2019A&A...628L...5I


Query : 2019A&A...628L...5I

2019A&A...628L...5I - Astronomy and Astrophysics, volume 628, L5-5 (2019/8-1)

PG 1610+062: a runaway B star challenging classical ejection mechanisms.

IRRGANG A., GEIER S., HEBER U., KUPFER T. and FURST F.

Abstract (from CDS):

Hypervelocity stars are rare objects, mostly main-sequence (MS) B stars, traveling so fast that they will eventually escape from the Milky Way. Recently, it has been shown that the popular Hills mechanism, in which a binary system is disrupted via a close encounter with the supermassive black hole at the Galactic center, may not be their only ejection mechanism. The analyses of Gaia data ruled out a Galactic center origin for some of them, and instead indicated that they are extreme disk runaway stars ejected at velocities exceeding the predicted limits of classical scenarios (dynamical ejection from star clusters or binary supernova ejection). We present the discovery of a new extreme disk runaway star, PG 1610+062, which is a slowly pulsating B star bright enough to be studied in detail. A quantitative analysis of spectra taken with ESI at the Keck Observatory revealed that PG 1610+062 is a late B-type MS star of 4-5M with low projected rotational velocity. Abundances (C, N, O, Ne, Mg, Al, Si, S, Ar, and Fe) were derived differentially with respect to the normal B star HD 137366 and indicate that PG 1610+062 is somewhat metal rich. A kinematic analysis, based on our spectrophotometric distance (17.3kpc) and on proper motions from Gaia's second data release, shows that PG 1610+062 was probably ejected from the Carina-Sagittarius spiral arm at a velocity of 550±40km/s, which is beyond the classical limits. Accordingly, the star is in the top five of the most extreme MS disk runaway stars and is only the second among the five for which the chemical composition is known.

Abstract Copyright: © ESO 2019

Journal keyword(s): stars: abundances - stars: individual: HD 137366 - stars: kinematics and dynamics - stars: individual: PG 1610+062 - stars: early-type

CDS comments: Table 5 : B711, B434, B733, B485 are respectively SDSS J142001.94+124404.8, SDSS J110224.37+025002.8, SDSS J144955.58+310351.4 and SDSS J101018.82+302028.1 in SIMBAD (Irrgang et al. 2018A&A...615L...5I table 1)

Simbad objects: 25

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Number of rows : 25
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 HD 271791 HV* 06 02 27.8785167216 -66 47 28.695328404   12.17 12.28     B2(III) 69 0
2 LAMOST-HVS1 Em* 09 12 06.5238309096 +09 16 21.890911908   12.96 13.06     B1IV/V 19 0
3 PG 0914+001 HS* 09 17 12.2423039232 -00 08 38.458978440   14.43 14.53 14.62   sdB 18 0
4 [BGK2006] HV 5 HV* 09 17 59.4745317960 +67 22 38.377645896     17.70     B 20 0
5 [BGK2006] HV 8 HV* 09 42 14.0373776496 +20 03 22.048679124           B 16 0
6 Ton 30 HS* 10 10 18.8246436384 +30 20 28.168497816   16.02 15.96     sdB 27 0
7 [BGK2006] HV 12 HV* 10 50 09.5966400120 +03 15 50.619146796   20.2 19.76 19.8   sd 18 0
8 SDSS J110224.37+025002.8 HV* 11 02 24.3754875480 +02 50 02.872024728           A1 12 0
9 HD 100340 HS? 11 32 49.9414410936 +05 16 36.231905676 8.906 9.881 10.115 10.219 10.353 B0 100 0
10 SDSS J113312.12+010824.8 HS* 11 33 12.1225194672 +01 08 24.841717008   17.2 17.80 17.7   sdB 31 0
11 PG 1209+263 HB* 12 12 13.3438736640 +26 00 00.038105280   14.62 14.59     B 15 0
12 Feige 84 HS* 13 35 11.9823807408 +13 27 44.096137488   11.5 11.4     sdB3 43 0
13 HD 121968 * 13 58 51.1663111056 -02 54 52.325640252 9.160 10.071 10.256 10.330 10.429 B2II 108 0
14 SDSS J142001.94+124404.8 HV* 14 20 01.9366078920 +12 44 04.840195092           B9 9 0
15 SDSS J144955.58+310351.4 HV* 14 49 55.5761686536 +31 03 51.382720188           A1 12 0
16 HD 137366 * 15 30 49.1812877184 -71 39 14.886814896   6.27 6.38     B3V 19 0
17 PG 1610+062 HS* 16 12 53.2125160824 +06 05 38.796187560   15.52 15.55 15.79   sdB 10 0
18 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 14417 0
19 EC 19596-5356 HB* 20 03 29.9097537408 -53 48 07.176564612 13.66 14.25 14.37     B5 9 0
20 V* BR Mic bC* 21 27 01.1105727576 -31 56 20.496578820 7.8 8.64 8.73     B2II 54 1
21 V* HN Aqr bC* 22 37 38.2846689672 -18 39 51.268772880   11.293 11.426 11.813   B 67 0
22 PHL 2018 HS? 22 38 54.2170863600 -23 52 20.921305260   11.59 11.96     ~ 8 0
23 LAMOST-HVS4 HV* 22 58 37.5583345464 +40 00 05.413913136           ~ 6 0
24 HD 218970 PM* 23 12 30.6294754224 -21 06 43.453464732   9.57 9.81     A0p 42 0
25 PB 5418 * 23 30 49.0136397528 +05 26 01.993730064   11.88 11.35     B2He 11 0

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