FU Orionis

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FU Orionis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Orion
Right ascension 05h 45m 22.362s[1]
Declination +09° 04′ 12.31″[1]
Apparent magnitude (V) 8.94[1]
Spectral type G3Iav[1]
B−V color index 1.41[1]
Variable type FU Ori[2]
Other designations
FU Ori, BD+09 5427.[1]
Database references

FU Orionis is a variable star in the constellation of Orion, that in 1937 rose in apparent visual magnitude from 16.5 to 9.6, and has since been around magnitude 9.[3][4] For a long time it was considered unique, but in 1970 a similar star, V1057 Cygni, was discovered, and a number of additional examples have been discovered since then. These stars constitute the FU Orionis class of variable stars, GCVS type FU, often nicknamed FUors. These stars are pre–main sequence stars which display an extreme change in magnitude and spectral type.


  1. ^ a b c d e f V* FU Ori -- Variable Star of FU Ori type, database entry, SIMBAD. Accessed on line December 8, 2008.
  2. ^ FU Ori, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line December 8, 2008.
  3. ^ AAVSO: FU Orionis
  4. ^ SIMBAD: V* FU Ori

External links[edit]