Phi2 Cancri

Phi² Cancri is a binary star system in the zodiac constellation of Cancer. Its name is a Bayer designation that is Latinized from φ² Cancri, and abbreviated Phi² Cnc or φ² Cnc. With a combined apparent magnitude of 5.54,^[2] this system is faintly visible to the naked eye under ideal conditions. Parallax measurements give a distance of 345–348 light-years to this system. Both components are separated by 5.126 arcseconds on the sky.^[2] They were identified as a candidate wide binary system in 1988 based on a low angular separation and similar proper motions.^[7]

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

Phi² Cancri

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Cancer
φ2 Cnc A
Right ascension	08h 26m 47.07096s[1]
Declination	+26° 56′ 07.7588″[1]
Apparent magnitude (V)	6.26[2]
φ2 Cnc B
Right ascension	08h 26m 46.83329s[3]
Declination	+26° 56′ 03.6655″[3]
Apparent magnitude (V)	6.31[2]
Characteristics
φ2 Cnc A
Spectral type	A6V[2] or A5IV[4]
φ2 Cnc B
Spectral type	A3V[2] or A2 Vp(4481 wk)[4]
Astrometry
φ2 Cnc A
Proper motion (μ)	RA: −7.487 mas/yr[1] Dec.: +1.202 mas/yr[1]
Parallax (π)	9.4528±0.0351 mas[1]
Distance	345 ± 1 ly (105.8 ± 0.4 pc)
φ2 Cnc B
Proper motion (μ)	RA: −10.112 mas/yr[3] Dec.: +0.110 mas/yr[3]
Parallax (π)	9.3703±0.0306 mas[3]
Distance	348 ± 1 ly (106.7 ± 0.3 pc)
Details
φ2 Cnc A
Mass	2.146±0.041[1] M☉
Radius	3.176±0.067[1] R☉
Luminosity	32.84+0.42 −0.049[1] L☉
Surface gravity (log g)	3.689±0.006[1] cgs
Temperature	7,758+26 −41[1] K
Rotational velocity (v sin i)	149[5] km/s
Age	807±102[1] Myr
φ2 Cnc B
Mass	2.643±0.043[3] M☉
Radius	2.559±0.056[3] R☉
Luminosity	66±1[3] L☉
Surface gravity (log g)	3.896+0.024 −0.027[3] cgs
Temperature	7,595+29 −37[3] K
Rotational velocity (v sin i)	133[5] km/s
Age	309±55[3] Myr
Other designations
φ2 Cnc, 23 Cancri, BD+27°1612, FK5 2633, HIP 41404[6]
φ2 Cnc A: HD 71151, HR 3311, SAO 80188
φ2 Cnc B: HD 71150, HR 3310, SAO 80187
Database references
SIMBAD	φ2 Cnc A
	φ2 Cnc B

φ² Cancri A, of apparent magnitude 6.26, has a spectral type A6V,^[2] making it an A-type main sequence star. A 1995 study found a class of A5IV,^[4] suggesting it is instead an aging subgiant star. It is about 800^[1] million years old and has a high rate of spin, showing a projected rotational velocity of 149 km/s.^[5] This star has 2.1 times the mass of the Sun and 3.18 times the Sun's radius. It is radiating 33 times the luminosity of the Sun from its photosphere at an effective temperature of 7,758 K.^[1]

φ² Cancri B, of apparent magnitude 6.31, is also an A-type main sequence star, of spectral type A3V.^[2] A 1995 study found this to be a chemically peculiar star with a class of A2 Vp(4481 wk).^[4] In addition to displaying evidence of variability, emission lines in the spectrum suggest this is a shell star.^[8] It has 2.6 times the Sun's mass and 2.56 times the radius. The star radiates 66 times the Sun's luminosity at an effective temperature of 7,595 K.^[3] This star is spinning rapidly with a projected rotational velocity of 133 km/s.^[5]