Peremennye Zvezdy

"Peremennye Zvezdy",
Prilozhenie
,
vol. 9, N 20 (2009)

New Variable Stars Discovered Using the Tzec Maun Observatory Telescopes II

K. V. Sokolovsky#1,2, L. Elenin#3, N. Virnina#4
#1. Max Planck Institute for Radio Astronomy, Bonn, Germany;
#2. Astro Space Center of Lebedev Physical Institute, Moscow, Russia;
#3. Amateur astronomical society Astrogalaxy, Moscow, Russia;
#4. Odessa National University, Odessa, Ukraine

Received:   4.06.2009;   accepted:   19.06.2009
(E-mail for contact: ksokolov@mpifr-bonn.mpg.de)


#NameOtherCoord (J2000)TypeMaxMinSystemPeriodEpoch (JD)typeSpCommentL.CurveFind.ChartData
1 USNO-B1.0 1034-006830805 30 07.91, +13 24 24.4EW18.318.8R0.231062454741.9517min  pks0528_R_1155.pngpks0528_R_1155_chart.pngpks0528_R_1155_hjd.dat
2 USNO-B1.0 1035-006236005 30 20.54, +13 35 41.7EW17.4517.9R0.373112454742.9646min Comm. 2pks0528_R_0422.pngpks0528_R_0422_chart.pngpks0528_R_0422_hjd.dat
3 USNO-B1.0 1416-017780905 57 35.24, +51 38 17.2DSCT13.5313.63R0.0622682454866.7478max Comm. 35_cr_01677.png5_cr_01677_chart.png5_cr_1677_hjd.dat
4 USNO-B1.0 1415-017524105 58 10.71, +51 33 36.7EW16.0516.40R0.30672454866.7292min Comm. 45_cr_01170.png5_cr_01170_chart.png5_cr_1170_hjd.dat
5 USNO-B1.0 1415-017556105 59 16.43, +51 34 45.1EW17.017.5R0.28392454860.7900min Comm. 55_cr_01305.png5_cr_01305_chart.png5_cr_1305_hjd.dat
6 USNO-B1.0 1278-023970310 59 57.18, +37 50 20.5RR(B)15.516.5V0.352692454848.0016max Comm. 6mrk421_cv_03454.pngmrk421_cv_03454_chart.pngmrk421_cv_03454_hjd.dat
7 GSC 2521-00245, USNO-B1.0 1260-018750411 00 21.54, +36 03 19.9RRC14.415.0V0.314092454876.9789max  mrk421_cv_03064.pngmrk421_cv_03064_chart.pngmrk421_cv_03064_hjd.dat
8 USNO-B1.0 1264-018814011 03 08.38, +36 24 02.0RRAB15.817.0V0.62782454876.9329max  mrk421_cv_12144.pngmrk421_cv_12144_chart.pngmrk421_cv_12144_hjd.dat
9 GSC 3010-02260, USNO-B1.0 1277-023773711 03 08.87, +37 47 49.0RRC:13.613.8V0.217562454846.8843max Comm. 9mrk421_cv_02542.pngmrk421_cv_02542_chart.pngmrk421_cv_02542_hjd.dat
10 GSC 2521-00840, USNO-B1.0 1263-018951211 03 30.05, +36 22 47.6EW12.2313.37V0.367842454847.8718min Comm. 10mrk421_cv_02183.pngmrk421_cv_02183_chart.pngmrk421_cv_02183_hjd.dat
11 USNO-B1.0 1284-021212511 04 29.18, +38 29 20.4EW15.6516.2V0.256762454847.8694min Comm. 11mrk421_cv_02260.pngmrk421_cv_02260_chart.pngmrk421_cv_02260_hjd.dat
12 GSC 2521-00328, USNO-B1.0 1262-018846911 05 45.89, +36 15 55.3EW13.614.0V0.282652454856.9317min Comm. 12mrk421_cv_01506.pngmrk421_cv_01506_chart.pngmrk421_cv_01506_hjd.dat
13 USNO-B1.0 1257-018916411 10 21.81, +35 46 50.6RR(B)15.216.1V0.350512454851.7556max  mrk421_cv_00310.pngmrk421_cv_00310_chart.pngmrk421_cv_00310_hjd.dat

Comments:


2. MinII = 17.85.

3. Two pulsation frequencies can be identified: 16.05974 +/-0.00049 c/d, half-amplitude 0.025 +/-0.001 mag, and 14.40987 +/-0.00057 c/d, half-amplitude 0.022 +/-0.001 mag. Light elements: HJDmax(TT) = 2454866.7478 + 0.062268 x E and HJDmax(TT) = 2454874.7290 + 0.069397 x E.

4. MinII = 16.25. Unequal minima (not typical for EW eclipsing binaries) may be a result of high starspot activity.

5. MinII = 17.35.

6. 2MASS 10595715+3750203 (J = 15.385 +/-0.042, H = 15.320 +/-0.087, Ks = 15.215 +/-0.133 measured on JD 2450912.8110), infrared colors are consistent with spectral type A, typical of RR Lyrae variable stars. This is a double-mode RR Lyrae variable star with the fundamental frequency 2.10743 +/-0.00020 c/d, half-amplitude 0.161 +/-0.007 mag, and first overtone frequency 2.83538 +/-0.00014 c/d, half-amplitude 0.229 +/-0.006 mag. The first overtone to fundamental mode period ratio is 0.743. Light elements for the fundamental mode pulsation: HJDmax(TT) = 2454876.9243 + 0.47451 x E; for the first overtone: HJDmax(TT) = 2454848.0016 + 0.35269 x E.

9. 2MASS 11030886+3747491 (J = 12.604 +/-0.022, H = 12.342 +/-0.023, Ks = 12.315 +/-0.020 measured on JD 2450912.8387), infrared colors are consistent with F spectral type (Bessell & Brett 1988). Classification as an EW eclipsing binary with the light elements HJDmin(TT) = 2454875.7161 + 0.43511 x E is also possible.

10. MinII = 12.33.

11. MinII = 16.05.

12. MinII = 13.95. 13. Case A-F 716, an A-F spectral type star according to low-dispersion spectroscopy by Pesch & Sanduleak (1989) which is in agreement with 2MASS colors: 2MASS 11102180+3546502 J = 14.934 +/-0.038, H = 14.864 +/-0.059, Ks = 14.567 +/-0.093. The star is a double-mode RR Lyrae variable with the fundamental frequency 2.12227 +/-0.00016 c/d, half-amplitude 0.141 +/-0.006 mag, and the first overtone frequency 2.85296 +/-0.00011 c/d, half-amplitude 0.213 +/-0.006 mag. The first overtone to fundamental mode period ratio is 0.744, typical of double-mode RR Lyrae stars (see e.g. Wils 2009). Light elements for the fundamental mode: HJDmax(TT) = 2454847.9552 + 0.47119 x E; for the first overtone: HJDmax(TT) = 2454851.7556 + 0.35051 x E.

Remarks:
We present a list of variable stars discovered using remotely controlled telescopes of the Tzec Maun observatory. The telescope parameters are presented in Table 1. Table 2 presents the observation log.

Telescope D (mm) F (mm) CCD camera Location
Maksutov-Newton 350 1330 SBIG ST-10E Mayhill, New Mexico, USA
Takahashi FSQ 106 106 530 SBIG STL-11000MMayhill, New Mexico, USA
Takahashi TOA-150 150 1100 SBIG STL-6303 Pingelly, Western Australia
Table 1. Telescopes used for observations


USNO-B1.0 TelescopeFilterDatesNCalibration
1034-0068308Maksutov-Newton R 2454740 - 2454856 97a
1035-0062360Maksutov-Newton R 2454740 - 2454858 106a
1416-0177809Maksutov-Newtonclear2454853 - 2454907 277b
1415-0175241Maksutov-Newtonclear2454853 - 2454907 286b
1415-0175561Maksutov-Newtonclear2454853 - 2454907 284b
1278-0239703 FSQ 106 clear2454846 - 2454952 679c
1260-0187504 FSQ 106 clear2454846 - 2454926 662c
1264-0188140 FSQ 106 clear2454846 - 2454921 347c
1277-0237737 FSQ 106 clear2454843 - 2454926 741c
1263-0189512 FSQ 106 clear2454843 - 2454926 718c
1284-0212125 FSQ 106 clear2454843 - 2454926 638c
1262-0188469 FSQ 106 clear2454843 - 2454926 735c
1257-0189164FSQ 106,TOA-150clear2454846 - 2454946 814c
Table 2. Observation log
Magnitude scale was calibrated using:
(a) R magnitudes of comparison stars in the field of PKS 0528+135 (González-Pérez et al. 2001);
(b) assuming R = 15.0 for the comparison star USNO-B1.0 1415-0175230 (05:58:08.45 +51:33:34.8, J2000; R1 = 14.77, R2 = 15.27, Monet et al. 2003);
(c) V magnitudes of the comparison stars in the field of Mrk 421 (Villata et al. 1998).

The VaST software (Sokolovsky & Lebedev 2005) was used for the preliminary data reduction and detection of variable stars. Our final lightcurve analysis was conducted using two different methods. First, all lightcurves were analyzed using the Lafler-Kinman method which has the advantage that it does not assume any particular shape of a phased lightcurve. For three variable stars which show multi-periodic behavior, the final analysis was conducted using the Discrete Fourier Transform (DFT) method implemented in the Period04 software developed by Lenz & Breger (2005). For those three stars, the lightcurve approximation with a superposition of two sine waves seems to be reasonable. The errors in frequencies and amplitudes derived from the DFT analysis were estimated with Monte Carlo simulation.

Identification with the 2MASS catalog (Skrutskie et al. 2006) is provided whenever the simultaneous infrared photometric data from this catalog may improve the variability type classification. All coordinates in this paper were taken from the USNO-B1.0 catalog (Monet et al. 2003). The finding charts are made from POSS-II red images.

It was a surprise to find two double-mode RR Lyrae variables among five RR Lyrae stars identified in a single 234' x 156' field-of-view.

Acknowledgments
This research is based on data collected with the Tzec Maun Observatory, operated by the Tzec Maun Foundation. The authors are grateful to Ron Wodaski (director of the observatory) and Donna Brown-Wodaski (director of the Tzec Maun Foundation). This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the UMass/IPAC-Caltech, funded by the NASA and the NSF, the Aladin interactive sky atlas, operated at CDS, Strasbourg, France and the International Variable Star Index (VSX) operated by the AAVSO. K. Sokolovsky was supported by the International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the universities of Bonn and Cologne. This research has made use of NASA's Astrophysics Data System. We would like to thank S.V. Antipin for helpful discussion of the results, V.P. Goranskij for providing his software which implements the Lafler-Kinman method and E. Angelakis for reviewing this manuscript.

References:
Bessell, M.S., Brett, J.M., 1988, PASP, 100, 1134
González-Pérez, J.N., Kidger, M.R., Martín-Luis, F., 2001, Astron. J., 122, 2055
Lenz, P., Breger, M., 2005, Comm. of Asteroseismology, 146, 53
Monet, D.G., Levine, S.E., Canzian, B., et al., 2003, Astron. J., 125, 984
Pesch, P., Sanduleak, N., 1989, Astrophys. J. Suppl., 71, 549
Skrutskie, M.F., Cutri, R.M., Stieming, R., et al., 2006, Astron. J., 131, 1163
Sokolovsky, K., Lebedev, A., 2005, in 12th Young Scientists' Conference on Astronomy and Space Physics, Kyiv, Ukraine, April 19-23, 2005, eds.: Simon, A.; Golovin, A., p.79
Villata, M., Raiteri, C.M., Lanteri, L., et al., 1998, Astron. and Astrophys. Suppl., 130, 305
Wils, P., 2009, IBVS, No. 5873



Main Page | Search
Astronet | SAI | INASAN

Report problems