Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-11-10
Astrophys.J.634:L181-L184,2005
Astronomy and Astrophysics
Astrophysics
13 pages, 4 figures. Astrophysical Journal Letters, accepted
Scientific paper
10.1086/498940
We report the discovery of a 16th magnitude star, HE0437-5439, with a heliocentric radial velocity of +723+-3km/s. A quantitative spectral analysis of high-resolution optical spectra obtained with the VLT and the UVES spectrograph shows that HE0437-5439 is a main sequence B-type star with Teff=20350K, log g=3.77, solar within a factor of a few helium abundance and metal content, rotating at v sin i=54km/s. Using appropriate evolutionary tracks we derive a mass of 8 Msun and a corresponding distance of 61 kpc. Its galactic rest frame velocity is at least 563km/s, almost twice the local Galactic escape velocity, indicating that the star is unbound to the Galaxy. Numerical kinematical experiments are carried out to constrain its place of birth. It has been suggested that such hyper-velocity stars can be formed by the tidal disruption of a binary through interaction with the super-massive black hole at the Galactic center (GC). HE0437-5439 needs about 100Myrs to travel from the GC to its presentposition, much longer than its main sequence lifetime of 25Myrs. This can only be reconciled if HE0437-5439 is a blue straggler star. In this case, the predicted proper motion is so small that it can only be measured by future space missions. Since the star is much closer to the Large Magellanic Cloud (LMC, 18kpc) than to the GC, it can reach its position from the center of the LMC. The proper motion predicted in this case is about 2mas/y (relative to the LMC), large enough to be measurable with conventional techniques from the ground. The LMC origin could also be tested by a high-precision abundance analysis.
Christlieb Norbert
Edelmann Heinz
Heber Uli
Napiwotzki Ralf
Reimers Dieter
No associations
LandOfFree
HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-385916