66 Eridani (HIP 23794)

66 Eridani is a blue-white main-sequence star in the constellation Eridanus. At 304 light years away, it shines at an apparent visual magnitude of 5.12. It is moving through the Galaxy at a speed of 31.2 km/s relative to the Sun.

Sky position: RA 5h 6.8m, Dec -4° 39.3'

Common designations: 66 Eridani, EN Eridani, HR 1657, HD 32964, HIP 23794, Gaia DR3 3212019815193261568

66 Eridani has the spectral type B9V. B-type stars are hot (about 10,000 to 30,000 K), luminous and blue-white. They are massive, short-lived stars, typically only tens of millions of years old, and are common in young clusters and OB associations. Its luminosity class V means it is a main-sequence (dwarf) star, still fusing hydrogen into helium in its core like the Sun.

How to find 66 Eridani in the sky

66 Eridani lies in Eridanus. With a declination of -4° 39.3', it is visible from the entire Southern Hemisphere and from the Northern Hemisphere up to about latitude 85° N. 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 66 Eridani

Astrometry and spectroscopy

Right Ascension (J2000)	76.69021995° (5h 6.8m)
Declination (J2000)	-4.65516695° (-4° 39.3')
Galactic Longitude	204.77572918°
Galactic Latitude	-25.35456380°
Proper motion RA	9.31 mas/yr
Proper motion Dec	-0.52 mas/yr
Parallax	10.73 ± 0.11 mas
Spectral Type	B9V
Radial Velocity	30.90 km/s

Photometry

Band	Magnitude	Abs. Mag.
U	4.89	0.04
B	5.06	0.21
V	5.12	0.27
J	5.23	0.38
H	5.22	0.37
K	5.20	0.36

Colour index B-V: -0.06

Derivations

Heliocentric distance: 93.22 pc (304 light years) (1.0% margin of error)
Absolute visual magnitude: 0.27
Transverse velocity: 4.1 km/s
Space velocity relative to the Sun: 31.2 km/s
Galactic position (X, Y, Z): -76.5 pc, -35.3 pc, -39.9 pc
Galactic velocity (U, V, W): -25.8 km/s, -14.3 km/s, -10.0 km/s

Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.