4 Eridani (HIP 13782)

4 Eridani is a white subgiant star in the constellation Eridanus. At 159 light years away, it shines at an apparent visual magnitude of 5.45. It is moving through the Galaxy at a speed of 38.1 km/s relative to the Sun.

Sky position: RA 2h 57.4m, Dec -23° 51.7'

Common designations: 4 Eridani, HR 883, HD 18454, HIP 13782, Gaia DR3 5078091055566935296

4 Eridani has the spectral type A5IV/V. A-type stars are white stars with surface temperatures of roughly 7,500 to 10,000 K. Their spectra are dominated by strong hydrogen lines, and many of them rotate rapidly. 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 4 Eridani in the sky

4 Eridani lies in Eridanus. With a declination of -23° 51.7', it is visible from the entire Southern Hemisphere and from the Northern Hemisphere up to about latitude 66° N. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around November, which makes the weeks around that month the best time to observe it.

Tabulated data for 4 Eridani

Astrometry and spectroscopy

Right Ascension (J2000)	44.34902728° (2h 57.4m)
Declination (J2000)	-23.86216557° (-23° 51.7')
Galactic Longitude	213.46412238°
Galactic Latitude	-61.46376587°
Proper motion RA	101.71 mas/yr
Proper motion Dec	-36.60 mas/yr
Parallax	20.54 ± 0.06 mas
Spectral Type	A5IV/V
Radial Velocity	28.80 km/s

Photometry

Band	Magnitude	Abs. Mag.
B	5.68	2.24
V	5.45	2.01
J	5.06	1.63
H	5.01	1.58
K	4.92	1.48

Colour index B-V: +0.23

Derivations

Heliocentric distance: 48.68 pc (159 light years) (0.3% margin of error)
Absolute visual magnitude: 2.01
Transverse velocity: 24.9 km/s
Space velocity relative to the Sun: 38.1 km/s
Galactic position (X, Y, Z): -19.4 pc, -12.8 pc, -42.8 pc
Galactic velocity (U, V, W): -19.3 km/s, -29.1 km/s, -15.3 km/s

Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.