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SDSS J090745.0+024507

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SDSS J090745.0+024507

SDSS image of SDSS J090745.0+024507 (blue dot in the center).
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 09h 07m 44.9925s[1]
Declination +02° 45′ 06.877″[1]
Apparent magnitude (V) 19.84[2]
Spectral type B9 V[3]
Variable type SPB[3]
Radial velocity (Rv)+853 ± 12[4] km/s
Distance230000 ly
(71000[3] pc)
Temperature10,500[3] K
Other designations
SDSS J090744.99+024506.8[5]
Database references

SDSS J090744.99+024506.8 (SDSS 090745.0+024507) is a short-period variable star in the constellation Hydra. It has a Galactic rest-frame radial velocity of 709 km/s.[3]

Its effective temperature is 10,500 K (corresponding to a spectral type of B9) and its age is estimated to be at most 350 million years. It has a heliocentric distance of 71 kpc. It was ejected from the centre of the galaxy less than 100 million years ago, which implies the existence of a population of young stars at the galactic centre less than 100 million years ago.[3]

Christened by the astronomer Warren Brown as the "outcast star", it is the first discovered member of a class of objects named hypervelocity stars.[6] It was discovered in 2005 at the MMT Observatory of the Center for Astrophysics | Harvard & Smithsonian (CfA), by astronomers Warren Brown, Margaret J. Geller, Scott J. Kenyon and Michael J. Kurtz.[4]

See also[edit]


  1. ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
  2. ^ Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.; Kurtz, Michael J.; Bromley, Benjamin C. (2007). "Hypervelocity Stars. III. The Space Density and Ejection History of Main-Sequence Stars from the Galactic Center". The Astrophysical Journal. 671 (2): 1708. arXiv:0709.1471. Bibcode:2007ApJ...671.1708B. doi:10.1086/523642. S2CID 15074398.
  3. ^ a b c d e f Cesar I. Fuentes; K. Z. Stanek; B. Scott Gaudi; Brian A. McLeod; Slavko B. Bogdanov; Joel D. Hartman; Ryan C. Hickox; Matthew J. Holman (21 July 2005). "The Hypervelocity Star SDSS J090745.0+024507 is a Short-Period Variable". The Astrophysical Journal. 636 (1): L37. arXiv:astro-ph/0507520. Bibcode:2006ApJ...636L..37F. doi:10.1086/499233. S2CID 14266685. Accessed 18 January 2016.
  4. ^ a b 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, S2CID 14322324
  5. ^ "[BGK2006] HV 1". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 25 June 2020.
  6. ^ Berardelli, Phil (10 February 2005), "In The Stars: Odd Stars, Odder Planets", Space Daily

Further reading[edit]

External links[edit]