Peremennye Zvezdy

Peremennye Zvezdy (Variable Stars) 28, No. 9, 2008

Received 28 October; accepted 15 December.

Article in PDF

RS CVn STARS AMONG VARIABLES WITH POSSIBLE CW CLASSIFICATION IN THE ASAS-3 SURVEY

L.N. Berdnikov1, E.N. Pastukhova2

Sternberg Astronomical Institute, Moscow State University, Russia; e-mail: berdnik@sai.msu.ru

Institute of Astronomy, Russian Academy of Sciences, Russia; e-mail: pastukhova@sai.msu.ru


We present a list of 109 probable RS CVn variables among stars in the ASAS-3 catalog with Population II Cepheid classification as the main one or an alternative one. These stars are identified with X-ray sources and have light curves (from ASAS-3 data) in no contradiction with the suggested RS CVn classification.

Classical Cepheids are very important as distance indicators as well as for studies of stellar evolution, structure and kinematics of our Galaxy. An extensive program of Cepheid studies is under way in the Sternberg Astronomical Institute and Institute of Astronomy (Russian Academy of Sciences) (Samus et al. 2007). Population II Cepheids are also of astrophysical interest, and some of them enter our programs of observations. We are interested in the largest possible volume of our Cepheid sample and in clear separation of Population I and Population II Cepheids from objects of other nature resembling them by periods and light-curve shapes.

Recently, thousands of new variable stars were discovered in the ASAS-3 automatic survey (Pojmanski 2002). Many of them have ASAS-3 classification as Cepheids or possible Cepheids. However, our trial observations of objects from the ASAS-3 variable star catalog revealed that some stars had photometric behavior incompatible with their Cepheid classification. Most of them can be identified with Galactic X-ray sources and thus, most probably, are RS CVn variables.

In this study, we analyzed the complete list of stars in the ASAS-3 variable-star catalog with Population II (CW) classification as the main one or as an alternative possibility. Among stars we were able to identify with known X-ray sources of the following catalogs: 1RXS (Voges et al. 1999, 2000), 1RXH (ROSAT Consortium 2000), 1WGA (White et al. 2000), and 2E (Harris 1994), 109 objects have light curves (from ASAS-3 data) permitting us to consider them RS CVn variables.

The list of our RS CVn candidates is presented in the Table. The lines of the Table contain: coordinates (right ascension and declination) from the 2MASS catalog; the X-ray catalog identification; the ASAS-3 catalog identification; the star's variability period from the ASAS-3 catalog; our revised period value (if available); the GCVS/NSV designation and GCVS type (if available). The revised periods are often twice shorter than those suggested in the ASAS-3 catalog.

Note that the star ASAS-3 032406+0729.5 is probably an eclipsing RS CVn star, the only case in our sample. Alternatively, it could even be an EW variable with the period 067645. The ASAS-3 data give no possibility to rule out any of these options.

The star ASAS-3 082250+0151.6 (NSV 17868) was correctly identified as an RS CVn variable in Henry et al. (1995). The period given for this star in the Table is from the cited paper, we retained the star in the Table for the sake of completeness.

Acknowledgements: The authors gratefully acknowledge support for this work by research funding awarded through the Russian Foundation of Basic Research (RFBR, grants 07-02-00380 and 08-02-00375), through the Program of Support for Leading Scientific Schools of Russia, and through the program "Origin and Evolution of Stars and Galaxies" of the Presidium of Russian Academy of Sciences. Thanks are due to the Editor, N.N. Samus, for valuable suggestion towards improvement of the manuscript.

References:

Harris, D.E., Forman, W., Gioa, I.M., et al., 1994, VizieR On-line Data Catalog: IX/13

Henry, G.W., Fekel, F.C., Hall, D.S., 1995, Astron. J., 110, 2926

Pojmanski, G., 2002, Acta Astron., 52, 397

ROSAT Consortium, 2000, VizieR On-line Data Catalog: IX/28A

Samus, N.N., Antipin, S.V., Berdnikov, L.N., et al., 2007, Odessa Astron. Publ., 20, 197

Voges, W., Aschenbach, B., Boller, Th., et al., 1999, VizieR On-line Data Catalog: IX/10A

Voges, W., Aschenbach, B., Boller, Th., et al., 2000, VizieR On-line Data Catalog: IX/29

White, N.T., Giommi, P., Angelini, L., 2000, VizieR On-line Data Catalog: IX/31

Table. RS CVn variables among stars with CW classification in the ASAS-3 catalogue
2MASS coordinates X-ray Identification ASAS-3 , GCVS,
(2000.0) ASAS-3 NSV
00220344 +130335 2 1RXS J002204.0+130351 002203+1303.6 3462
00 41 34.48 +21 18 02.6 1RXS J004133.3+211817 004135+2118.1 5.882 2941
01 05 06.40 +09 35 08.3 1RXS J010506.8+093505 010507+0935.1 9.98
01 05 15.94 +01 59 14.2 1RXH J010516.0+015915 010516+0159.2 6.9058
01 21 39.26 +25 17 47.4 1RXS J012140.1+251743 012139+2517.8 12.994
01 22 15.44 +20 21 30.2 1RXS J012215.4+202139 012216+2021.5 10.21
01 36 27.81 +25 08 35.6 1RXS J013628.0+250835 013628+2508.5 1.335951
02 20 32.40 +20 07 28.7 1RXS J022033.7+200759 022032+2007.5 18.36 9.18
02 42 36.22 +07 17 26.1 2E 647 024236+0717.4 52.84
03 12 34.29 +09 44 57.0 1RXS J031232.3+094426 031234+0944.9 12.419 6.209
03 24 05.62 +07 29 27.0 1RXS J032405.3+072926 032406+0729.5 40.89 20.43
04 18 10.78 +23 17 04.9 1RXS J041811.1+231700 041811+2317.1 1.8969 1.8787 NSV 15941
04 30 49.18 +21 14 10.6 1RXS J043049.5+211356 043049+2114.2 2.835
04 42 18.61 +01 17 39.9 1RXS J044219.2+011741 044219+0117.7 8.771
04 48 57.99 +19 14 56.1 1RXS J044858.4+191500 044858+1915.0 16.055
05 00 49.28 +15 27 00.6 1RXS J050049.1+152658 050049+1527.0 2.763
05 13 05.82 +08 51 31.4 1RXS J051305.8+085122 051306+0851.5 4.0182
05 13 19.01 +01 34 47.0 1RXS J051319.1+013525 051319+0134.8 7.431 3.656
05 22 54.79 +08 58 04.7 1RXS J052254.9+085803 052255+0858.1 5.941
05 36 30.99 +11 19 40.2 1RXS J053632.0+111935 053631+1119.7 12.285
05 39 14.80 +00 31 13.4 1RXS J053914.8+003110 053915+0031.2 8.105 4.0525
05 39 27.10 -03 47 04.4 1RXS J053927.0-034655 053927-0347.1 1.92952
05 39 58.77 +07 08 30.5 1RXS J053959.1+070832 053959+0708.5 2.1133
05 43 52.80 -02 50 43.5 1RXS J054353.4-025038 054353-0250.7 1.73393 6.64
07 16 50.45 +21 45 00.1 1RXS J071650.8+214509 071650+2145.0 80.7 40.35
08 22 49.96 +01 51 33.6 1RXS J082250.2+015152 082250+0151.6 6.6 3.296 NSV 17868
08 35 26.86 +24 15 39.6 1RXS J083526.4+241538 083527+2415.7 20.74
08 49 19.81 +05 52 29.8 1RXS J084919.7+055234 084920+0552.5 14.593 7.2965
10 12 17.64 -03 44 40.4 1RXS J101217.2-034442 101218-0344.8 21.535
10 13 23.88 +12 08 45.8 1RXS J101324.2+120849 101324+1208.7 34.23 34.00 EQ Leo (LB:)
10 30 02.68 -00 47 32.0 1RXS J103002.8-004726 103003-0047.5 30.74 15.37
10 39 59.00 +13 27 22.1 1RXS J103958.4+132733 103959+1327.4 6.198 6.217
10 59 20.11 +04 53 17.4 1RXS J105920.5+045308 105920+0453.3 2.1155 17.50
11 56 51.66 +08 27 21.9 1RXS J115651.8+082726 115652+0827.3 4.4821 4.402
12 03 15.65 +16 06 37.7 1RXS J120316.6+160634 120316+1606.6 3.5274 3.530
12 15 30.72 -39 48 42.6 1RXS J121527.9-394843 121531-3948.7 5.067861
12 16 52.98 +05 41 26.2 1WGA J1216.8+0541 121653+0541.4 13.94847 14.26
12 19 06.45 +18 21 21.2 1RXS J121906.1+132119 121906+1821.4 5.653 5.658 FN Com (LB)
12 25 49.91 +09 45 46.6 1RXS J1225.8 +0945 122550+0945.8 7.736 7.718
12 48 48.20 +14 45 32.3 1RXS J124848.7+144531 124848+1445.5 2.45647 2.455
12 50 51.67 -51 56 36.1 1RXS J125051.3-515655 125051-5156.6 2.76116
13 05 29.53 +12 49 45.1 1RXS J130528.5+124925 130529+1249.6 3.6885
13 12 53.57 +08 23 35.4 1RXS J131253.3+082341 131254+0823.6 9.886 9.870 NSV 19563
13 56 49.20 +24 29 27.4 1RXS J135649.4+242941 135649+2429.4 1.08555 12.23
14 07 01.16 -42 33 00.7 1RXS J140657.7-423325 140701-4233.0 1.693846
15 02 07.25 -12 01 51.7 1RXS J150206.0-120206 150207-1201.9 2.684136 2.6831
15 02 47.37 +22 18 20.7 1RXS J150246.8+221821 150248+2218.4 7.395547
15 17 21.23 -19 00 59.0 1RXS J151720.9-190103 151721-1901.0 11.33163 11.38
15 22 16.27 -26 52 25.2 1RXS J152216.6-265215 152216-2652.4 6.835125
15 23 46.11 -00 44 24.7 1RXS J152346.8-004434 152346-0044.4 11.561 11.685
15 35 07.61 -08 49 49.5 1RXS J153506.2-085002 153508-0849.8 39.44995 19.725
15 36 34.46 +12 19 31.5 1RXS J153633.6+121919 153634+1219.5 5.4026 5.407
15 48 40.95 -03 10 44.2 1RXS J154840.5-031106 154841-0310.7 3.8587 1.9236
15 51 07.58 +11 16 18.8 1RXS J155108.0+111559 155108+1116.3 6.606 6.603
15 54 44.94 -07 52 04.5 1RXS J155442.6-075142 155445-0752.0 5.617744 5.624
15 55 06.71 -19 46 31.3 1RXS J155506.8-194638 155507-1946.5 4.877127 4.880
15 57 06.80 -87 29 49.0 1RXS J155706.8-872949 155703-8730.1 3.115622 3.114
16 02 53.96 -20 22 48.1 1RXS J160254.9-202242 160254-2022.8 1.95349
16 07 04.28 +02 38 24.4 1RXS J160704.4+023823 160704+0238.4 3.7836

Table 1. Continued
2MASS coordinates X-ray Identification ASAS-3 , GCVS,
(2000.0) ASAS-3 NSV
16093805 +055237 2 1RXS J160938.4+055238 160938+0552.6 1085670 PX Ser (LB:)
16 19 59.93 +04 36 46.8 1RXS J161959.5+043636 162000+0436.8 1.438 1437
16 23 07.83 -23 00 59.7 1RXS J162308.8-230046 162308-2301.0 8.107618 4.0538
16 24 02.03 -29 10 44.9 1RXS J162402.5-291042 162402-2910.8 4.018315
16 24 23.39 +04 45 22.1 1RXS J162423.5+044507 162423+0445.4 9.929 4.963
16 25 10.00 +05 14 54.0 1RXS J162509.9+051446 162510+0514.9 3.4482
16 49 42.93 +22 20 03.8 1RXS J164943.4+222009 164943+2220.1 11.586
16 53 57.72 +07 34 50.4 1RXS J165357.6+073450 165358+0734.8 11.58509 11.510
17 03 13.52 +24 53 21.0 1RXS J170313.2+245332 170313+2453.3 11.565
18 46 52.56 -62 10 36.7 1RXS J184657.3-621037 184653-6210.3 5.373217 NSV 24575
19 05 25.05 -78 26 44.3 1RXS J190524.3-782658 190525-7826.8 2.8037
19 11 34.70 -34 35 08.8 1RXS J191134.7-343500 191135-3435.2 3.378621
19 17 43.75 -44 00 16.4 1RXS J191744.3-440021 191743-4400.3 9.424
19 39 06.45 -25 44 05.7 1RXS J193906.7-254358 193906-2544.1 12.745 12.76
20 01 51.98 -17 52 00.9 1RXS J200152.7-175211 200152-1752.0 6.579693
20 05 56.41 -32 16 59.2 1RXS J200556.1-321651 200556-3217.0 8.307
20 09 55.06 -45 59 45.2 1RXS J200955.9-460002 200955-4559.8 10.705
20 19 02.95 -14 02 04.5 1RXS J201903.1-140205 201903-1402.1 11.722 11.794
20 28 42.27 -09 43 17.0 1RXS J202843.1-094217 202842-0943.3 2.40015 2.402
20 36 08.30 -36 07 11.5 1RXS J203608.6-360713 203609-3607.2 2.1256
20 41 42.25 -22 19 20.5 1RXS J204142.6-221910 204142-2219.4 5.2987 5.3080 NSV 25239
20 44 30.10 -00 28 45.5 1RXS J204430.1-002845 204430-0028.6 5.874621
20 48 59.59 -06 44 54.4 1RXS J204859.5-064453 204900-0644.9 1.93626
20 49 22.86 +06 47 39.3 1RXS J204924.0+064737 204923+0647.6 8.958
21 01 21.54 -49 33 04.6 1RXS J210121.2-493322 210121-4933.1 6.235 6.238
21 10 44.82 +16 23 23.7 1RXS J211044.8+162312 211045+1623.4 10.576 10.590
21 10 54.19 +08 58 16.4 1RXS J211053.1+085810 211055+0858.2 13.988
21 13 05.27 -17 29 12.6 1RXS J211305.8-172912 211305-1729.2 4.9274 4.820
21 16 32.71 +19 42 13.0 1RXS J211633.6+194214 211633+1942.2 15.246
21 20 44.09 -54 37 59.3 1RXS J212043.3-543801 212044-5438.0 2.39861 2.3988
21 41 05.79 +02 22 15.4 1RXS J214108.2+022239 214106+0222.2 10.956
21 56 16.94 -40 08 27.2 1RXS J215616.4-400829 215617-4008.4 2.7398 2.7388
21 57 51.47 -68 12 50.1 1RXS J215753.2-681237 215752-6812.8 3.3765 NSV 25792
22 00 18.93 -10 02 47.8 1RXS J220019.8-100300 220019-1002.8 7.114
22 18 46.62 -84 38 29.6 1RXS J221851.8-843847 221846-8438.5 15.231 15.28
22 20 07.49 -48 37 38.4 1RXS J222008.8-483734 222008-4837.6 2.9028 2.901
22 23 00.44 -03 22 56.4 1RXS J222259.9-032303 222300-0322.9 7.593 7.589 NSV 25885
22 38 35.71 -63 34 21.4 1RXS J223836.2-633439 223836-6334.3 1.10603 1.1138 NSV 14251
22 42 26.53 -34 04 29.4 1RXS J224227.1-340434 224226-3404.5 11.53804 11.56
22 46 46 13 -20 58 37.9 1RXS J224647.8-205837 224646-2058.6 5.0237
22 47 05.53 +26 52 54.7 1RXS J224705.3+265257 224705+2652.9 2.2207
22 47 22.72 +23 13 16.7 1RXS J224721.8+231256 224723+2313.4 5.543 5.541
22 56 58.59 -45 13 20.4 1RXS J225659.0-451319 225659-4513.3 9.609 9.590
22 57 26.02 -56 45 41.1 1RXS J225725.9-564544 225726-5645.7 6.0245
23 08 40.17 -16 22 59.9 1RXS J230841.0-162313 230840-1623.0 0.83783 5.160
23 10 34.25 +09 29 51.2 1RXS J231034.3+093000 231034+0929.9 3.7693 3.772
23 12 29.01 +17 09 21.8 1RXS J231229.1+170935 231229+1709.4 3.0896
23 14 55.88 +27 39 59.3 1RXS J231456.5+273957 231456+2740.0 11.75
23 17 32.21 -52 48 07.5 1RXS J231732.2-524807 231733-5248.2 11.084 11.223
23 50 51.08 -01 09 22.6 1RXS J235051.1-010916 235051-0109.4 5.6184





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