A hypervelocity star from the Large Magellanic Cloud

作者：Gualandris Alessia^*; Portegies Zwart Simon

来源：Monthly Notices of the Royal Astronomical Society, 2007, 376(1): L29-L33.

DOI：10.1111/j.1745-3933.2007.00280.x

• black hole physics
• stellar dynamics
• methods : N-body simulations
• binaries : general
• stars : individual : HE 0437-5439

We study the acceleration of the star HE 0437-5439 to hypervelocity and discuss its possible origin in the Large Magellanic Cloud (LMC). The star has a radial velocity of 723 km s(-1) and is located at a distance of 61 kpc from the Sun. With a mass of about 8 M-circle dot, the traveltime from the Galactic Centre is about 100 Myr, much longer than its main-sequence lifetime. Given the relatively small distance to the LMC (18 kpc), we consider it likely that HE0437-5439 originated in the Cloud rather than in the Galactic Centre like the other hypervelocity stars. The minimum ejection velocity required to travel from the LMC to its current location within its lifetime is about 500 km s(-1). Such a high velocity can only be obtained in a dynamical encounter with a massive black hole. We perform three-body scattering simulations in which a stellar binary encounters a massive black hole, and find that a black hole more massive than 10(3) M-circle dot is necessary to explain the high velocity of HE0437-5439. We look for possible parent clusters for HE0437-5439, and find that NGC2100 and 2004 are young enough to host stars coeval to HE 0437-5439 and dense enough to produce an intermediate-mass black hole able to eject an 8-M-circle dot star with hypervelocity.

• 出版日期2007-3-21