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Proper NameNone
Bayer DesignationNone
Flamsteed Number21 Orionis
HR (BSC)1746
Right Ascension5h 19m 11s
Declination+2° 35' 45"
Distance200 light years
61 parsecs
MagnitudeApparent: +5.34
Absolute: +1.38
Spectral ClassF5II Bright Yellow Bright Giant
Optimum VisibilityDecember / January
NotesShining in the sky at fifth magnitude, 21 Orionis lies northwestward of Orion's Belt. This is a star belonging to the bright giant category, and is more than twenty times as luminous as the Sun. It has approximately twice the Sun's mass and twice its diameter.

The relatively bright star seen here to the east and south of 21 Orionis is seventh-magnitude HD 34745. An F-type star like 21 Orionis itself, HD 34745 is in the foreground of this image, considerably closer to the Solar System but also some ten times less luminous than 21 Orionis, and so it appears fainter as seen from Earth. Imagery provided by Aladin sky atlas


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