Alpha Caeli

α Caeli

250px Alpha Caeli is at lower center.
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Caelum
A
Right ascension	04h 40m 33.7125s
Declination	−41° 51′ 49.509″
Apparent magnitude (V)	4.456
B
Right ascension	04h 40m 34.0s
Declination	−41° 51′ 51″
Apparent magnitude (V)	12.5
Characteristics
A
Spectral type	F2V
U−B color index	+0.01
B−V color index	+0.34
B
Spectral type	M0.5
Astrometry
A
Radial velocity (Rv)	–0.6 ± 0.9 km/s
Proper motion (μ)	RA: –141.18 mas/yr Dec.: –74.95 mas/yr
Parallax (π)	49.67 ± 0.53 mas
Distance	65.7 ± 0.7 ly (20.1 ± 0.2 pc)
Absolute magnitude (MV)	3.39
B
Radial velocity (Rv)	−0.6 ± 0.9 km/s
Proper motion (μ)	RA: −147 mas/yr Dec.: −78 mas/yr
Details
A
Mass	1.48 M☉
Radius	1.3 R☉
Surface gravity (log g)	4.01 cgs
Temperature	6,991 K
Metallicity	$\begin{smallmatrix}\left[\frac{M}{H}\right]\ =\ -0.10\end{smallmatrix}$
Rotational velocity (v sin i)	47.8 ± 2.4 km/s
Age	0.9 (0.7–1.3) × 109 years
B
Mass	0.3 M☉
Temperature	3800 K
Other designations
A: CCDM J04406-4152A, CD−42°1587, CPD−42°513, FK5 1129, GC 5708, Gl 174.1 A, GJ 9164 A, HD 29875, HIP 21770, HR 1502, IDS 04373-4203 A, SAO 216926. B: CCDM J04406-4152B, CD−42°1587B, CPD−42°513B, Gl 174.1 B, GJ 9164 B, IDS 04373-4203 B.
Database references
A
SIMBAD	data
B
SIMBAD	data

Alpha Caeli (α Cae, α Caeli) is a double star system in the constellation Caelum.

Alpha Caeli A is an F-type main sequence star with a stellar classification of F2V and an apparent magnitude of +4.44. It has 1.48 times the mass of the Sun and 1.3 times the solar radius. The projected rotational velocity at the stellar equator is 47.8 km/s. It is suspected of being a Delta Scuti variable star.

The companion is a spectral class M0.5V red dwarf star with absolute magnitude 9.80. It is a UV Ceti variable star that undergoes random increases in luminosity. This star is currently separated from the primary by an angle of 6.6 arcseconds, which indicates an orbit with a semimajor axis whose expected value is 206 AU.

Alpha Caeli is approximately 65.7 light years from Earth and is an estimated 900 million years old. The space velocity components of this system are U = 10, V = 6 and W = -10 km/s. It is orbiting the Milky Way galaxy at an average distance of 8.006 kpc from the core and with an orbital eccentricity of 0.07. This orbit lies close to the galactic plane, and the system travels no more than 0.05 kpc above or below this plane. Alpha Caeli is probably a member of the Ursa Major moving group of stars that have similar kinematic properties and probably originated from the same star cluster.