Peremennye Zvezdy

Peremennye Zvezdy (Variable Stars) 33, No. 4, 2013

Received 04 June; accepted 25 June.

Article in PDF

New Eclipsing Variable Star with Delta Scuti Component

V. Solovyov1, A. Samokhvalov2,3, B. Satovskiy3

  1. Kazan Federal University, Russia, e-mail: solo.vya@gmail.com;

  2. Surgut, Russia, e-mail: sav@surgut.ru;

  3. Astrotel Observatory, Carachay-Cherkessiya, Russia; e-mail: bsatovski@gmail.com


We present our discovery a new variable star USNO-A2.0 1350-17086180 from observations at the Astrotel-Caucasus Observatory. The object shows Algol-type eclipses and, simultaneously, low-amplitude, short-period pulsations.

1. Introduction

During observations of a field in Cepheus, we discovered a new Algol-type variable star with a pulsating Scuti component: USNO-A2.0 1350-17086180 ( , , J2000, 2MASS), with the () variability range. For the finding chart of the star, see Fig. 1. Using an extensive series of observations, we determined parameters of the photometric behavior of the system.

2. Observations and data reduction

Our observations were carried out at the Astrotel-Caucasus observatory, located at the Astronomical station of the Kazan Federal University in the Northern Caucasus, using a 300-mm Ritchey-Chretien telescope equipped with an unfiltered Apogee Alta U9000 CCD camera. A total of 2058 images with 5-minute exposures were obtained during 45 nights between JD 2455828 and JD 2456219. The numbers of observations on each of the observing nights are presented in Table 1; the observations are attached to the html version of this paper.

Table 1. Numbers of observations

Night 		JD No.of Night JD No. of Night JD No. of
No. observations No. observations No. observations

1		 2455828 11 16 2455925 40 31 2456185 48
2 2455833 50 17 2455926 20 32 2456186 48
3 2455842 50 18 2455930 38 33 2456188 28
4 2455843 60 19 2455956 28 34 2456189 52
5 2455873 72 20 2456109 7 35 2456190 51
6 2455879 75 21 2456115 19 36 2456195 44
7 2455880 95 22 2456116 5 37 2456196 45
8 2455881 72 23 2456153 21 38 2456197 2
9 2455883 85 24 2456173 2 39 2456200 44
10 2455884 55 25 2456174 40 40 2456201 48
11 2455888 29 26 2456175 42 41 2456202 52
12 2455895 35 27 2456177 40 42 2456216 95
13 2455900 73 28 2456182 53 43 2456217 72
14 2455901 75 29 2456183 45 44 2456218 70
15 2455902 12 30 2456184 44 45 2456219 24


For basic reductions for dark current, flat fields, bias and for removing cosmic rays hits, we used IRAF routines. For photometry of the new variable star, we applied VaST software by Sokolovsky and Lebedev (2005). The comparison star was USNO-A2.0 1350-17114431 = USNO-B1.0 1368-0511417 ( , , J2000, 2MASS; , , USNO-B1.0).

Unfiltered magnitudes were calibrated using the comparison star, assuming .

All times in this paper are expressed in terrestrial time in accordance with IAU recommendations (resolution B1 XXIII IAU GA).

3. Analysis of observations

3.1. Eclipses

For analysis of our photometrical observations, we used the Lafler-Kinman method (Lafler and Kinman 1965) implemented in Peranso software (http://www.peranso.com). Using this method, we determined the eclipsing system's orbital period to be . The depth of primary minima is and that of secondary minima, . The three primary minima we observed are listed in Table 2; all these times were determined using the method described by Kwee and van Woerden (1956).

Table 2. The observed primary minima

No. 		HJD

1		 2455881.2869 0.0006
2 2456187.4703 0.0004
3 2456219.3262 0.0004


The light elements of the primary eclipses are:


3.2. Pulsations

Using the prewhitening procedure of the Peranso software, we found the pulsation period of the  Scuti component to be . The variability amplitude is , rather typical of  Scuti stars. During our observations, we detected 101 maxima of the pulsation light curve, collected in Table 3.

Table 3. Observed maxima of pulsation light curve

No. 		HJD No. HJD

1 		2455842.374 0.001 0 0.000 52 2456175.426 0.003 5533 0.004
2 2455842.438 0.002 1 0.004 53 2456175.484 0.001 5534 0.002
3 2455842.499 0.002 2 0.005 54 2456177.412 0.002 5566 0.004
4 2455843.400 0.002 17 0.003 55 2456177.472 0.002 5567 0.004
5 2455843.464 0.003 18 0.007 56 2456182.345 0.005 5648 0.001
6 2455843.519 0.003 19 0.001 57 2456182.404 0.003 5649 0.000
7 2455873.193 0.003 512 0.000 58 2456182.468 0.003 5650 0.004
8 2455873.252 0.002 513 -0.001 59 2456183.427 0.002 5666 -0.001
9 2455873.314 0.002 514 0.001 60 2456183.489 0.002 5667 0.001
10 2455873.368 0.004 515 -0.005 61 2456184.393 0.004 5682 0.002
11 2455873.435 0.003 516 0.001 62 2456184.456 0.003 5683 0.005
12 2455879.277 0.002 613 0.005 63 2456185.416 0.002 5699 0.002
13 2455879.336 0.002 614 0.003 64 2456185.478 0.002 5700 0.004
14 2455879.400 0.002 615 0.007 65 2456186.384 0.002 5715 0.007
15 2455879.457 0.003 616 0.004 66 2456186.445 0.003 5716 0.008
16 2455880.171 0.003 628 -0.004 67 2456186.502 0.002 5717 0.005
17 2455880.237 0.002 629 0.002 68 2456188.483 0.002 5750 -0.001
18 2455880.295 0.002 630 -0.001 69 2456188.545 0.002 5751 0.001
19 2455880.357 0.002 631 0.001 70 2456189.384 0.002 5765 -0.003
20 2455880.418 0.003 632 0.002 71 2456189.451 0.002 5766 0.004
21 2455880.477 0.003 633 0.001 72 2456189.508 0.002 5767 0.001
22 2455881.377 0.002 648 -0.002 73 2456190.415 0.004 5782 0.005
23 2455881.442 0.003 649 0.003 74 2456190.472 0.005 5783 0.002
24 2455883.187 0.002 678 0.002 75 2456190.539 0.003 5784 0.009
25 2455883.250 0.002 679 0.005 76 2456195.406 0.002 5865 0.000
26 2455883.308 0.002 680 0.003 77 2456195.464 0.003 5866 -0.002
27 2455883.368 0.001 681 0.003 78 2456196.429 0.002 5882 0.000
28 2455883.435 0.002 682 0.009 79 2456196.488 0.002 5883 -0.001
29 2455884.274 0.002 696 0.006 80 2456200.412 0.002 5948 0.010
30 2455884.336 0.002 697 0.007 81 2456200.464 0.004 5949 0.002
31 2455884.389 0.004 698 0.000 82 2456200.524 0.003 5950 0.002
32 2455884.459 0.002 699 0.010 83 2456201.427 0.002 5965 0.002
33 2455888.242 0.002 762 0.001 84 2456201.549 0.001 5967 0.003
34 2455895.224 0.003 878 0.001 85 2456202.391 0.003 5981 0.003
35 2455895.284 0.002 879 0.000 86 2456202.453 0.003 5982 0.004
36 2455900.164 0.002 960 0.005 87 2456202.511 0.002 5983 0.002
37 2455900.216 0.002 961 -0.003 88 2456216.229 0.003 6211 -0.004
38 2455900.279 0.003 962 -0.001 89 2456216.296 0.003 6212 0.003
39 2455900.341 0.003 963 0.001 90 2456216.357 0.003 6213 0.004
40 2455900.398 0.003 964 -0.002 91 2456216.412 0.002 6214 -0.001
41 2455901.184 0.003 977 0.001 92 2456216.474 0.002 6215 0.001
42 2455901.242 0.004 978 -0.001 93 2456216.536 0.002 6216 0.002
43 2455901.303 0.003 979 0.000 94 2456217.317 0.002 6229 0.001
44 2455901.363 0.003 980 0.000 95 2456217.376 0.003 6230 0.000
45 2455901.422 0.003 981 -0.001 96 2456217.434 0.002 6231 -0.003
46 2455925.268 0.002 1377 0.008 97 2456217.498 0.002 6232 0.001
47 2455926.291 0.004 1394 0.008 98 2456218.342 0.002 6246 0.003
48 2455956.197 0.002 1891 -0.002 99 2456218.403 0.002 6247 0.003
49 2456153.397 0.002 5167 0.006 100 2456218.459 0.002 6248 -0.001
50 2456174.461 0.002 5517 0.002 101 2456218.521 0.002 6249 0.001
51 2456174.519 0.002 5518 0.000


The light elements of the pulsations are:


Having 101 maxima observed on a time span of 392 days, corresponding to 6249 pulsation cycles, we can fully explore possible variation of the pulsation period of the  Scuti component, starting with the light elements (2). We calculated pulsation maxima and determined residuals, also presented in the corresponding column of Table 3. The residuals suggest no variations of the pulsation period.

Using the light elements (1) and (2), we plotted the four light curves shown in Fig. 2. They illustrate the photometric behavior of the system.

We hope that the present study will stimulate new observations of this interesting star.

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

References:

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

Kwee, K., van Woerden, H. 1956, Bulletin of the Astronomical Institutes of the Netherlands, 12, 464

Lafler, J., Kinman, T.D. 1965, Astrophys. J., Suppl. Ser., 11, 216

Fig. 1. The finding chart of USNO-A2.0 1350-17086180.

Fig. 2. USNO-A2.0 1350-17086180 light curves. The upper left curve displays raw data with the orbital period; the upper right curve, raw data with the pulsation period; the bottom left curve, raw data with pulsations removed, folded with the orbital period; and the bottom right curve, raw data with eclipses removed, folded with the pulsation period.



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