1997A&A...327..577D


Query : 1997A&A...327..577D

1997A&A...327..577D - Astronomy and Astrophysics, volume 327, 577-586 (1997/11-2)

Hot subdwarf stars: galactic orbits and distribution perpendicular to the plane.

DE BOER K.S., AGUILAR SANCHEZ Y., ALTMANN M., GEFFERT M., ODENKIRCHEN M., SCHMIDT J.H.K. and COLIN J.

Abstract (from CDS):

The spatial distribution and the population nature of subdwarf B type stars in the galaxy is investigated based on the kinematics of these stars. With new and available proper motions, radial velocities, and distances, the orbits of 41 stars have been calculated using a galactic mass model. The orbits are well behaved and 10 stars reach to |z|≥2kpc. Many orbits are very eccentric, reaching in to just 2kpc from the galactic centre, or veering out to beyond 20kpc. None of the stars can be identified uniquely as classical Population II objects. The average eccentricity ecc of the orbits of our sample is 0.24, the average normalised z-extent nze of the orbits is 0.16, and the asymmetric drift of our sample is -36km/s. This suggests that our sample of sdB stars is part of a population of thick disk stars. A statistical analysis of the orbits shows that the subdwarf stars have a spatial distribution in z compatible with an exponential one with a scale height hz of about 1.0kpc. However, since only few stars reach to large z the spatial distribution is only well defined to z ≃2kpc. The distribution in z shows a relative minimum near z=0pc and has maxima near z=300pc. This reflects the smaller probability to find the stars in the disk than away from the disk, as expected for any orbit reaching to larger z. Scale height studies based on limited samples of stars in specified directions can therefore easily be flawed when they do not reach to large enough distances to overcome this aspect of the z-distribution.

Abstract Copyright:

Journal keyword(s): astrometry - stars: kinematics - stars: horizontal branch - stars: Population II - Galaxy: halo - Galaxy: structure

Simbad objects: 41

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Number of rows : 41
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 PG 2358+107 HS* 00 01 06.7296663432 +11 00 36.323514252   13.51 13.59 13.89   sdB2VIIHe4 16 0
2 PG 0004+133 HS* 00 07 33.7731772800 +13 35 57.590895264   12.63 13.02     sdB2.5VHe7 25 0
3 PG 0039+049 HS* 00 42 06.1225924704 +05 09 23.394042396 11.987 12.858 12.877 12.810 12.713 sdB+G2V 31 0
4 CD-38 222 HS* 00 42 58.3063027488 -38 07 37.291406772   10.19 10.26     sdB 53 0
5 Feige 11 HS* 01 04 21.6747168600 +04 13 37.054495956 10.847 11.826 12.065 12.183 12.324 sdB2VIHe4 116 0
6 PG 0133+114 HS* 01 36 26.1919824456 +11 39 32.100292692   10.74       sdB1.5VIIHe4 36 0
7 PHL 1079 HS* 01 38 26.9920350720 +03 39 39.089787300   12.4 12.6     sdB+G7V 18 0
8 PG 0142+148 HS* 01 45 39.5157944208 +15 04 42.178208916   12.02       sdB2VIHe2 16 0
9 PG 0212+148 HS* 02 15 11.1018783504 +15 00 04.174598268   13.71       sdB 15 0
10 PG 0212+143 HS* 02 15 41.6661943464 +14 29 18.034926864   14.45 14.59 14.80   sdB 13 0
11 PG 0242+132 HS* 02 45 38.8794857304 +13 25 55.644358152   11.78       sdB0.5VHe10 21 0
12 V* HK Cnc HS* 08 59 02.6445309720 +11 56 27.841260300   13.47 13.480     sdB3VIIHe0 31 0
13 PG 0907+123 HS* 09 10 25.4347130256 +12 08 27.078221868   13.76 13.92 14.19   sdB2VIHe2 28 0
14 PG 0918+029 HS* 09 21 28.2138172968 +02 46 02.254084824 11.975 13.056 13.327 13.456 13.615 sdB1VIIHe6 105 0
15 Ton 13 HS* 09 22 39.8341061496 +27 02 25.424125980   12.27 12.658     sdB 31 0
16 Feige 36 HS* 11 04 31.6443383808 +24 39 42.687580896   12.87 12.78     sdB 51 0
17 Feige 38 HS* 11 16 49.3630906272 +06 59 33.203109948   12.77 13.03     sdB1.5VIIHe3 34 1
18 PG 1232-136 HS* 12 35 18.7430526168 -13 55 08.879064096   13.06 13.27     sdB 25 0
19 Feige 65 HS* 12 35 51.1437498960 +42 22 39.720230508   11.78 12.046     sdB2 62 1
20 HZ 38 HS* 12 59 21.2509327032 +27 34 06.043023804   13.9       sdOA 32 0
21 PG 1343-102 HS* 13 46 07.9748014416 -10 26 48.487760412   13.46 13.73     sdB1.5VIIHe0 13 1
22 PG 1432+004 HS* 14 35 19.8406916232 +00 13 51.115007964   12.20 12.39     sdB2VIIHe6 27 0
23 Ton 209 HS* 14 35 20.2387953384 +23 45 30.479195592   12.20 12.11 12.86   sdB2VIIHe4 22 0
24 PG 1452+198 HS* 14 54 39.8152055328 +19 37 00.855649740   12.30 12.94     sdB0.5VIIIHe7 18 0
25 PG 1519+640 HS* 15 20 31.3676002152 +63 52 08.251179924   12.03 12.18     sdB1.5VIIHe5 35 0
26 PG 1619+522 HS* 16 20 38.7296260680 +52 06 08.805043260   13.36       sdB0.5VIIHe7 29 0
27 Ton 264 HS* 16 49 08.9589473112 +25 10 06.234264948   14.04 14.09     sdOB 24 0
28 PG 1708+602 HS* 17 09 15.8897801784 +60 10 11.008596936   13.42 13.74 14.06   sdO2VIIHe14 36 0
29 PG 1710+490 HS* 17 12 18.7556895624 +48 58 35.782284900   12.56 13.03     sdB1.5VIIHe3 31 0
30 PG 1722+286 HS* 17 24 11.9612830536 +28 35 26.862921924   13.20 13.19 13.92   sdB0VIIpHe10 19 0
31 PG 1725+252 HS* 17 27 57.3822732240 +25 08 35.697468192   11.54 13.01     sdB1.5VIIHe2 23 0
32 PG 1738+505 HS* 17 39 28.4334887496 +50 29 25.105332624   13.12 13.21 13.46   sdB1.5VIIHe12 10 0
33 HD 205805 HS* 21 39 10.6154323536 -46 05 51.525534876 9.05 9.98 10.21     sdB 73 0
34 PG 2204+035 HS* 22 07 16.4981097216 +03 42 19.847765304   14.10 14.31 14.51   sdB1VIIHe10 19 1
35 PG 2218+020 HS* 22 21 24.8247732048 +02 16 18.431313708   13.6 13.9     sdB2.5VIIHe3 14 0
36 PG 2226+094 HS* 22 28 58.4823334800 +09 37 22.473322644   14.18 14.16 14.08   sdB 14 0
37 PG 2259+134 HS* 23 01 45.8247267744 +13 38 37.481529120   14.47 14.65 14.87   sdB1VIIHe9 22 0
38 Feige 108 HS* 23 16 12.4074790200 -01 50 35.103759540 11.671 12.736 12.973 13.079 13.218 sdB 63 0
39 Feige 109 HS* 23 17 26.8819938360 +07 52 04.910534364   13.87 13.92     sdB1.5VIIIpHe0 32 0
40 PG 2337+070 HS* 23 40 04.7469534912 +07 17 09.580462800   13.4 13.470 13.74   sdB1.5VIIHe9 17 0
41 PG 2349+002 HS* 23 51 53.2310316864 +00 28 17.655587688 12.165 13.086 13.277 13.380 13.496 sdB2VIIHe0 27 0

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2022.05.22-01:23:51

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