Pi2 Ursae Minoris
Pi2 Ursae Minoris (π2 UMi) is a binary star system in the northern circumpolar constellation of Ursa Minor. The pair have apparent magnitudes of 7.32 and 8.15,[9] placing them below the brightness limit of stars that can be readily viewed with the naked eye. They are located about 390 light-years (120 parsecs) away from the Sun. The two have an angular separation of 0.464″ on average, and they orbit each other with a period of about 170 years.[4] The primary star is a F-type dwarf star, and the secondary is G-type.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 15h 39m 38.60827s[1] |
| Declination | +79° 58′ 59.5799″[1] |
| Apparent magnitude (V) | 6.95[2] |
| Characteristics | |
| Spectral type | F1V[3] + G0[4] |
| Astrometry | |
| Radial velocity (Rv) | −32.10 ± 1.8[5] km/s |
| Proper motion (μ) | RA: -32.92[1] mas/yr Dec.: 40.28[1] mas/yr |
| Parallax (π) | 8.33 ± 0.61[1] mas |
| Distance | 390 ± 30 ly (120 ± 9 pc) |
| Absolute magnitude (MV) | +1.51[6] |
| Orbit[4] | |
| Period (P) | 171.62 ± 8.68 yr |
| Semi-major axis (a) | 0.464 ± 0.083″ |
| Eccentricity (e) | 0.961 ± 0.014 |
| Inclination (i) | 135.2 ± 10.5° |
| Longitude of the node (Ω) | 123.4 ± 32.6° |
| Periastron epoch (T) | 1904.15 ± 2.89 |
| Argument of periastron (ω) (secondary) | 274.0 ± 22.4° |
| Details | |
| Temperature | 6.858[7] K |
| Metallicity [Fe/H] | +0.09[8] dex |
| Age | 1.20[8] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
References
- van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
- Ginestet, N; Carquillat, J. M; Jaschek, C (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.
- Hartkopf, William I.; Mason, Brian D.; Rafferty, Theodore J. (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.
- "* pi.02 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 31 July 2017.
- 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.
- Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy and Astrophysics. 591: A118. arXiv:1605.07384. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497.
- Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (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.
- "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 31 July 2017.
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