Magnitude 4.873 Apparent magnitude (V) 4.873 | ||
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Similar Omega Orionis, Eta Orionis, Pi3 Orionis | ||
25 Orionis, less commonly known by its Bayer designation Psi1 Orionis (ψ1 Orionis, ψ1 Ori) is a fifth-magnitude star in the constellation Orion. Its kinematics place it among a dense cluster of almost 200 low-mass pre-main-sequence stars in the Orion OB1a subassociation known as the 25 Orionis group.
Properties
Like the star Pleione in the Pleiades open cluster, 25 Ori is a Be star with a gaseous circumstellar disk. The SIMBAD astronomical database lists its spectral class as B1Vpe. The suffix "pe" refers to "Emission lines with peculiarity", a classification typical of many Be stars whose peculiar emissions come from the gaseous equatorial disks formed of material ejected from the star.
25 Orionis is a fast rotator, clocking a rotational velocity of 316 km/s, significantly faster than Achernar's speed of 251 km/s in the constellation Eridanus. Having a radius of 6 R☉, the star rotates on its axis roughly once every 23 hours. With a mass in excess of 10 M☉, the star is expected to explode as a supernova.