Sigma1 Cancri

Sigma¹ Cancri is a binary star system^[9] in the zodiac constellation of Cancer. Its name is a Bayer designation that is Latinized from σ¹ Cancri, and abbreviated Sigma¹ Cnc or σ¹ Cnc. The primary component is faintly visible to the naked eye, with an apparent visual magnitude of +5.68.^[3] Based upon an annual parallax shift of 15.51 mas as seen from Earth,^[2] this star is located around 221 light-years (68 pc) from the Sun. It is moving further away with a line of sight velocity of −11 km/s.^[6]

For other stars with this Bayer designation, see σ Cancri.

Sigma¹ Cancri

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Cancer[1]
Right ascension	08h 52m 34.622s[2]
Declination	+32° 28′ 26.97″[2]
Apparent magnitude (V)	5.68[3] + 13.3[4]
Characteristics
Spectral type	A8 Vas[5]
U−B color index	+0.08[3]
B−V color index	+0.20[3]
Variable type	Constant[1]
Astrometry
Radial velocity (Rv)	−11.26±0.25[6] km/s
Proper motion (μ)	RA: −5.598 mas/yr[2] Dec.: +15.832 mas/yr[2]
Parallax (π)	14.7289±0.0959 mas[2]
Distance	221 ± 1 ly (67.9 ± 0.4 pc)
Absolute magnitude (MV)	+1.62[1]
Details
σ1 Cnc A
Mass	1.70[7] M☉
Luminosity	18[8] L☉
Surface gravity (log g)	4.44[7] cgs
Temperature	8,116±276[7] K
Rotational velocity (v sin i)	84[8] km/s
Age	301[7] Myr
σ1 Cnc B
Mass	0.62[9] M☉
Other designations
σ1 Cnc, 51 Cancri, BD+33°1770, HD 75698, HIP 43584, HR 3519, SAO 61102, WDS J08526+3228A[10]
Database references
SIMBAD	data

This is a chemically peculiar^[8] A-type main sequence star with a stellar classification of A8 Vas.^[5] At an age of about 301^[7] million years, Sigma¹ Cancri is around 67% of the way through its main sequence lifespan.^[8] The star has 1.7^[7] times the mass of the Sun and is radiating 18^[8] times the Sun's luminosity from its photosphere at an effective temperature of 8,116 K.^[7]

There is a magnitude 13.3 companion at an angular separation of 5.2 arc seconds along a position angle of 276°, as of 2011.^[4] At that distance, the pair have a projected separation of 333.2 AU (0.005269 ly). This star, designated Sigma¹ Cancri B, has an estimated 62% of the mass of the Sun.^[9]