2001A&A...370..157S


Query : 2001A&A...370..157S

2001A&A...370..157S - Astronomy and Astrophysics, volume 370, 157-169 (2001/4-4)

ROSAT all-sky survey of W Ursae Majoris stars and the problem of supersaturation.

STEPIEN K., SCHMITT J.H.M.M. and VOGES W.

Abstract (from CDS):

From ROSAT all-sky survey (RASS) data we obtained X-ray fluxes for 57 W UMa type contact systems. In our sample we detected three stars which are the shortest period main sequence binaries ever found as X-ray sources. For stars with (B-V)0<0.6 the normalized X-ray flux decreases with a decreasing color index but for (B-V)0>0.6 a plateau is reached, similar to the saturation level observed for single, rapidly rotating stars. The X-ray flux of W UMa stars is about 4-5 times weaker than that of the fastest rotating single stars. Because early type, low activity variables have longer periods, an apparent period-activity relation is seen among our stars, while cool stars with (B-V)0>0.6 and rotation periods between 0.23 and 0.45 days do not show any such relation. The lower X-ray emission of the single, ultra fast rotators (UFRs) and W UMa stars is interpreted as the result of a decreased coronal filling factor. The physical mechanisms responsible for the decreased surface coverage differs for UFRs and W UMa systems. For UFRs we propose strong polar updrafts within a convection zone, driven by nonuniform heating from below. The updrafts should be accompanied by large scale poleward flows near the bottom of the convective layer and equatorward flows in the surface layers. The flows drag dynamo generated fields toward the poles and create a field-free equatorial region with a width depending on the stellar rotation rate. For W UMa stars we propose that a large scale horizontal flow embracing both stars will prevent the magnetic field from producing long-lived structures filled with hot X-ray emitting plasma. The decreased activity of the fastest rotating UFRs increases the angular momentum loss time scale of stars in a supersaturated state. Thus the existence of a period cutoff and a limiting mass of W UMa stars can be naturally explained.

Abstract Copyright:

Journal keyword(s): stars: activity - (stars:) binaries: eclipsing - stars: coronae - stars: late type - stars: rotation - X-rays: stars

CDS comments: Several 1RXS J... do not exist in the RASS catalogue. Some are replaced by existing 1RXS, the others are renamed RX J...

Simbad objects: 122

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Number of rows : 122
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 V* AQ Tuc EB* 00 17 21.5138001102 -71 54 56.848760060   10.44 10.12     F3/5(+A) 60 0
2 V* CN And EB* 00 20 30.5420869255 +40 13 33.803422638   10.24 9.706     F5V 113 0
3 V* BH Cas EB* 00 21 21.3765858027 +59 09 05.413691241   13.26 12.77     K4V 47 0
4 V* V523 Cas EB* 00 40 06.2678868929 +50 14 15.516158313       10.405   K4V 156 0
5 V* CW Cas EB* 00 45 52.7049598333 +63 05 08.453600159   12.10 11.31     G8V 97 0
6 V* ER Cep EB* 00 50 27.6926266264 +85 15 08.487204979 17.145 16.635 15.809 15.175 14.804 ~ 57 0
7 V* AD Phe EB* 01 16 38.0705633402 -39 42 31.333170513   11.06 10.47     ~ 36 0
8 V* AQ Psc EB* 01 21 03.5556896246 +07 36 21.618400049   9.20 8.69   8.053 F8 57 0
9 V* AE Phe EB* 01 32 32.9321973079 -49 31 41.290852285   8.75 8.15     G4V 117 0
10 V* GW Cep EB* 01 45 58.6221078692 +80 04 55.325040324   11.72 11.21     G3 62 0
11 V* TW Cet EB* 01 48 54.1434549440 -20 53 34.595492634   11.25 10.61   9.787 G5+G8 87 0
12 V* VY Cet EB* 01 49 33.6922704694 -19 37 29.252171890   12.09 11.48 11.006   ~ 29 0
13 NGC 752 OpC 01 57 41 +37 47.1           ~ 565 0
14 V* QX And EB* 01 57 57.7817802186 +37 48 22.450045733   11.91 11.43 11.23   F5 99 0
15 V* SS Ari EB* 02 04 18.4070835062 +24 00 02.292158581   11.00 10.15     G0 106 0
16 V* UX Eri EB* 03 09 52.7437514915 -06 53 33.510267719   11.61 10.97     F9V 84 0
17 V* V524 Per BY* 03 18 58.6912098352 +48 50 42.354407877     13.609     K5 16 0
18 Cl Melotte 20 OpC 03 26 42 +48 48.0           ~ 778 0
19 V* GK Per No* 03 31 12.0096626899 +43 54 15.467450081   14.139 13.090 12.589   K1IV 879 0
20 Cl Melotte 22 OpC 03 47 00 +24 07.0           ~ 3104 0
21 V* BV Eri EB* 03 51 53.3423789055 -10 31 49.466329635   8.69       F2V 51 0
22 V* RU Eri EB* 03 54 43.7742877243 -14 56 06.649923251   9.86 9.39     F3V 42 0
23 V* YY Eri EB* 04 12 08.8494411846 -10 28 09.993813939   9.08 8.41   7.673 G3/K0+(F/G) 208 0
24 V* SY Hor EB* 04 14 18.3595269051 -46 26 57.110128490   11.96 11.36 11.114 10.251 ~ 19 0
25 V* AO Cam EB* 04 28 13.6470237835 +53 02 44.465212969   11.23 10.51     G0V 92 0
26 V* RZ Tau EB* 04 36 37.6612742555 +18 45 17.794204502   10.79 10.19     F5 136 0
27 V* UZ Oct EB* 04 43 35.9619560492 -84 48 39.925541263   9.72 9.21     ~ 32 0
28 V* AP Dor EB* 05 06 45.0919973349 -59 03 03.455782184   9.76 9.37     F5V 30 0
29 V* ER Ori EB* 05 11 14.5046439527 -08 33 24.601331471   10.02 9.46     G1V: 172 0
30 V* RS Col Ce* 05 15 31.2444185062 -28 45 02.127028814   10.27 9.67     G0V 42 0
31 V* RW Dor EB* 05 18 32.5454675242 -68 13 32.777407023   11.85 11.16 8.66 10.111 G4/5V 76 0
32 V* TY Men RR* 05 26 49.7267905252 -81 35 07.207190402   8.51 8.26   7.913 A3/4V 60 0
33 V* V781 Tau EB* 05 50 13.1257943382 +26 57 43.362139205   9.28 8.67   7.976 G0 100 0
34 V* TY Pup EB* 07 32 46.2312584822 -20 47 31.076324950   8.99 8.60     F3V 80 0
35 V* HI Pup EB* 07 33 38.2099558859 -50 07 25.042300452   11.09 10.54     ~ 27 0
36 V* FG Hya EB* 08 27 03.9413981176 +03 30 52.329514882   10.62 10.04   9.401 G0 177 0
37 V* TX Cnc EB* 08 40 01.7039481625 +18 59 59.422657649   10.71 9.97 9.88   G0-G1V 211 0
38 V* BU Vel EB* 08 40 06.2923988882 -42 49 43.378848085   11.08 10.78     F0 32 0
39 NGC 2632 OpC 08 40 24 +19 40.0           ~ 1317 0
40 IC 2391 OpC 08 40 32 -53 02.0           ~ 741 0
41 V* AD Cnc EB* 08 46 20.1002033642 +10 20 07.363744039   13.80 13.06     K0V 84 0
42 NGC 2682 OpC 08 51 18 +11 48.0           ~ 2109 0
43 Cl* NGC 2682 SAND 1036 EB* 08 51 28.1469824237 +11 49 27.498107329 13.262 13.27 12.809   12.184 F3 68 0
44 Cl* NGC 2682 SAND 1282 EB* 08 51 37.8473687335 +11 50 57.092630015 13.964 13.89 13.333   12.634 F7V 146 0
45 V* DF Hya EB* 08 55 02.2431734260 +06 05 37.587085714   11.45 10.80     G0 62 0
46 V* UV Lyn EB* 09 03 24.1260387911 +38 05 54.597326087   10.23 9.56     G0 95 0
47 V* S Ant EB* 09 32 18.3865325173 -28 37 39.967890838   6.77 6.45     F3V 131 0
48 V* W UMa EB* 09 43 45.4704899627 +55 57 09.066718574   8.54 7.75     G2Vn 639 1
49 V* AA UMa EB* 09 46 59.2851785172 +45 45 56.389509471   11.48 11.71     G0 74 0
50 V* RT LMi EB* 09 49 48.3190737270 +34 27 15.425664421   12.11 11.35 10.99   F7V 64 0
51 V* XY Leo EB* 10 01 40.4149118298 +17 24 32.578710513   10.66 9.68   8.474 K0V 264 0
52 V* XZ Leo EB* 10 02 34.1961100316 +17 02 47.142539645   10.79 10.37     A5 94 0
53 V* Y Sex EB* 10 02 47.9689716565 +01 05 40.183887562   10.38 9.95 9.875   F3/5V 103 0
54 V* UZ Leo EB* 10 40 33.1851453182 +13 34 00.856206822   10.13 9.75     F2 129 0
55 IC 2602 OpC 10 42 58 -64 24.0           ~ 581 0
56 V* AM Leo EB* 11 02 10.8845725849 +09 53 42.658542812   9.86 9.33   8.417 F8Vn 182 0
57 V* AP Leo EB* 11 05 05.0210506008 +05 09 06.407478312   10.07 9.57   8.849 F8V 115 0
58 V* AW UMa EB* 11 30 04.3159101276 +29 57 52.677255375   7.27   6.7   F0 275 1
59 V* TV Mus EB* 11 39 57.7650431238 -64 48 59.218089690   11.48 10.75   9.712 F2 65 0
60 V* V752 Cen EB* 11 42 48.0813388953 -35 48 57.503249188   9.88 9.30 9.697   F7/G0(V) 74 0
61 V* CE Leo EB* 11 44 24.2553681651 +23 21 22.850397594     12.39     K 84 0
62 V* AG Vir EB* 12 01 03.5038236924 +13 00 30.018273805   8.78 8.52     A7V 154 0
63 V* EH Hya EB* 12 04 50.9662614249 -33 09 22.466907843     14.33     ~ 17 0
64 V* W Crv EB* 12 07 34.3572506786 -13 08 59.016512619   11.95 11.28     ~ 73 0
65 V* TY UMa EB* 12 09 02.4999496149 +56 01 53.953473867   12.42 11.59     F8+F0 76 0
66 V* CC Com EB* 12 12 06.0377635998 +22 31 58.684494436   13.09 11.42   10.085 K4/5V 199 0
67 HD 106400 EB* 12 14 20.99618 +11 49 09.3870   9.94 9.22 9.37 8.390 G8V 218 0
68 V* RW Com EB* 12 33 00.2841958714 +26 42 58.362399221   12.33 11.682 10.929   G8e 147 0
69 V* RZ Com EB* 12 35 05.0595716847 +23 20 14.030368274   11.09 10.57     G0Vn 182 0
70 V* RV Crv EB* 12 37 40.7106798062 -19 34 40.034437690   9.13 8.76     F0V 63 0
71 V* SX Crv EB* 12 40 15.0428795155 -18 48 00.939139142   9.56 9.108   8.412 F7V 79 0
72 V* BI CVn EB* 13 03 16.4093211549 +36 37 00.645296050   10.99 10.31     F9V 85 0
73 V* XY Boo EB* 13 49 11.5668982802 +20 11 24.591106089   10.71 10.54     F5V 139 0
74 HD 120734 EB* 13 51 55.7389560858 -36 37 24.833755638   9.13 8.54   7.771 G0V+G0V 66 0
75 V* TU Boo EB* 14 04 58.0475314650 +30 00 01.588837705   12.22 11.61 12.09   G3 71 0
76 V* V759 Cen EB* 14 10 41.2606316489 -47 46 08.388230489   8.11 7.54     G0V 55 0
77 V* RR Cen EB* 14 16 57.2205732062 -57 51 15.655885175 7.70 7.65 7.29     A9/F0V 139 0
78 V* VW Boo EB* 14 17 26.0324383137 +12 34 03.449790911   11.33 10.55   9.777 G5 104 0
79 V* CK Boo EB* 14 35 03.7594697546 +09 06 49.375637476   9.61 9.029   8.414 F7/8V 126 0
80 V* V677 Cen EB* 14 42 34.6428635653 -40 27 16.018950525   11.47 10.85   10.00 ~ 26 0
81 V* GR Vir EB* 14 45 20.2633088053 -06 44 04.130465519   8.54 8.00   7.34 G2/3V 126 0
82 V* AC Boo EB* 14 56 28.3365272776 +46 21 44.072652819   10.74 10.23     F8Vn 121 0
83 V* TY Boo EB* 15 00 46.9394774048 +35 07 54.743547575   12.03 11.39 11.38   G3+G7 124 0
84 * i Boo EB* 15 03 47.29565 +47 39 14.6228           G0Vn 527 0
85 * i Boo B SB* 15 03 47.5145615709 +47 39 16.128926807   6.82 6.004     G9: 54 1
86 V* TZ Boo EB* 15 08 09.1344964536 +39 58 12.864002715   10.60       G2Vn 195 0
87 V* BW Dra EB* 15 11 50.0992475613 +61 51 41.230539303   9.39   8.3   B0 121 0
88 V* BV Dra EB* 15 11 50.3595172449 +61 51 25.282913496   8.54   7.7   F9V+F8V 149 2
89 V* AU Ser EB* 15 56 49.4688123911 +22 16 01.590194012   11.76 11.04 10.93   G4V 95 0
90 V* CM Dra BY* 16 34 20.3299130309 +57 09 44.365524588   14.50 12.87 10.85 9.26 M4.5V 412 0
91 V* V502 Oph EB* 16 41 20.8609964438 +00 30 27.383882425   9.15 8.50   7.865 G2V+F9V 179 0
92 V* AK Her EB* 17 13 57.8235712254 +16 21 00.617382214   9.04 8.51   7.874 F8Vv 251 0
93 V* V535 Ara EB* 17 38 05.5503137405 -56 49 17.291674231   7.69 7.36     A8V 90 0
94 V* V566 Oph EB* 17 56 52.4104254187 +04 59 15.324800914   8.03 7.58     F5V 243 0
95 V* V508 Oph EB* 17 58 48.6178959241 +13 29 46.282169772   11.25 10.65     G5 103 0
96 OGLE BW3 V38 EB* 18 04 44.2034110073 -30 09 05.505472642     18.300   16.3335 ~ 39 0
97 V* FS CrA EB* 18 06 12.1976739073 -37 31 29.638446615           ~ 16 0
98 V* V839 Oph EB* 18 09 21.2653297696 +09 09 03.605427060   9.62 9.03   8.286 F8V 134 0
99 V* FG Sct EB* 18 45 03.6522533220 -06 06 15.514973295           ~ 24 0
100 * eps CrA EB* 18 58 43.3840785329 -37 06 26.377252402   5.19 4.83     F4VFe-0.8+ 196 0
101 V* V803 Aql EB* 19 00 44.1854268626 -07 28 53.972949617           ~ 33 0
102 V* OO Aql EB* 19 48 12.6527583988 +09 18 32.374120037   10.26 9.49   8.762 G5V 218 1
103 V* CV Cyg EB* 19 54 20.9059486857 +38 02 49.972219764     10.85 10.60 10.320 F8III 58 0
104 V* V700 Cyg EB* 20 31 05.2475490142 +38 47 00.458769161   12.36 11.14     G2V 62 0
105 V* ST Ind EB* 20 35 23.8073509083 -48 19 19.783723134   11.83 11.12     ~ 17 0
106 V* VW Cep EB* 20 37 21.6248469581 +75 36 01.889162699   8.13   7.0   G8V+K0V 528 0
107 V* MW Pav EB* 20 46 27.7482468407 -71 56 58.465629949   9.15 8.79     F3IV/V 65 0
108 V* LS Del EB* 20 57 10.2862992640 +19 38 59.243423876   9.178 8.722 8.3 8.054 G5 66 0
109 V* BI Vul EB* 21 22 48.0350460134 +27 01 39.845571725           ~ 46 0
110 V* V1073 Cyg EB* 21 25 00.3572317438 +33 41 14.937113872   8.78 8.38     A1VpSi: 133 0
111 V* DK Cyg EB* 21 35 02.6694770300 +34 35 45.398785963   10.98 10.56     A6V 132 0
112 V* BX Peg EB* 21 38 49.3905754055 +26 41 34.205957391     10.890     G4.5 130 0
113 V* RW PsA EB* 22 09 46.9306309253 -27 04 01.518519563   11.93 11.16     ~ 34 0
114 V* BB Peg EB* 22 22 56.8918060653 +16 19 27.858385096   11.69 11.17     F8V 109 0
115 V* EM Lac EB* 22 23 54.7819593951 +54 01 09.270291922   12.20       ~ 39 0
116 V* SW Lac EB* 22 53 41.6541327083 +37 56 18.604271966   9.65 8.51     K0Vv 354 0
117 V* AB And EB* 23 11 32.0860884375 +36 53 35.107206154   10.62 9.50     G5+G5V 255 0
118 V* WZ Cep EB* 23 22 24.1932513922 +72 54 56.832888411   11.97 11.48     F5 67 0
119 V* VZ Psc EB* 23 27 48.3882787476 +04 51 23.935673863   11.39 10.274 10.090 8.926 K4/5V 104 0
120 V* BK And RR* 23 35 06.0326911269 +41 06 10.470713506   12.20 12.88     ~ 33 0
121 V* EL Aqr EB* 23 47 18.3455361182 -08 05 12.097350816   10.91 10.41     F 37 0
122 V* U Peg EB* 23 57 58.4767547238 +15 57 10.083936262   10.26 9.63   8.970 G2V 237 0

    Equat.    Gal    SGal    Ecl

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2021.07.28-14:08:05

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