Phi Boötis

Phi Boötis is a single,^[9] yellow-hued star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from φ Boötis, and abbreviated Phi Boo or φ Boo. This star is dimly visible to the naked eye with an apparent visual magnitude of +5.24.^[2] Based upon an annual parallax shift of 18.58 mas as seen from the Earth,^[1] it is located 176 light-years (54 pc) from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.09 due to interstellar dust.^[6] It is moving closer to the Sun with a radial velocity of −10.6 km/s.^[5]

Phi Boötis

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Boötes
Right ascension	15h 37m 49.598s[1]
Declination	+40° 21′ 12.36″[1]
Apparent magnitude (V)	+5.24[2]
Characteristics
Evolutionary stage	red clump[3]
Spectral type	G7 III-IV Fe-2[4]
U−B color index	+0.53[2]
B−V color index	+0.88[2]
Astrometry
Radial velocity (Rv)	−10.62±0.30[5] km/s
Proper motion (μ)	RA: +61.380 mas/yr[1] Dec.: +59.791 mas/yr[1]
Parallax (π)	18.5752±0.0555 mas[1]
Distance	175.6 ± 0.5 ly (53.8 ± 0.2 pc)
Absolute magnitude (MV)	+1.67[6]
Details
Mass	1.43[6] M☉
Radius	5[5] R☉
Luminosity	17[5] L☉
Surface gravity (log g)	2.82±0.14[7] cgs
Temperature	4,945±57[7] K
Metallicity [Fe/H]	−0.51±0.06[7] dex
Rotational velocity (v sin i)	0.0[5] km/s
Age	3.16[6] Gyr
Other designations
φ Boo, 54 Boötis, BD+40°2907, FK5 580, GC 21032, HD 139641, HIP 76534, HR 5823, SAO 45643[8]
Database references
SIMBAD	data

The stellar classification of Phi Boötis is G7 III-IV Fe-2,^[4] which would suggest it is an evolving G-type star that shows spectral traits of both a subgiant and a giant star. However, Alves (2000) has it listed as a member of the so-called "red clump", indicating that it is an aging giant star that is generating energy through helium fusion at its core.^[3] The 'Fe-2' suffix notation in its class means that it displays a significant underabundance of iron in its spectrum. Around three billion years old,^[6] Phi Boötis has an estimated 1.43^[6] times the mass of the Sun and 5^[5] times the Sun's radius. It is radiating 17^[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of about 4,945 K.^[7]