Psi Boötis
Star in the constellation of Bootes
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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]
 | |
| 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]