Psi Ursae Majoris

Psi Ursae Majoris
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings

Location of ψ Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ursa Major
Right ascension 11h 09m 39.8083s[1]
Declination +44° 29′ 54.5559″[1]
Apparent magnitude (V) +3.01[2]
Characteristics
Evolutionary stage Giant star
Spectral type K1 III[3]
U−B color index +1.12[2]
B−V color index +1.14[2]
Astrometry
Radial velocity (Rv)–3.39[4] km/s
Proper motion (μ) RA: –62.02 mas/yr[1]
Dec.: –27.78 mas/yr[1]
Parallax (π)23.2272 ± 0.2513 mas[1]
Distance140 ± 2 ly
(43.1 ± 0.5 pc)[1]
Absolute magnitude (MV)−0.27[5]
Details[6]
Mass2.31±0.13 M☉
Radius19.12[6]–20.79[7] R☉
Luminosity140±3 L☉
Surface gravity (log g)2.12±0.05 cgs
Temperature4,543±6 K
Metallicity [Fe/H]−0.11±0.03 dex
Rotational velocity (v sin i)5.5[8] km/s
Other designations
ψ Ursae Majoris, ψ UMa, Psi UMa, 52 Ursae Majoris, BD+45 1897, FK5 420, GC 15340, HD 96833, HIP 54539, HR 4335, PPM 52277, SAO 43629.[9]
Database references
SIMBADdata

Psi Ursae Majoris (Psi UMa, ψ Ursae Majoris, ψ UMa) is a star in the northern circumpolar constellation of Ursa Major. It has an apparent visual magnitude of +3.01,[2] making it a third magnitude star and one of the brighter members of the constellation. Parallax measurements place it at a distance of 140 light-years (43 parsecs) from Earth.[1] This is sufficiently close that the magnitude of the star is only reduced by 0.05 due to extinction.[4] In Chinese astronomy, Psi Ursae Majoris is called Tien Tsan or Ta Tsun, "Extremely Honorable".[10] The name was possibly derived from the word 太尊, Pinyin: Tàizūn, meaning Royals, because this star stands alone as the only member of the Royals asterism within the Purple Forbidden enclosure (see Chinese constellation).

The spectrum of this star matches a stellar classification of K1 III,[3] with the luminosity class of 'III' indicating this is an evolved giant star that has exhausted the supply of hydrogen at its core. As a consequence, it has expanded to around 20 times the radius of the Sun.[7][6] It is radiating roughly 140 times the luminosity of the Sun from its enlarged outer envelope at an effective temperature of 4,543 K.[6] At this heat, the star glows with the orange hue of a K-type star.[11]

Psi Ursae Majoris is a member of the thin disk population of the Milky Way. It is following an orbit through the galaxy with a low eccentricity of 0.02 that will carry it between 26.5–27.8 kly (8.1–8.5 kpc) from the Galactic Center. The low inclination of its orbit means the star will only stray 130 ly (40 pc) from the galactic plane.[12]

  1. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c d Cite error: The named reference mnras172_667 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference aaa508_3_1313 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference aaa430_165 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Cardini2005 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Soubiran2024 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference gray2019 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference aj135_1_209 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference allen was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference aaa480_1_91 was invoked but never defined (see the help page).