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Pi Ursae Minoris, which is Latinized from π UMi / π Ursae Minoris, is a binary star system in the northern circumpolar constellation of Ursa Minor. The pair have a combined apparent visual magnitude of 6.89, which can be viewed with a pair of binoculars. They are located at a distance of approximately 400 light years from the Sun based on parallax, but are drifting closer with a radial velocity of −32 km/s.

This star was found to be a double system by O. Struve in 1832, and the pair have now completed a full orbit. There is a lot of scatter in the data though, so the grade of the orbital elements is rated as poor. The system has a high eccentricity of 0.96 and they orbit each other with a period of roughly 172 years. The magnitude 7.32 primary is an F-type main-sequence star with a stellar classification of F1V. The fainter secondary has a magnitude of 8.15 and is G-type star. At present the angular separation between both stars is 0.67 arcseconds .

References

1. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
2. ^ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
3. ^ Malkov, O. Yu.; et al. (2012). "Dynamical Masses of a Selected Sample of Orbital Binaries". Astronomy & Astrophysics. 546: 5. Bibcode:2012A&A...546A..69M. doi:10.1051/0004-6361/201219774. A69.
4. ^ Ginestet, N.; et al. (1999). "Spectral classifications in the near infrared of stars with composite spectra. III. Study of a sample of 137 objects with the Aurelie spectrograph". Astronomy and Astrophysics Supplement. 134 (3): 473. Bibcode:1999A&AS..134..473G. doi:10.1051/aas:1999444.
5. ^ Hartkopf, William I.; et al. (2008). "Speckle Interferometry at the Usno Flagstaff Station: Observations Obtained in 2003-2004 and 17 New Orbits". The Astronomical Journal. 135 (4): 1334. Bibcode:2008AJ....135.1334H. doi:10.1088/0004-6256/135/4/1334.
6. ^ Holmberg, J.; et al. (2007). "The Geneva-Copenhagen survey of the Solar neighbourhood. II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk". Astronomy & Astrophysics. 475 (2): 519–537. arXiv:0707.1891. Bibcode:2007A&A...475..519H. doi:10.1051/0004-6361:20077221. S2CID 119054949.
7. ^ Casagrande, L.; et al. (June 2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy and Astrophysics, 530: A138, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276, S2CID 56118016
8. "pi.02 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-08.
9. "The astronomical magnitude scale". International Comet Quarterly. Retrieved 2020-12-17.

v t e Constellation of Ursa Minor
List of stars in Ursa Minor Ursa Minor in Chinese astronomy
Stars	Bayer α (Polaris) β (Kochab) γ (Pherkad) δ (Yildun) ε ζ η θ λ π π Flamsteed 3 4 5 6 8 (Baekdu) 9 10 11 (γ) 12 14 17 19 20 24 Variable R S T U V W Z RR RU RW SS UY VX HR 5184 5596 HD 150706 Other Calvera H1504+65 LP 40-365 WD 1337+705 WISE 1506+7027
Exoplanets β Ursae Minoris b 8 Ursae Minoris b (Halla) 11 Ursae Minoris b TOI-4138 b
Galaxies	NGC 5034 5144 5939 6217 6251 6331 Other 3C 309.1
Galaxy clusters Abell 2256
Category

• F-type main-sequence stars
• G-type main-sequence stars
• Binary stars
• Ursa Minor
• Bayer objects
• Durchmusterung objects
• Flamsteed objects
• Henry Draper Catalogue objects
• Hipparcos objects