Astronomy:Pi2 Ursae Minoris
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 15h 39m 38.61131s[1] |
| Declination | +79° 58′ 59.5495″[1] |
| Apparent magnitude (V) | 6.89[2] (7.32 + 8.15)[3] |
| Characteristics | |
| Spectral type | F1V[4] + G0[5] |
| B−V color index | 0.392±0.015[2] |
| Astrometry | |
| Radial velocity (Rv) | −32.10±1.8[6] km/s |
| Proper motion (μ) | RA: −32.643[1] mas/yr Dec.: 41.425[1] mas/yr |
| Parallax (π) | 8.1090 ± 0.2844[1] mas |
| Distance | 400 ± 10 ly (123 ± 4 pc) |
| Absolute magnitude (MV) | 1.69±0.08[6] |
| Orbit[5] | |
| 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 | |
| Mass | 1.87[7] M☉ |
| Radius | 3.82+0.59 −1.27[1] R☉ |
| Luminosity | 16.5±0.7[1] L☉ |
| Temperature | 6,858±80[7] K |
| Metallicity [Fe/H] | +0.09[7] dex |
| Age | 1.20[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Pi2 Ursae Minoris, which is Latinized from π2 UMi / π2 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,[2] which can be viewed with a pair of binoculars.[9] 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.[6]
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,[5] so the grade of the orbital elements is rated as poor.[3] The system has a high eccentricity of 0.96 and they orbit each other with a period of roughly 172 years.[5] The magnitude 7.32 primary is an F-type main-sequence star with a stellar classification of F1V.[4] The fainter secondary has a magnitude of 8.15[3] and is G-type star.[5] At present the angular separation between both stars is 0.67 arcseconds [1].
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 3.2 Malkov, O. Yu. et al. (2012). "Dynamical Masses of a Selected Sample of Orbital Binaries". Astronomy & Astrophysics 546: 5. doi:10.1051/0004-6361/201219774. A69. Bibcode: 2012A&A...546A..69M.
- ↑ 4.0 4.1 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. doi:10.1051/aas:1999444. Bibcode: 1999A&AS..134..473G.
- ↑ 5.0 5.1 5.2 5.3 5.4 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. doi:10.1088/0004-6256/135/4/1334. Bibcode: 2008AJ....135.1334H.
- ↑ 6.0 6.1 6.2 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. doi:10.1051/0004-6361:20077221. Bibcode: 2007A&A...475..519H.
- ↑ 7.0 7.1 7.2 7.3 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, doi:10.1051/0004-6361/201016276, Bibcode: 2011A&A...530A.138C
- ↑ "pi.02 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=pi.02+UMi.
- ↑ "The astronomical magnitude scale". http://www.icq.eps.harvard.edu/MagScale.html.
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