2009ApJ...698.1330P


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.25CET07:38:39

2009ApJ...698.1330P - Astrophys. J., 698, 1330-1340 (2009/June-3)

Runaway and hypervelocity stars in the galactic halo: binary rejuvenation and triple disruption.

PERETS H.B.

Abstract (from CDS):

Young stars observed in the distant Galactic halo are usually thought to have formed elsewhere, either in the Galactic disk or perhaps the Galactic center (GC), and subsequently ejected at high velocities to their current position. However, some of these stars have apparent lifetimes shorter than the required flight time from the Galactic disk/GC. We suggest that such stars have evolved in close runaway or hypervelocity binaries. Stellar evolution of such binaries can drive them into mass transfer configurations and even mergers. Such evolution could then rejuvenate them (e.g., blue stragglers) and extend their lifetime after their ejection. The extended lifetimes of such stars could then be reconciled with their flight times to the Galactic halo. We study the possibilities of binary runaway and hypervelocity stars (HVSs) and show that such binaries could have been ejected in triple disruptions and other dynamical interactions with stars or with massive black holes (MBHs). We show that currently observed "too young" star in the halo could have been ejected from the Galactic disk or the GC and be observable in their current position if they were ejected as binaries. Specifically, it is shown that the HVS HE 0437-5439 could be such a rejuvenated star. Other suggestions for its ejection from the Large Magellanic Cloud are found to be highly unlikely. Moreover, it is shown that its observed metallicity is most consistent with a Galactic origin and a GC origin cannot currently be ruled out. In addition, we suggest that triple disruptions by the MBH in the GC could also capture binaries in close orbits near the MBH, some of which may later evolve to become more massive rejuvenated stars.

Abstract Copyright:

Journal keyword(s): black hole physics - galaxies: nuclei - stars: kinematics

Simbad objects: 21

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Number of rows : 21

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 CD-37 316 Be* 00 53 01.6835345046 -36 20 20.686616662   12.30 12.39 12.75   B2p(e) 24 0
2 PG 0122+214 * 01 25 29.5981965945 +21 36 30.682732901   12.60 13.34     sd 17 0
3 HE 0437-5439 HS* 04 38 12.7828185490 -54 33 11.840105637 15.37 16.18 16.42     sdB+F 63 0
4 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15050 1
5 PG 0914+001 HS* 09 17 12.2423302371 -00 08 38.460002371   14.43 14.53 14.62   sdB 15 0
6 US 708 HS* 09 33 20.8630614743 +44 17 05.503100302   18.5 18.8     sdOHe 72 0
7 BD+38 2182 * 10 49 12.9128829570 +38 00 14.848115941   10.95 11.2     B3V 50 0
8 PG 1209+263 HB* 12 12 13.3437496767 +26 00 00.035466665   14.62 14.59     B 11 0
9 BD+36 2268 V* 12 25 23.4489545720 +35 58 33.473861116   10.20 10.31     B3Vn 47 0
10 HD 140543 * 15 44 56.6611847490 -21 48 53.908555222 7.97 8.86 8.88     B1Iab/b(n) 48 0
11 LB 9514 WD* 16 13 01.5329521515 +23 48 30.812862029   12.70 14.67 16.14   DB4 27 0
12 GCIRS 7 * 17 45 39.987 -29 00 22.24           M2 348 0
13 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11820 0
14 GCIRS 8 * 17 45 40.14 -28 59 58.7           O 71 0
15 HS 1914+7139 * 19 14 10.0915266502 +71 44 39.979489146     14.5     B2.5IV 11 0
16 HD 188618 * 19 56 40.4817339625 -17 55 17.060054976   9.48 9.38     B2II 22 0
17 HD 206144 * 21 40 33.3795495512 -17 36 00.557914712 8.36 9.22 9.34     B2II(n) 57 0
18 PHL 159 * 21 48 44.2701173420 +01 57 33.824984124   10.67 10.84     ~ 14 0
19 PG 2219+094 HS* 22 21 59.1664271264 +09 37 25.733927625   11.78 12.06     sdB0.5VpHe7 29 0
20 PG 2229+099 HS* 22 32 08.7224640826 +10 14 25.116846249   13.19 13.28 13.42   sdB5IIIHe11 15 0
21 V* HN Aqr bC* 22 37 38.2846197264 -18 39 51.268673991   11.28 11.47     B 58 0

    Equat.    Gal    SGal    Ecl

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2020.11.25-07:38:39

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