Alkes (HIP 53740)

Alkes is an orange giant star in the constellation Crater. At 160 light years away, it shines at an apparent visual magnitude of 4.07. It is moving through the Galaxy at a speed of 121.4 km/s relative to the Sun.

Sky position: RA 10h 59.8m, Dec -18° 17.9'

Common designations: Alkes, Alpha Crateris, 7 Crateris, HR 4287, HD 95272, HIP 53740, Gaia DR3 3553136288324444544

Alkes has the spectral type K0IIIb. K-type stars are orange stars with surface temperatures of about 3,900 to 5,300 K. Their spectra are rich in neutral metal lines and, in the cooler examples, molecular bands. Its luminosity class III marks it as a giant: an evolved star that has left the main sequence and swollen to many times its original size.

How to find Alkes in the sky

Alkes lies in Crater. With a declination of -18° 17.9', it is visible from the entire Southern Hemisphere and from the Northern Hemisphere up to about latitude 72° N. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around March, which makes the weeks around that month the best time to observe it.

Tabulated data for Alkes

Astrometry and spectroscopy

Right Ascension (J2000)	164.94360482° (10h 59.8m)
Declination (J2000)	-18.29878622° (-18° 17.9')
Galactic Longitude	269.05174351°
Galactic Latitude	37.12035462°
Proper motion RA	-462.30 mas/yr
Proper motion Dec	128.61 mas/yr
Parallax	20.37 ± 0.17 mas
Spectral Type	K0IIIb
Radial Velocity	47.54 km/s

Photometry

Band	Magnitude	Abs. Mag.
U	6.14	2.68
B	5.16	1.70
V	4.07	0.61
R	3.27	-0.19
I	2.72	-0.74
J	2.29	-1.17
H	1.76	-1.70
K	1.62	-1.84

Colour index B-V: +1.09

Derivations

Heliocentric distance: 49.09 pc (160 light years) (0.8% margin of error)
Absolute visual magnitude: 0.61
Transverse velocity: 111.7 km/s
Space velocity relative to the Sun: 121.4 km/s
Galactic position (X, Y, Z): -0.6 pc, -39.1 pc, 29.6 pc
Galactic velocity (U, V, W): -108.3 km/s, -54.7 km/s, 4.2 km/s

Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.