40 Boötis

40 Boötis is a single^[8] star located 166.5 light years away from the Sun in the northern constellation of Boötes. It is visible to the naked eye as a dim, yellow-white hued star with an apparent visual magnitude of 5.64.^[2] The star is moving away from the Earth with a heliocentric radial velocity of +12 km/s.^[5]

40 Boötis

Observation data Epoch J2000      Equinox J2000
Constellation	Boötes
Right ascension	14h 59m 36.94745s[1]
Declination	+39° 15′ 55.1994″[1]
Apparent magnitude (V)	5.64[2]
Characteristics
Evolutionary stage	giant[3]
Spectral type	F1 III–IV[4]
B−V color index	0.336±0.004[2]
Astrometry
Radial velocity (Rv)	+12.3±0.7[5] km/s
Proper motion (μ)	RA: −32.109[1] mas/yr Dec.: 41.246[1] mas/yr
Parallax (π)	19.5911±0.0702 mas[1]
Distance	166.5 ± 0.6 ly (51.0 ± 0.2 pc)
Absolute magnitude (MV)	2.08[2]
Details
Mass	1.47[6] M☉
Radius	2.35+0.34 −0.13[1] R☉
Luminosity	11.585±0.054[1] L☉
Surface gravity (log g)	3.88[6] cgs
Temperature	7,070±240[6] K
Metallicity [Fe/H]	−0.29[5] dex
Rotational velocity (v sin i)	72.5[3] km/s
Age	1.166[6] Gyr
Other designations
40 Boo, BD+39°2820, FK5 3182, HD 132772, HIP 73369, HR 5588, SAO 64449[7]
Database references
SIMBAD	data

The Hipparcos catalogue (1997) lists a stellar classification of F1 III–IV,^[9] matching the luminosity class of an aging star that is evolving into a giant.^[3] Earlier, Cowley and Bidelman (1979) listed a class of F2 III,^[10] while Sato and Kuji (1990) found a main sequence class of F0V.^[11] It is around 1.2^[6] billion years old with a relatively high rotation rate, showing a projected rotational velocity of 72.5 km/s.^[3] The star has 1.5^[6] times the mass of the Sun and 2.4^[1] times the Sun's radius. It is radiating 11.6^[1] times the luminosity of the Sun from its photosphere at an effective temperature of 7,070 K.^[6]