06 19.5HADS(B)12.2012.65WASP(see Comments)(see Comments)max Comm. 22.PNGchart2.PNGASAS 062542+2206.4 1SWASP_data_2.txt
3 GSC2.3 S8GA12560817 18 24.66, -28 49 52.1CEP(B)16.2916.78Ic(see Comments)(see Comments)max Comm. 33.PNGchart3.PNGOGLE-BLG-RRLYR-00293
4 USNO-B1.0 0611-063621917 57 11.86, -28 51 48.3CEP(B)15.2415.71Ic(see Comments)(see Comments)max Comm. 44.PNGchart4.PNGOGLE-BLG-T2CEP-209
5 GSC 8455-0078123 18 01.14, -45 19 55.0HADS(B)12.7913.74CV(see Comments)(see Comments)max Comm. 55.PNGchart5.PNGASAS 231801-4519.9 1SWASP_data_5.txt SSS_data_5.txt
6 USNO-B1.0 1038-062247923 18 34.55, +13 51 26.2RRC14.4815.02CV(see Comments)(see Comments)max Comm. 66.PNGchart6.PNGCSS_data_6.txt

Comments:


1. The variability of GSC 3282-00145 was discovered in 2013 by Alexandr Ditkovsky (the VS-COMPAS project) from ROTSE-I/NSVS data. The AAVSO Variable Star Index suggests type RRC, with the light elements:
Max = HJD 2451541.127 + 0d.204929 × E.
According to data from 1SWASP (Butters et al. 2010), it is actually an RRC star with a non-radial pulsation co-existing with the first-overtone mode. The light elements are:

ModeFrequency, c/d Semi-amplitude, WASP_mag Period, days Epoch, HJD
f1 4.87971 0.124 0.204930 2454380.119
f2 5.32586 0.030 0.187763 2454380.080

The period ratio is P2 / P1 = 0.9162. J–K = 0.206 (2MASS).

2. The variability of GSC 1340-00246 was discovered by Pojmanski (2002). The ASAS-3 catalog lists the variable as a DSCT star with the elements:
Max = HJD 2452622.986 + 0d.094964 × E.
I re-investigated the star using the currently available ASAS-3 and 1SWASP data. It is actually a HADS(B) star, pulsating in the fundamental and first overtone modes. The light elements are:

ModeFrequency, c/d Semi-amplitude,
WASP mag / V(ASAS) mag
Period, days Epoch, HJD
f1 8.524640 0.089 / 0.114 0.1173070 2454000.099
f0 6.551002 0.066 / 0.093 0.1526484 2454000.133
f1 + f0 15.07563 0.026 / 0.037 0.0663322 2454000.0398
f1 – f0 1.97348 0.015 / – 0.50672 2454000.47
2f1 17.04931 0.008 / – 0.0586534 2454000.0328
2f1 + f0 23.60038 0.006 / – 0.0423722 2454000.0215

The period ratio is P1 / P0 = 0.7685; possibly P2 / P1 = 0.7870 and P2 / P0 = 0.6048. J–K = 0.166 (2MASS). From the ASAS-3 data, the variability range is 12m.12 – 12m.74 in the V band.

3. The variability of OGLE-BLG-RRLYR-00293 was discovered by Soszynski et al. (2011a). The variable was classified as an RRAB variable with the light elements:
Max = HJD 2455000.13654 + 0d.42303636 × E.
I re-analyzed the OGLE-III observations. Actually, this is a double-mode Cepheid (type DCEP(B)) with the elements:

ModeFrequency, c/d Semi-amplitude, IC mag Period, days Epoch, HJD
f0 2.363865 0.1733 0.423036 2452500.419
f1 3.398055 0.0452 0.294286 2452500.303
f1 + f0 5.761909 0.0164 0.1735536 2452500.340

Possible interaction frequencies: f1 + 2f0 (P = 0d.123067); 2f0 (P = 0d.211518). The galactic latitude is b = +5°.046. M–m = 0.33 P (fundamental mode pulsation).

4. The variability of OGLE-BLG-T2CEP-209 was discovered by Soszynski et al. (2011b). The variable was classified as a BL Her variable star with the light elements:
Max = HJD 2455000.14712 + 1d.1812838 × E.
The cited authors give the secondary periods 0d.83298, 0d.48851, 0d.34559. I re-analyzed the OGLE-III observations. Actually, this is a double-mode Cepheid (type DCEP(B)), pulsating in the fundamental and first overtone modes. The presented secondary periods correspond to the first-overtone frequency and interaction frequencies f1 + f0, f1 + 2f0; besides, we detected 8 more frequencies. The light elements are:

ModeFrequency, c/d Semi-amplitude, IC mag Period, days Epoch, HJD
f0 0.846532 0.2080 1.18129 2453600.43
f1 1.200509 0.0224 0.832980 2453600.197
f1 + f0 2.047041 0.0182 0.488510 2453600.180
f1 + 2f0 2.893594 0.0162 0.345591 2453600.240
f1 – f0 0.353950 0.0078 2.82526 2453601.39
f1 + 4f0 4.58665 0.0074 0.218024 2453600.433
4f0 – f1 2.185616 0.0047 0.457537 2453600.220
4f0 3.386238 0.0035 0.295313 2453600.301
3f0 – f1 1.33912 0.0035 0.74676 2453600.11
2f0 – f1 0.492577 0.0034 2.03014 2453601.83
5f0 + f1 5.43319 0.0030 0.184054 2453600.240
5f0 4.23268 0.0025 0.236257 2453600.301

Analyzing the OGLE data, we rejected observations of JD 2454221 that give a too large scatter of the light curve. The galactic latitude is b = –2°.142.

5. The variability of GSC 8455-00781 was discovered by Pojmanski (2002). The ASAS-3 catalog lists the variable as a DSCT star with the elements:
Max = HJD 2451869.763 + 0d.11501 × E.
I re-investigated the star using the currently available ASAS-3, 1SWASP, and SSS data. It is actually a high-amplitude double-mode Delta Scuti star. The light elements are:

ModeFrequency, c/d Semi-amplitude,
WASP mag / V(SSS) mag / V(ASAS) mag
Period, days Epoch, HJD
f0 8.694858 0.249 / 0.225 / 0.231 0.1150105 2454200.102
f1 11.24637 0.075 / 0.061 / 0.077 0.0889176 2454200.071
f1 + f0 19.94121 0.047 / 0.042 / 0.049 0.0501474 2454200.0295
f1 – f0 2.551470 0.038 / 0.035 / – 0.391931 2454200.345
2f0 + f1 28.63606 0.025 / 0.023 / – 0.0349210 2454200.0145
2f0 – f1 6.143336 0.013 / 0.020 / – 0.162778 2454200.145
3f0 – f1 14.83829 0.007 / – / – 0.0673932 2454200.0465
f0 + 2f1 31.18753 0.011 / – / – 0.0320641 2454200.0065
3f0 + f1 37.33098 0.008 / – / – 0.0267874 2454200.0060
4f0 – f1 23.53312 0.006 / – / – 0.0424933 2454200.0213
2f0 17.38967 0.003 / – / – 0.0575054 2454200.0550
3f0 26.08433 0.002 / – / – 0.0383372 2454200.0225

The period ratio of the first-overtone and fundamental modes is P1 / P0 = 0.7731. J–K = 0.156 (2MASS). From the ASAS-3 data, the variability range is 12m.9 – 13m.7 in the V band; from the 1SWASP data, 13m.00 – 13m.91.

6. The variability of USNO-B1.0 1038-0622479 was discovered by Drake et al. (2014; the Catalina surveys periodic variable star catalog). The variable was classified as an RRC star with the period 0d.258489. I re-analyzed the CSS observations, with the RR Lyrae nature and period of the variable confirmed. A secondary (non-radial) wave is superimposed on the first overtone pulsation. The non-radial period is constant in all time interval of CSS data, the first overtone period varies. The light elements:
First-overtone period (P1):
JD 2453500 – 2454500: HJD = 2454000.062 + 0d.258493 ×E;
JD 2454600 – 2455600: HJD = 2455000.175 + 0d.258477 ×E;
JD 2455600 – 2456600: HJD = 2456000.185 + 0d.258464 ×E.
Non-radial pulsation (P2):
JD 2453500 – 2456600: HJD = 2455000.222 + 0d.260058 ×E.
The amplitudes of the two oscillations vary:

JDSemi-amplitude, V mag
A1 / A2
2453500–2454500 0.133 / 0.078
2454600–2455600 0.159 / 0.057
2455600–2456600 0.177 / 0.048

The period ratio is P1 / P2 = 0.9939 – 0.9940. J–K = 0.095 (2MASS); B–V = 0.321 (APASS).

Remarks:
I present a new investigation of six known variable stars. I analyzed all observations available for these stars in the ASAS-3 (Pojmanski 2002), SuperWASP (Butters et al. 2010), OGLE-III, 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-mode variables, pulsating in the radial (type HADS(B) and CEP(B)) or radial and non-radial (type RRC) modes.

The period ratios P1 / P0 for stars Nos. 2 and 5 are typical for radially pulsating high-amplitude double-mode Delta Scuti stars (Petersen and Christensen-Dalsgaard 1996). The period ratios P1 / P0 for stars Nos. 3 and 4 (Cepheids) are also similar.

Along with the light curves, I present power spectra of the variables, for the raw data and after subtraction of the first-overtone (or fundamental mode) oscillations. The structure of the power spectra shows that the secondary periods are real. In certain cases, frequencies related to interactions between the two main modes were found (see the Comments).

The tabulated coordinates of the variables were drawn from the 2MASS, GSC2.3, and USNO-B1.0 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: The author wishes 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. Astrophys., 520, L10
Drake, A.J., Djorgovski, S.G., Mahabal, A., et al., 2009, Astrophys. J., 696, 870
Drake, A.J., Graham, M.J., Djorgovski, S.G., et al., 2014, Astrophys. J. Suppl., 213, 9
Petersen, J.O., Christensen-Dalsgaard, J., 1996, Astron. Astrophys., 312, 463
Pojmanski, G., 2002, Acta Astronomica, 52, 397
Sokolovsky, K.V., 2007, Perem. Zvezdy Prilozh., 7, No. 30
Soszynski, I., Dziembowski, W.A., Udalski, A., et al., 2011a, Acta Astron., 61, 1
Soszynski, I., Udalski, A., Pietrukowicz, P., et al., 2011b, Acta Astronomica, 61, 285



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