2008A&A...488L..51P


Query : 2008A&A...488L..51P

2008A&A...488L..51P - Astronomy and Astrophysics, volume 488, L51-54 (2008/9-3)

HVS7: a chemically peculiar hyper-velocity star.

PRZYBILLA N., NIEVA M.F., TILLICH A., HEBER U., BUTLER K. and BROWN W.R.

Abstract (from CDS):

Hyper-velocity stars are suggested to originate from the dynamical interaction of binary stars with the supermassive black hole in the Galactic centre (GC), which accelerates one component of the binary to beyond the Galactic escape velocity. The evolutionary status and GC origin of the hyper-velocity star SDSSJ113312.12+010824.9 (aka HVS7) is constrained from a detailed study of its stellar parameters and chemical composition. High-resolution spectra of HVS7 obtained with UVES on the ESO VLT were analysed using state-of-the-art NLTE/LTE modelling techniques that can account for a chemically-peculiar composition via opacity sampling. Instead of the expected slight enrichments of α-elements and near-solar iron, huge chemical peculiarities of all elements are apparent. The helium abundance is very low (<1/100 solar), C, N and O are below the detection limit, i.e they are underabundant (<1/100, ≲1/3 and <1/10 solar). Heavier elements, however, are overabundant: the iron group by a factor of ∼10, P, Co and Cl by factors ∼40, 80 and 440 and rare-earth elements and mercury even by ∼10000. An additional finding, relevant also for other chemically peculiar stars are the large NLTE effects on abundances of TiII and FeII (∼0.6-0.7dex). The derived abundance pattern of HVS7 is characteristic for the class of chemical peculiar magnetic B stars on the main sequence. The chemical composition and high projected rotation velocity v sin i=55±2km/s render a low mass nature of HVS7 as a blue horizontal branch star unlikely. Such a surface abundance pattern is caused by atomic diffusion in a possibly magnetically stabilised, non-convective atmosphere. Hence all chemical information on the star's place of birth and its evolution has been washed out. High precision astrometry is the only means to validate a GC origin for HVS7.

Abstract Copyright:

Journal keyword(s): Galaxy: halo - stars: abundances - stars: chemically peculiar - stars: distances - stars: early-type - stars: individual: SDSS J113312.12+010824.9

Simbad objects: 8

goto Full paper

goto View the references in ADS

Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 V* KZ Cam a2* 03 38 19.7334959304 +56 55 57.775389816 7.589 6.176 6.282     B9p 70 0
2 HE 0437-5439 HS* 04 38 12.7828168224 -54 33 11.834984736 15.37 16.18 16.42     sdB+F 72 0
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16411 1
4 HD 271791 HV* 06 02 27.8785167216 -66 47 28.695328404   12.17 12.28     B2(III) 62 0
5 LAWD 34 WD* 10 57 35.1341950895 -07 31 23.176779615 14.078 14.626 14.338 14.132 13.921 DC 76 0
6 SDSS J113312.12+010824.8 HS* 11 33 12.1225194672 +01 08 24.841717008   17.2 17.80 17.7   sdB 31 0
7 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13329 0
8 [EG97] S2 * 17 45 40.0442 -29 00 27.975           B0/2V 336 1

To bookmark this query, right click on this link: simbad:objects in 2008A&A...488L..51P and select 'bookmark this link' or equivalent in the popup menu


2022.12.07-05:29:00

© Université de Strasbourg/CNRS

    • Contact