2001MNRAS.326.1391M


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.06CEST01:18:33

2001MNRAS.326.1391M - Mon. Not. R. Astron. Soc., 326, 1391-1402 (2001/October-1)

The binary fraction of extreme horizontal branch stars.

MAXTED P.F.L., HEBER U., MARSH T.R. and NORTH R.C.

Abstract (from CDS):

We have used precise radial velocity measurements of subdwarf-B stars from the Palomar-Green catalogue to look for binary extreme horizontal branch (EHB) stars. We have determined the effective temperature, surface gravity and surface helium abundance for 20 of the targets from new or existing blue spectra and have compiled published values for these quantities for all but one other. We identify 36 EHB stars in our sample and find that at least 21 of these stars are binaries. All but one or two of these are new identifications. The minimum binary fraction for EHB stars implied by our survey is 60±8 per cent. Our survey is sensitive to binaries with orbital periods P≲10d. For reasonable assumptions concerning the period distribution and the mass ratio distribution of the binaries, we find that the mean detection efficiency of our survey over this range of orbital periods is 87 per cent. Allowing for this estimated detection efficiency, the fraction of EHB stars that are short-period binaries (0.03d≲P≲10d) is 69±9 per cent. The value is not strongly dependent on the period distribution below P~10d or the mean companion mass for these short-period binaries. The orbital separation of the stars in these binaries is much less than the size of the red giant from which the EHB star has formed. This is strong evidence that binary star evolution is fundamental to the formation of the majority of EHB stars. If there are also binary EHB stars, the orbital periods of which are ≳10d, the fraction of EHB stars for which evolution was affected by the presence of a companion may be much higher, e.g. if one third of EHB stars are binaries with orbital periods 10d≲P≲100d, then our observations are consistent with all EHB stars being formed through some type of binary star evolution. We find that five of the other stars we observed are likely to be post-EHB stars, one of which is also a binary.

Abstract Copyright: 2001 Blackwell Science Ltd

Journal keyword(s): binaries: close - binaries: spectroscopic - subdwarfs

Simbad objects: 54

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Number of rows : 54

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 Feige 11 HS* 01 04 21.6744758331 +04 13 37.051396308 10.847 11.826 12.065 12.183 12.324 sdB2VIHe4 114 0
2 V* IQ Cam HS* 04 26 06.8650071405 +54 28 17.100742176 14.21 14.86 14.66     sdB 58 0
3 PG 0749+658 HS* 07 54 24.4159207511 +65 42 07.370276463   12.07 12.06 12.29   sdB 28 0
4 PG 0839+399 HS* 08 43 12.7071071970 +39 44 49.809690592 12.918 14.045 14.324 14.445 14.587 sdB 35 0
5 Ton 358 HS* 08 52 54.6285015049 +31 43 36.648355745   14.29 14.59 14.78   sdOA 18 0
6 PG 0850+170 HS* 08 53 23.6574532327 +16 49 35.267448975   13.72 14.00 14.26   sdB 26 0
7 PG 0907+123 HS* 09 10 25.4345104999 +12 08 27.079359194   13.76 13.92 14.19   sdB2VIHe2 27 0
8 PG 0909+164 HS* 09 12 07.2920221180 +16 13 20.452538513   13.88 13.851     sdO8VIIHe1 17 0
9 PG 0918+029 HS* 09 21 28.2141418281 +02 46 02.253964445 11.975 13.056 13.327 13.456 13.615 sdB1VIIHe6 103 0
10 Ton 13 HS* 09 22 39.8342560495 +27 02 25.427174461   12.27 12.658     sdB 31 0
11 PG 0940+068 WD* 09 42 55.0397535559 +06 35 37.185711341   13.50 13.69 14.01   DA2: 23 0
12 PG 1000+408 HS* 10 03 54.2700940565 +40 34 18.121525685 11.919 12.988 13.318 13.465 13.631 sdO 27 0
13 V* XY Sex HS* 10 20 14.4717584584 -08 53 46.404001164   14.46 14.43     sdB 34 0
14 PG 1018-047 HS* 10 21 10.5823526588 -04 56 19.571214420   13.143 13.311     sdB2VIIHe0 25 0
15 PG 1032+406 HS* 10 35 16.5804303572 +40 21 14.420356201   11.38 11.81     sdB 36 0
16 Ton 1273 HS* 10 41 52.6983050843 +21 40 32.822907437     13.15     sdB 12 0
17 Ton 1281 HS* 10 43 39.3541101586 +23 09 06.261615751   13.05 13.371     sdB+G1V 16 0
18 PG 1043+760 HS* 10 47 04.9686856449 +75 44 22.970014499   12.97       sdB 23 0
19 V* UY Sex HS* 10 50 02.8264873492 -00 00 36.880346331 12.063 13.184 13.474 13.606 13.769 sdO9VIIHe6 151 0
20 PG 1051+501 HS* 10 54 18.5258344379 +49 49 59.717354047   13.30 13.59 13.70   sdB 19 0
21 Feige 36 HS* 11 04 31.6441819696 +24 39 42.691859421   12.87 12.78     sdB 51 0
22 Ton 62 HS* 11 13 04.4869938454 +29 07 46.226753961   14.2 14.086     sdB 21 0
23 Feige 38 HS* 11 16 49.3629050435 +06 59 33.210041257   12.77 13.03     sdB1.5VIIHe3 34 1
24 Ton 63 HS* 11 19 04.8239898746 +29 51 52.663724259   14.11 14.37 14.61   sdB 28 0
25 Ton 97 HS* 12 39 39.4142818012 +12 57 37.756623115   14.6       sdB 13 0
26 BD-07 3477 HS* 12 44 20.2386520980 -08 40 16.848587212   10.46 10.594 10.895   sdB2VIIHe3 258 1
27 PG 1244+113 HS* 12 47 06.6308614182 +11 03 13.361194734   13.05       sdB 22 0
28 GD 319 SB* 12 50 04.5262298 +55 06 01.800186   12.40 12.26 12.15   sdB+? 72 0
29 PG 1248+164 HS* 12 50 50.2676038282 +16 10 03.168524469   14.40 14.460     sdB 20 0
30 LB 27 HS* 13 02 41.7576687260 +27 40 42.172544649   12.93 11.97     sdO6.5VIIpHe35 37 1
31 PG 1303+097 HS* 13 06 03.8835174426 +09 24 31.271677125   14.34       sdB 14 0
32 Feige 81 HS* 13 31 53.5518978105 +15 41 17.571717155   13.24 13.507     sdBpec 40 0
33 V* NY Vir HS* 13 38 48.1466489725 -02 01 49.209465866   13.43 13.66 13.75   sdB1VIIHe1 198 1
34 Ton 194 HS* 14 20 07.4190255475 +25 29 18.605878700   13.49 13.68     sdB 13 0
35 PG 1432+159 HS* 14 35 18.9439672422 +15 40 14.372230565   13.63       sdB 28 1
36 PG 1505+074 HS* 15 08 21.0454785177 +07 13 14.849365277   12.00 11.92 12.95   sdB 14 0
37 Ton 788 HS* 15 14 32.4560596705 +24 10 40.704992828   13.03 13.21     sdB 27 0
38 Ton 245 HS* 15 40 23.4584728304 +26 48 29.782790077   13.65 13.83     sdB 40 0
39 PG 1553+273 HS* 15 55 37.8563725215 +27 06 48.465885123   13.53 13.530     sdB 12 1
40 PG 1616+144 HS* 16 18 23.0938143530 +14 16 12.893198340   13.48       sdB 15 0
41 PG 1619+522 HS* 16 20 38.7298845239 +52 06 08.805926996   13.36       sdB0.5VIIHe7 29 0
42 PG 1627+017 HS* 16 29 35.3015296881 +01 38 18.794470062   11.32       sdB3VIIHe3 40 0
43 Ton 817 HS* 16 33 49.3296687814 +26 32 58.610307068     15.40     sdB+G 10 1
44 PG 1632+088 HS* 16 34 47.0436803419 +08 40 00.061296950   13.17 13.21 13.46   sdBpec 9 0
45 PG 1647+056 HS* 16 50 18.4607797389 +05 32 56.019070381 13.536 14.600 14.773 14.831 14.855 sdB 13 0
46 PG 1653+131 HS* 16 55 42.8182039082 +13 01 48.514204368   14.18 14.42 14.57   sdB 13 0
47 PG 1701+359 HS* 17 03 21.4566267727 +35 48 49.249634670   13.41       sdB1VIHe0 30 0
48 PG 1710+490 HS* 17 12 18.7559887923 +48 58 35.783945756   12.56 13.03     sdB1.5VIIHe3 31 0
49 PG 1716+426 HS* 17 18 03.8584285848 +42 34 12.566188858   13.69 13.97     sdB2VIIHe3 99 0
50 PG 1722+286 HS* 17 24 11.9613344807 +28 35 26.863845671   13.20 13.19 13.92   sdB0VIIpHe10 18 0
51 PG 1725+252 HS* 17 27 57.3822581233 +25 08 35.694002450   11.54 13.01     sdB1.5VIIHe2 23 0
52 PG 1743+477 HS* 17 44 26.3960105328 +47 41 46.919987620   13.68 13.79 13.99   sdB2VIIHe7 28 0
53 KPD 1930+2752 HS* 19 32 14.8086352823 +27 58 35.444970697 12.80 13.75 13.82     sdB 146 0
54 PG 2345+318 HS* 23 48 07.5062970948 +32 04 48.037660206   13.99 14.19 14.66   sdB 27 0

    Equat.    Gal    SGal    Ecl

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2021.05.06-01:18:33

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