15 Orionis (HIP 24010)

15 Orionis is a yellow-white subgiant star in the constellation Orion. At 331 light years away, it shines at an apparent visual magnitude of 4.82. It is moving through the Galaxy at a speed of 29.1 km/s relative to the Sun.

Sky position: RA 5h 9.7m, Dec +15° 35.8'

Common designations: 15 Orionis, HR 1676, HD 33276, HIP 24010, Gaia DR3 3392331785048050176

15 Orionis has the spectral type F2IV. F-type stars are yellow-white stars of about 6,000 to 7,500 K, slightly hotter and more massive than the Sun. Their hydrogen lines are weaker than in A stars and metal lines become prominent. Its luminosity class IV marks it as a subgiant: it has exhausted hydrogen in its core and is beginning to expand toward the giant phase.

How to find 15 Orionis in the sky

15 Orionis lies in Orion. With a declination of +15° 35.8', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 74° S. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around January, which makes the weeks around that month the best time to observe it.

Tabulated data for 15 Orionis

Astrometry and spectroscopy

Right Ascension (J2000)	77.42482144° (5h 9.7m)
Declination (J2000)	15.59721305° (+15° 35.8')
Galactic Longitude	186.73648479°
Galactic Latitude	-14.21470288°
Proper motion RA	4.18 mas/yr
Proper motion Dec	-7.26 mas/yr
Parallax	9.84 ± 0.55 mas
Spectral Type	F2IV
Radial Velocity	28.79 km/s

Photometry

Band	Magnitude	Abs. Mag.
U	5.33	0.30
B	5.14	0.11
V	4.82	-0.21
R	4.50	-0.53
I	4.31	-0.72
J	4.13	-0.90
H	4.22	-0.82
K	3.96	-1.08

Colour index B-V: +0.32

Derivations

Heliocentric distance: 101.59 pc (331 light years) (5.6% margin of error)
Absolute visual magnitude: -0.21
Transverse velocity: 4.0 km/s
Space velocity relative to the Sun: 29.1 km/s
Galactic position (X, Y, Z): -97.8 pc, -11.6 pc, -24.9 pc
Galactic velocity (U, V, W): -27.2 km/s, -7.3 km/s, -7.3 km/s

Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.