Peremennye Zvezdy

"Peremennye Zvezdy",
Prilozhenie
,
vol. 14, N 2 (2014)

Seven Double-Mode RR Lyrae Variables

S. Huemmerich#1,2, A. V. Khruslov#3
#1. Bundesdeutsche Arbeitsgemeinschaft fuer Veraenderliche Sterne e.V. (BAV), Berlin, Germany;
#2. Braubach, Germany;
#3. Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia.

Received:   11.06.2013;   accepted:   15.01.2014
(E-mail for contact: ernham@rz-online.de , khruslov@bk.ru)


#NameOtherCoord (J2000)TypeMaxMinSystemPeriodEpoch (JD)typeSpCommentL.CurveFind.ChartData
1 GSC 0839-0017010 43 06.16, +09 03 40.4RR(B)13.3914.07CV(see Comments)(see Comments)max Comm. 11.PNGchart1.PNGCSS_MLS_data_1.txt ASAS 104306+0903.7 NSVS 10303225
2 USNO-A2.0 0900-0681351710 57 31.42, +04 57 03.7RR(B)13.3914.05CV(see Comments)(see Comments)max Comm. 22.PNGchart2.PNGCSS_MLS_data_2.txt ASAS 105731+0457.0 NSVS 13082928
3 USNO-A2.0 0750-0806939813 13 42.53, -10 13 55.8RR(B)16.4217.37CV(see Comments)(see Comments)max Comm. 33.PNGchart3.PNGCSS_MLS_data_3.txt
4V1360 CenGSC 7304-0011914 39 29.75, -33 51 27.2RR(B)13.0813.75CV(see Comments)(see Comments)max Comm. 44.PNGchart4.PNGSSS_data_4.txt 1SWASP_data_4.txt ASAS 143930-3351.4
5 GSC 0925-0050315 07 40.60, +12 41 42.9RR(B)13.2613.83CV(see Comments)(see Comments)max Comm. 55.PNGchart5.PNGCSS_data_5.txt ASAS 150741+1241.6 NSVS 10564788
6 USNO-A2.0 0675-1479516215 51 56.61, -18 03 19.2RR(B)16.2017.12CV(see Comments)(see Comments)max Comm. 66.PNGchart6.PNGCSS_MLS_SSS_data_6.txt
7 USNO-A2.0 0975-2024059721 19 27.06, +11 05 56.7RR(B)15.6516.25CV(see Comments)(see Comments)max Comm. 77.PNGchart7.PNGCSS_data_7.txt

Comments:


1. According to VSX, variability of GSC 0839-00170 was reported in 2013 by Alexandr Ditkovsky (VS-COMPAS project), based on ROTSE-I/NSVS data. VSX suggests type RRC with Blazhko effect, the listed light elements are: HJD(max) = 2453362.802 + 0.417517×E. Based on the data from ROTSE-I/NSVS, ASAS-3 and Catalina Surveys, it is actually a double-mode RR Lyrae star, type RR(B), with the light elements tabulated below.

ModeFrequency, c/d Semi-amplitude, mag Period, days Epoch, JD
f1 2.395101 0.150 (CV, CSS, MLS), 0.172 (V, ASAS), 0.097 (R, NSVS) 0.417519 2455000.747
f0 1.785472 0.080 (CV, CSS, MLS), 0.081 (V, ASAS), 0.061 (R, NSVS) 0.560076 2455000.521
f1 + f0 4.180515 0.040 (CV, CSS, MLS) 0.239205 2455000.638
f1 – f0 0.609611 0.021 (CV, CSS, MLS) 1.64039 2455001.24

The period ratio of the first-overtone and fundamental modes is P1/P0 = 0.7455. J–K = 0.234 (2MASS), B–V = 0.344 (APASS). Combined brightness of two stars, GSC 0839-00170 (= var) and GSC 0839-00205, was measured in NSVS, the amplitudes are somewhat underestimated.

2. Variability of USNO-A2.0 0900-06813517 was discovered by Alexandr Ditkovsky from VS-COMPAS project in 2012, based on ROTSE-I/NSVS data. The AAVSO Variable Star Index suggests type RRC with Blazhko effect, the listed light elements are: HJD(max) = 2452732.721 + 0.348758×E. Based on data from Catalina Surveys, it is actually a double-mode RR Lyrae star, type RR(B), with the light elements tabulated below.

ModeFrequency, c/d Semi-amplitude, CV mag Period, days Epoch, JD
f1 2.867342 0.169 0.348755 2455000.680
f0 2.130992 0.092 0.469265 2455000.701
f1 + f0 4.998276 0.037 0.200069 2455000.673

The period ratio of the first-overtone and fundamental modes is P1/P0 = 0.7432. J–K = 0.238 (2MASS), B–V = 0.265 (APASS). The ROTSE data with photometric correction flags were kept for the analysis.

3. The variability of USNO-A2.0 0750-08069398 was reported by Keller et al. (2008; Id. 109253.24). The variable was classified as an RR: star without light elements. Based on Catalina Surveys data, it is actually a double-mode RR Lyrae star, type RR(B), with the light elements tabulated below.

ModeFrequency, c/d Semi-amplitude, CV mag Period, days Epoch, JD
f1 2.866159 0.144 0.348899 2454800.775
f0 2.130456 0.121 0.469383 2454800.730

The period ratio of the first-overtone and fundamental modes is P1/P0 = 0.7433. J–H = 0.280 (2MASS).

4. The variability of V1360 Cen was discovered by Hoffmeister (1963). The variable is listed in the GCVS (Samus et al. 2007–2013) as an RR Lyrae star, type RRC, with the light elements: JD(max) = 2452498.53 + 0.344249×E. Based data from 1SWASP, ASAS-3 and Catalina Surveys, it is actually a double-mode RR Lyrae star, type RR(B), with the light elements tabulated below.

ModeFrequency, c/d Semi-amplitude, mag Period, days Epoch, JD
f1 2.904798 0.164 (CV, SSS), 0.200 (WASP), 0.194 (V, ASAS) 0.344258 2454200.540
f0 2.159491 0.100 (CV, SSS), 0.132 (WASP), 0.115 (V, ASAS) 0.463072 2454200.806
f1 + f0 5.06429 0.045 (CV, SSS), 0.055 (WASP), 0.048 (V, ASAS) 0.197461 2454200.623
f1 – f0 0.745323 0.028 (CV, SSS), 0.031 (WASP) 1.34170 2454200.90
2f1 + f0 7.96902 0.019 (WASP) 0.125486 2454200.579

The period ratio of the first-overtone and fundamental modes is P1/P0 = 0.7434. J–K = 0.200 (2MASS); B–V = 0.355 (APASS). When plotting the phased light curves for the identified frequencies, f1 and f0, we also subtracted variations of the mean brightness in the 1SWASP data, probably of instrumental origin (corresponding to the frequency f = 1 in the power spectra). All the observations from the SuperWASP with the error > 0.m05 were rejected.

5. Variability of GSC 0925-00503 was discovered by Alexandr Ditkovsky from VS-COMPAS project in 2012, based on ROTSE-I/NSVS data. The AAVSO Variable Star Index suggests type RRC with Blazhko effect, the listed light elements are: HJD(max) = 2454663.561 + 0.41189×E. Based on the data from ROTSE-I/NSVS, ASAS-3 and Catalina Surveys, it is actually a double-mode RR Lyrae star, type RR(B), with the light elements tabulated below.

ModeFrequency, c/d Semi-amplitude, mag Period, days Epoch, JD
f1 2.427833 0.150 (CV, CSS), 0.208 (V, ASAS), 0.123 (R, NSVS) 0.411890 2455000.885
f0 1.810391 0.086 (CV, CSS), 0.116 (V, ASAS), 0.056 (R, NSVS) 0.552367 2455000.520
f1 + f0 4.23824 0.041 (CV, CSS) 0.235947 2455000.702
f1 – f0 0.617452 0.035 (CV, CSS) 1.61956 2455000.74

The period ratio of the first-overtone and fundamental modes is P1/P0 = 0.7457. J–K = 0.214 (2MASS); B–V = 0.217 (APASS). Combined brightness of two stars, GSC 0925-00503=var and GSC 0925-00363, was measured in the NSVS, the tabulated amplitudes are somewhat underestimated.

6. The variability of USNO-A2.0 0675-14795162 was reported by Keller et al. (2008; Id. 111137.2696). The variable was classified as an RR: star without light elements. Based on Catalina Surveys data, it is actually a double-mode RR Lyrae star, type RR(B), with the light elements tabulated below.

ModeFrequency, c/d Semi-amplitude, V mag Period, days Epoch, JD
f1 2.779415 0.163 0.359788 2454800.660
f0 2.069806 0.104 0.483137 2454800.795

The period ratio of the first-overtone and fundamental modes is P1/P0 = 0.7447. J–K = 0.391 , J–H = 0.388 (2MASS).

7. The variability of USNO-A2.0 0975-20240597 was discovered in 2013 by Igor Baluk, Sergei Dubrovski and Alexander Pobiyaha from Astrobloknot Team, based on CSS data. The light elements were given as: HJD(max) = 2455999.857 + 0.353608×E; the star shows Blazhko effect. Based on data from Catalina Surveys, it is actually a double-mode RR Lyrae star, type RR(B), with the light elements tabulated below.

ModeFrequency, c/d Semi-amplitude, V mag Period, days Epoch, JD
f1 2.827942 0.165 0.353614 2455000.555
f0 2.104448 0.059 0.475184 2455000.685
f1 + f0 4.93247 0.039 0.202738 2455000.594

The period ratio of the first-overtone and fundamental modes is P1/P0 = 0.7442. J–K = 0.288 (2MASS), B–V=0.15 (APASS).

Remarks:
We present a new investigation of seven known RR Lyrae variable stars. We analyzed all observations available for these stars in the Catalina Surveys (Drake et al. 2009), Northern Sky Variability Survey (NSVS , Woźniak et al. 2004), ASAS-3 (Pojmanski 2002) and SuperWASP (Butters et al. 2010) 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 RR Lyrae variables, pulsating in the first-overtone and fundamental modes.

Their period ratios, P1 / P0, are typical of radially pulsating double-mode RR Lyrae stars. Along with the light curves, we present power spectra of the RR Lyrae variables, for the raw data and after subtraction of the first-overtone oscillations. The structure of the power spectra shows that the secondary periods are real.

The SuperWASP observations are available as FITS tables, which were converted into ASCII tables using the OMC2ASCII program as described by Sokolovsky (2007).

The tabulated coordinates of the variables were drawn either from the UCAC4, 2MASS catalogs or from the GCVS (Samus et al. 2007–2013).

Acknowledgements: Thanks are due to Dr. K.V. Sokolovsky for his advice concerning data retrieving. The authors 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. Astrophys., 520, L10
Drake, A.J., Djorgovski, S.G., Mahabal, A., et al., 2009, Astrophys. J., 696, 870
Hoffmeister, C., 1963, Veröff. Sternwarte Sonneberg, 6, 1
Keller, S.C., Murphy, S., Prior, S., et al., 2008, Astrophys. J., 678, 851
Pojmanski, G., 2002, Acta Astron., 52, 397
Samus, N.N., Goranskij V.P., Durlevich O.V., Kazarovets E. V., Kireeva N.N., Pastukhova E.N., Zharova A.V., 2007–2013, General Catalogue of Variable Stars, Centre de Donnees Astronomiques de Strasbourg, B/gcvs
Sokolovsky, K.V., 2007, Perem. Zvezdy Prilozh., 7, No. 30
Woźniak, P.R., Vestrand, W.T., Akerlof, C.W., et al., 2004, Astron. J., 127, 2436



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