Kappa Cassiopeiae

κ Cassiopeiae

Template:Location mark Location of κ Cassiopeiae (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cassiopeia
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	4.12 - 4.21
Characteristics
Spectral type	BC0.7 Ia
Apparent magnitude (U)	3.50
Apparent magnitude (B)	4.276
Apparent magnitude (J)	4.141
Apparent magnitude (H)	4.148
Apparent magnitude (K)	4.013
U−B Template:Engvar	−0.776
B−V Template:Engvar	+0.0869
J−H Template:Engvar	−0.0069
J−K Template:Engvar	+0.128
Variable type	α Cyg
Astrometry
Radial velocity (Rv)	0.30 km/s
Proper motion (μ)	RA: +3.65 mas/yr Dec.: −2.07 mas/yr
Parallax (π)	0.73±0.17 mas
Distance	approx. Template:Rnd ly (approx. Template:Rnd pc)
Absolute magnitude (MV)	−7.1
Details
Mass	33 Template:Solar mass
Radius	39 Template:Solar radius
Luminosity	490,000 Template:Solar luminosity
Surface gravity (log g)	2.79 cgs
Temperature	24,600 K
Rotational velocity (v sin i)	58 km/s
Age	4.5 Myr
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
15 Cassiopeiae, HR 130, HD 2905, BD+62°102, FK5 16, HIP 2599, SAO 11256, GC 645, MWC 7
Database references
SIMBAD	data

File:Kappa Cassiopeiae.jpg

Kappa Cassiopeiae and its bow shock. Spitzer infrared image (NASA/JPL-Caltech)

Kappa Cassiopeiae (κ Cas, κ Cassiopeiae) is a star in the constellation Cassiopeia.

κ Cassiopeiae has an unusual spectrum that has anomalously weak nitrogen lines, taken as an actual nitrogen deficiency in the atmosphere. This is indicated by the modified letter C on the assumption that it is also carbon-rich, although this might not actually be the case. It is also interpolated to BC0.7, being slightly hotter than a standard B1 star.

κ Cassiopeiae is assumed to be a member of the Cassiopeia OB14 stellar association (Cas OB14) and treated as being at a distance of about , while its distance found from the Hipparcos parallax is about 1,400 parsecs. Its Gaia parallaxes are somewhat uncertain due to the brightness of the star, but a modern determination of the distance to Cas OB14 is .

File:KappaCasLightCurve.png

A light curve for Kappa Cassiopeiae, plotted from Hipparcos data

It is classified as an Alpha Cygni type variable star and its brightness varies by a few hundredths of a magnitude. Periods of two hours, 2.65 days, and nine days have been reported from observations at different times.

It is a runaway star. Its magnetic field and wind of particles creates a visible bow shock 4 light-years ahead of it, colliding with the diffuse, and usually invisible, interstellar gas and dust. This is about the same distance that Earth is from Proxima Centauri, the nearest star to the Sun. The dimensions of the bow shock are vast: around 12 light-years long and 1.8 light-years wide.