Pi2 Ursae Minoris

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Pi2 Ursae Minoris
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
Distance390 ± 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°
Other designations
18 UMi, BD+80° 487, HD 141652, HIP 76695, SAO 2588
Database references
SIMBADdata

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,[7] 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]

References[edit]

  1. ^ a b c d e 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.
  2. ^ 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.
  3. ^ 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.
  4. ^ a b c d 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.
  5. ^ "* pi.02 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 31 July 2017.
  6. ^ 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.
  7. ^ "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 31 July 2017.