Epoch J2000.0 Equinox J2000.0 (ICRS)
|Right ascension||09h 07m 44.99 s|
|Declination||+02° 45′ 06.9″|
SDSS J090744.99+024506.8 (SDSS 090745.0+024507), is a star that is leaving the Milky Way galaxy at twice the galactic escape velocity (0.002 the speed of light). In the past it was a double star system. The other star has fallen into a black hole and this star was greatly accelerated by the black hole. Christened by the astronomer Warren Brown as the Outcast Star, it is the first discovered member of a class of objects named hypervelocity stars.
The star is about 80 million years old, and as it contains many elements heavier than hydrogen and helium, having formed in the evolved star-forming regions of the galactic core, is considered metal-rich. It is moving directly away from the galactic center at over 1,500,000 miles per hour (2,400,000 km/h), twice as fast as the Milky Way's galactic escape velocity. Eventually the star will leave the galaxy completely.
- Berardelli, Phil (February 10, 2005), "In The Stars: Odd Stars, Odder Planets", Space Daily
- Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. & Kurtz, Michael J. (2005), "Discovery of an Unbound Hypervelocity Star in the Milky Way Halo", Astrophysical Journal 622 (1): L33–L36, arXiv:astro-ph/0501177, Bibcode:2005ApJ...622L..33B, doi:10.1086/429378
- Hills, J. G. (1988), "Hyper-velocity and tidal stars from binaries disrupted by a massive Galactic black hole", Nature 331 (6158): 687–689, Bibcode:1988Natur.331..687H, doi:10.1038/331687a0
- Gualandris, Alessia; Portegies Zwart, Simon & Sipior, Michael S. (2005), "Three-body encounters in the Galactic Centre: the origin of the hypervelocity star SDSS J090745.0+024507", Monthly Notices of the Royal Astronomical Society 363 (1): 223–228, arXiv:astro-ph/0507365, Bibcode:2005MNRAS.363..223G, doi:10.1111/j.1365-2966.2005.09433.x
- Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. & Kurtz, Michael J. (2006), "A Successful Targeted Search for Hypervelocity Stars", Astrophysical Journal 640 (1): L35–L38, arXiv:astro-ph/0601580, Bibcode:2006ApJ...640L..35B, doi:10.1086/503279
- Fuentes, Cesar I.; Stanek, K. Z.; Gaudi, B. Scott; et al. (2006), "The Hypervelocity Star SDSS J090745.0+024507 Is Variable", Astrophysical Journal 636 (1): L37–L40, arXiv:astro-ph/0507520, Bibcode:2006ApJ...636L..37F, doi:10.1086/499233
- Bromley, Benjamin C.; Kenyon, Scott J.; Geller, Margaret J.; et al. (2006), "Hypervelocity Stars: Predicting the Spectrum of Ejection Velocities", Astrophysical Journal 653 (2): 1194–1202, arXiv:astro-ph/0608159, Bibcode:2006ApJ...653.1194B, doi:10.1086/508419
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