Psi Boötis

Psi Boötis is a single,^[10] orange-hued star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from ψ Boötis, and abbreviated Psi Boo or ψ Boo. This is a dim star that is visible to the naked eye with an apparent visual magnitude of +4.55.^[2] Based upon an annual parallax shift of 12.6 mas as seen from the Earth, it is located about 259 light-years (79 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 traversing the sky with a net proper motion of 0.176 arc seconds per year,^[11] and has a radial velocity toward the Sun of −25.72 km/s.^[5]

Psi Boötis

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Boötes
Right ascension	15h 04m 26.743s[1]
Declination	+26° 56′ 51.53″[1]
Apparent magnitude (V)	+4.55[2]
Characteristics
Evolutionary stage	red clump[3]
Spectral type	K2 III[4]
U−B color index	+1.34[2]
B−V color index	+1.23[2]
Astrometry
Radial velocity (Rv)	−25.72±0.18[5] km/s
Proper motion (μ)	RA: −174.718 mas/yr[1] Dec.: −5.036 mas/yr[1]
Parallax (π)	12.6144±0.0896 mas[1]
Distance	259 ± 2 ly (79.3 ± 0.6 pc)
Absolute magnitude (MV)	+0.16[6]
Details
Mass	1.38[7] M☉
Radius	20[5] R☉
Luminosity	135[7] L☉
Surface gravity (log g)	2.2[5] cgs
Temperature	4,302±22[7] K
Metallicity [Fe/H]	−0.35[5] dex
Rotational velocity (v sin i)	3.5[5] km/s
Age	4.16[7] Gyr
Other designations
Aulad al Nathlat[8], ψ Boo, 43 Boötis, BD+27°2447, FK5 557, GC 20285, HD 133582, HIP 73745, HR 5616, SAO 83645[9]
Database references
SIMBAD	data

This star has a stellar classification of K2 III,^[4] matching an evolved K-type giant star. It belongs to the so-called red clump,^[3] indicating that it is generating energy through helium fusion at its core. This star is about four^[7] billion years old and is spinning with a projected rotational velocity of 3.5 km/s.^[5] It has an estimated 1.38^[7] times the mass of the Sun and has expanded to 20^[5] times the Sun's radius. Psi Boötis radiating 135^[7] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,302 K.^[7]

Name

This star, according to Assemani, with another in the right arm that may have been ε Boo (Izar), constituted the Arabs' Al Aulād al Nadhlāt, which he rendered filii altercationis (sons of contention); but the original signifies "the Low, or Mean, Little Ones".^[12]

Al Aulād al Nadhlāt or Aulad al Nathlat was the title of this star in the catalogue of stars in Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars.^[8]