THE NATURE OF THE HYPER-RUNAWAY CANDIDATE HIP 60350

Journal Article · Mon Mar 01 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/711/1/138· OSTI ID:21394383

Irrgang, Andreas; Przybilla, Norbert; Heber, Ulrich ^[1]; Fernanda Nieva, M ^[2]; Schuh, Sonja ^[3]

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1. Dr. Karl Remeis Observatory and ECAP, University of Erlangen-Nuremberg, Sternwartstrasse 7, D-96049 Bamberg (Germany)
2. Max Planck Institute for Astrophysics, Karl-Schwarzschild-Strasse 1, D-85741 Garching (Germany)
3. Georg-August-Universitaet Goettingen, Institute for Astrophysics, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)

Young, massive stars in the Galactic halo are widely supposed to be the result of an ejection event from the Galactic disk forcing some stars to leave their place of birth as so-called runaway stars. Here, we present a detailed spectroscopic and kinematic analysis of the runaway B star HIP 60350 to determine which runaway scenario-a supernova explosion disrupting a binary system or dynamical interaction in star clusters-may be responsible for HIP 60350's peculiar orbit. Based on a non-local thermodynamic equilibrium approach, a high-resolution optical echelle spectrum was examined to revise spectroscopic quantities and for the first time to perform a differential chemical abundance analysis with respect to the B-type star 18 Peg. The results together with proper motions from the Hipparcos Catalog further allowed the three-dimensional kinematics of the star to be studied numerically. The abundances derived for HIP 60350 are consistent with a slightly supersolar metallicity agreeing with the kinematically predicted place of birth {approx}6 kpc away from the Galactic center. However, they do not exclude the possibility of an alpha-enhanced abundance pattern expected in the case of the supernova scenario. Its outstanding high Galactic rest-frame velocity of 530 +- 35 km s{sup -1} is a consequence of ejection in the direction of Galactic rotation and slightly exceeds the local Galactic escape velocity in a standard Galactic potential. Hence, HIP 60350 may be unbound to the Galaxy.

• OSTI ID: 21394383
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 711; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ATMOSPHERES
EXPLOSIONS
GALAXIES
MOTION
ORBITS
PROPER MOTION
ROTATION
STAR CLUSTERS
STARS
STELLAR ATMOSPHERES
VELOCITY