New Variable Stars at the Borderline of Ophiuchus and Serpens

V. Solovyov^#1, A. Samokhvalov^#2, T. Kryachko^#3, B. Satovskiy^#3

#1. Kazan Federal University, Kazan, Russia; #2. Surgut, Russia; #3. Astrotel Observatory, Karachay-Cherkessia, Russia

Received:   24.03.2013;   accepted:   14.06.2013
(E-mail for contact: solo.vya@gmail.com, sav@surgut.ru, bredfild@mail.ru, bs25@mail.ru)

Comments:


1. Maxima:

HJD(TT)	±
2455769.437	0.003
2456047.424	0.005
2456049.468	0.003
2456189.2651	0.0008

2. A close pair of two stars: USNO-A2.0 0900-12932590 and 2MASS 18283560+0259315. USNO-A2.0 0900-12932590 varies. Infrared colors J–H = 1.044, H–K = 0.344 and J–K = 1.388 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maximum: HJD(TT) 2456186.7±0.5.

3. A close triplet of stars USNO-A2.0 0900-12933840, 2MASS 18283742+0318015, and a faint star not contained in any catalogues. USNO-A2.0 0900-12933840 varies.
Maximum: HJD(TT) 2456200.2274±0.0009.

4. Primary minima:

HJD(TT)	±
2455344.3523	0.0007
2456173.2661	0.0008
2456183.2770	0.0004
2456200.2275	0.0009

Min_II = 16^m.26.

5. Infrared colors J–H = 0.973, H–K = 0.340 and J–K = 1.313 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

6. Infrared source IRAS 18264+0329. Infrared colors J–H = 1.102, H–K = 0.400 and J–K = 1.502 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and LB classification.

7. Infrared colors J–H = 1.002, H–K = 0.345 and J–K = 1.347 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maxima:

HJD(TT)	±
2455747.0	0.9
2456199.5	0.6

9. Period 0^d.9810 is also possible.

10. Infrared colors J–H = 1.026, H–K = 0.503 and J–K = 1.529 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maxima:

HJD(TT)	±
2455803	1
2456208	1

11. A close pair of two stars: USNO-A2.0 0900-12961808 and a faint star, not contained in any catalogues. USNO-A2.0 0900-12961808 varies. Infrared colors J–H = 1.036, H–K = 0.374 and J–K = 1.410 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

12. Primary minima:

HJD(TT)	±
2455344.3580	0.0004
2455772.4432	0.0007
2455785.3063	0.0002
2455815.3373	0.0008
2456049.4515	0.0010
2456052.511	0.001
2456173.2469	0.0002

Min_II = 13^m.95.

13. Infrared colors J–H = 1.021, H–K = 0.333 and J–K = 1.354 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maximum: HJD(TT) 2455773±1.

14. Infrared colors J–H = 1.079, H–K = 0.488 and J–K = 1.567 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and LB classification.

15. Infrared colors J–H = 1.071, H–K = 0.431 and J–K = 1.502 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maximum: HJD(TT) 2455778.0±1.5.

16. Infrared colors J–H = 1.094, H–K = 0.383 and J–K = 1.477 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

17. Infrared colors J–H = 0.848, H–K = 0.305 and J–K = 1.153 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maximum: HJD(TT) 2456203±2.

18. Infrared colors J–H = 1.043, H–K = 0.501 and J–K = 1.544 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maximum: HJD(TT) 2455757±1.

19. Infrared colors J–H = 0.933, H–K = 0.337 and J–K = 1.270 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maxima:

HJD(TT)	±
2455741	2
2456188	1

20. Maxima:

HJD(TT)	±
2455772.4814	0.0008
2455784.3359	0.0009
2456183.258	0.002
2456218.2414	0.0005

21. A close pair of two stars: USNO-A2.0 0900-13004335 and a faint star, not contained in any catalogues. USNO-A2.0 0900-13004335 varies. Infrared colors J–H = 1.000, H–K = 0.385 and J–K = 1.385 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

22. Infrared colors J–H = 1.066, H–K = 0.281 and J–K = 1.347 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

23. Infrared colors J–H = 1.037, H–K = 0.440 and J–K = 1.477 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maxima:

HJD(TT)	±
2455734.6	0.5
2456180.8	0.7

24. A close pair of two stars: USNO-A2.0 0900-13012157 and a faint star, not contained in any catalogues. USNO-A2.0 0900-13012157 varies. Infrared colors J–H = 1.080, H–K = 0.296 and J–K = 1.376 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

25. Infrared colors J–H = 1.131, H–K = 0.455 and J–K = 1.586 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and LB classification.

26. A close triplet of stars USNO-A2.0 0900-13019383 and two faint stars, not contained in any catalogues. USNO-A2.0 0900-13019383 varies. Infrared colors J–H = 1.101, H–K = 0.429 and J–K = 1.530 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maxima:

HJD(TT)	±
2455736	1
2456185	1

27. A close triplet of stars USNO-A2.0 0900-13022138, NOMAD1 0935-0383912 and NOMAD1 0935-0383907. USNO-A2.0 0900-13022138 varies. Infrared colors J–H = 1.160, H–K = 0.462 and J–K = 1.622 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

28. Infrared colors J–H = 1.103, H–K = 0.382 and J–K = 1.485 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

29. Blazhko effect with a period of 53^d.4.
Maxima:

HJD(TT)	±
2455344.4166	0.0006
2455432.366	0.001
2456173.3065	0.0004
2456195.2942	0.0008

30. USNO-A2.0-0900-13034971 is located near the position of a known variable star, NSVS 13891310, discovered by Benko and Csubry (2007) using NSVS data. The angular resolution of the ROTSE-I instrument is insufficient for a decision which star varies. Using our telescope, we confidently identified the variable star and determined its variability parameters. Infrared colors J–H = 1.059, H–K = 0.524 and J–K = 1.583 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and Mira classification.

31. Infrared colors J–H = 0.772, H–K = 0.295 and J–K = 1.067 (2MASS) are consistent with the K-M spectral type (Bessell and Brett 1988) and BY: classification.

32. Infrared colors J–H = 0.778, H–K = 0.245 and J–K = 1.023 (2MASS) are consistent with the K-M spectral type (Bessell and Brett 1988) and SR: classification.
Maxima:

HJD(TT)	±
2455733.9	0.7
2455781.6	0.7
2456193.4	0.3

33. Infrared colors J–H = 1.122, H–K = 0.482 and J–K = 1.604 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.
Maxima:

HJD(TT)	±
2455747.9	0.8
2456178.9	0.6

34. Infrared colors J–H = 1.105, H–K = 0.459 and J–K = 1.564 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

35. Infrared colors J–H = 1.125, H–K = 0.424 and J–K = 1.549 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

36. Primary minima:

HJD(TT)	±
2456174.3115	0.0006
2456195.2510	0.0006

Min_II = 14^m.48.

37. Infrared colors J–H = 1.202, H–K = 0.438 and J–K = 1.640 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988) and SR: classification.

Remarks:
During observations of a field at the borderline of Ophiuchus and Serpens, we discovered 37 new variable stars. Our observations were carried out at the Astrotel-Caucasus observatory, located at the Astronomical station of the Kazan Federal university, using the 300-mm Ritchey-Chretien telescope, equipped with an unfiltered Apogee Alta U9000 CCD camera. A total of 1327 images with 5-minute exposures were obtained on JD 2455018–2456218. For basic reductions for dark current, flat fields, bias and for removing cosmic-ray hits we used IRAF routines. For search and photometry of new variable stars, we applied VaST software by Sokolovsky and Lebedev (2005). The comparison star was USNO-A2.0 0900-13006962 = USNO-B1.0 0936-0378151, α = 18^h30^m09^s.78, δ = +03°36′ 55″.1 (J2000, 2MASS), R₁ = 13^m.73, R₂ = 13^m.72 (USNO-B1.0). Unfiltered magnitudes were calibrated using the comparison star, assuming R_comp = 13^m.725. The coordinates of the variable stars in the table were drawn from the 2MASS catalogue (Skrutskie et al. 2006). For search for periods and epochs of extrema we use Peranso software.

Acknowledgements: We would like to thank S.V. Antipin and N.N. Samus for helpful discussion.

References:
Benko, J.M., Csubry, Z., 2007, Acta Astron., 57, 73
Bessell, M.S., Brett, J.M., 1988, Publ. Astron. Soc. Pacific, 100, 1134
Skrutskie, M.F., Cutri, R.M., Stiening, 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