Upsilon1 Cassiopeiae

υ¹ Cassiopeiae

Template:Location mark Location of υ1 Cassiopeiae (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Cassiopeia
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	4.82
Characteristics
Evolutionary stage	red clump
Spectral type	K2 III
U−B Template:Engvar	+1.25
B−V Template:Engvar	+1.21
Astrometry
Radial velocity (Rv)	−23.57 km/s
Proper motion (μ)	RA: Template:Val mas/yr Dec.: Template:Val mas/yr
Parallax (π)	9.93±0.49 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−0.644
Details
Mass	1.39 Template:Solar mass
Radius	21 Template:Solar radius
Luminosity	174 Template:Solar luminosity
Surface gravity (log g)	1.76 cgs
Temperature	Template:Val K
Metallicity [Fe/H]	−0.25 dex
Rotational velocity (v sin i)	1.1 km/s
Age	4.75 Gyr
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBAD	data

File:Upsilon Cassiopeiae.jpg

υ¹ Cassiopeiae is the bright star in the lower right. The bright star in the upper left is υ² Cassiopeiae.

Upsilon¹ Cassiopeiae (υ¹ Cassiopeiae) is an astrometric binary star system in the northern constellation of Cassiopeia. It is visible to the naked eye with an apparent visual magnitude of 4.82. Based upon an annual parallax shift of 9.93 mas as seen from Earth, this system is located about 330 light years from the Sun.

The visible component is an evolved K-type giant star with a stellar classification of K2 III. With an estimated age of 4.75 billion years, it is a red clump star that is generating energy through the fusion of helium at its core. The measured angular diameter, after correction for limb darkening, is Template:Val. At the estimated distance of the star, this yields a physical size of about 21 times the radius of the Sun. It has 1.39 times the mass of the Sun and is radiating 174 times the Sun's luminosity from its expanded photosphere at an effective temperature of 4,422 K.

There is a magnitude 12.50 visual companion at an angular separation of 17.80 arc seconds along a position angle of 61°, as of 2003. A more distant magnitude 12.89 companion lies at a separation of 93.30 arc seconds along a position angle of 125°, as measured in 2003. Neither star appears to be physically associated with υ¹ Cas.