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Pi1 Ursae Minoris 
Summary
Pi1 Ursae Minoris[14] is a common proper motion binary star[15] system in the northern circumpolar constellation of Ursa Minor. The pair have apparent visual magnitudes of +6.58 and +7.31, with a combined magnitude of 6.1.[2] They are located about 71 light years from the Sun. The two have an angular separation of 31.4 arc seconds,[15] which corresponds to a physical separation of about 680 AU,[16] and orbit each other with a period of about 13,100 years.[9]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Ursa Minor |
| π1 UMi A | |
| Right ascension | 15h 29m 11.18599s[1] |
| Declination | +80° 26′ 54.9713″[1] |
| Apparent magnitude (V) | +6.58[2] |
| π1 UMi B | |
| Right ascension | 15h 29m 23.59426s[1] |
| Declination | +80° 27′ 00.9675″[1] |
| Apparent magnitude (V) | +7.31[2] |
| Characteristics | |
| π1 UMi A | |
| Spectral type | G1.5 V(n)[3] |
| U−B color index | +0.13[2] |
| B−V color index | +0.67[2] |
| π1 UMi B | |
| Spectral type | G9 V[4] |
| U−B color index | +0.37[2] |
| B−V color index | +0.79[2] |
| Astrometry | |
| π1 UMi A | |
| Radial velocity (Rv) | −16.27±0.09[5] km/s |
| Proper motion (μ) | RA: −225.109[6] mas/yr Dec.: +107.575[6] mas/yr |
| Parallax (π) | 45.8577 ± 0.0328 mas[6] |
| Distance | 71.12 ± 0.05 ly (21.81 ± 0.02 pc) |
| Absolute magnitude (MV) | 4.94±0.04[7] |
| π1 UMi B | |
| Radial velocity (Rv) | −15.40±0.70[5] km/s |
| Proper motion (μ) | RA: −217.817[8] mas/yr Dec.: +105.947[8] mas/yr |
| Parallax (π) | 45.8038 ± 0.0352 mas[8] |
| Distance | 71.21 ± 0.05 ly (21.83 ± 0.02 pc) |
| Details | |
| π1 UMi A | |
| Mass | 1.02[9] M☉ |
| Radius | 0.98[6] R☉ |
| Luminosity | 0.929[6] L☉ |
| Surface gravity (log g) | 4.40[10] cgs |
| Temperature | 5,771[10] K |
| Metallicity [Fe/H] | −0.22[11] dex |
| Age | 9.22±3.84[12] Gyr |
| π1 UMi B | |
| Mass | 0.92[9] M☉ |
| Radius | 0.84[8] R☉ |
| Luminosity | 0.520[8] L☉ |
| Surface gravity (log g) | 4.50[10] cgs |
| Temperature | 5,408[10] K |
| Metallicity [Fe/H] | −0.18[11] dex |
| Other designations | |
| π1 UMi A: BD+80°480, HD 139777, HIP 75809, HR 5829, SAO 2556 | |
| π1 UMi B: BD+80°481, HD 139813, HIP 75829, SAO 2558 | |
| Database references | |
| SIMBAD | π1 UMi AB |
| π1 UMi A | |
| π1 UMi B | |
Both stars are solar analogs and have been listed as possible members of the Hercules-Lyra association, one of the nearest moving groups to the Sun,[16] although this is now considered unlikely.[17] The primary, π1 Ursae Minoris A, has a mass 2% higher than the sun, an almost identical effective temperature at 5,771 K, a radius 98% of the sun's, and a bolometric luminosity 93% of the sun's. The secondary, π1 Ursae Minoris B, has a mass 92% of the sun's, a slightly lower temperature of 5,408 K, a radius 84% of the sun's, and a luminosity slightly over half of the sun.
References edit
- ^ a b c d van Leeuwen, F. (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, S2CID 18759600.
- ^ a b c d e f g Johnson, Harold L. (May 1953), "Photoelectric Observations of Visual Double Stars.", Astrophysical Journal, 117: 361, Bibcode:1953ApJ...117..361J, doi:10.1086/145700.
- ^ Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
- ^ Abt, H. A. (1981), "Visual multiples. VII - MK classifications", The Astrophysical Journal Supplement Series, 45: 437, Bibcode:1981ApJS...45..437A, doi:10.1086/190719.
- ^ a b de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
- ^ a b c d e 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.
- ^ Porto de Mello, G. F.; et al. (March 2014), "A photometric and spectroscopic survey of solar twin stars within 50 parsecs of the Sun; I. Atmospheric parameters and color similarity to the Sun", Astronomy and Astrophysics, 563: A52, arXiv:1312.7571, Bibcode:2014A&A...563A..52P, doi:10.1051/0004-6361/201322277, S2CID 119111150.
- ^ a b c d e 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.
- ^ a b c Tokovinin, Andrei (2014), "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs", The Astronomical Journal, 147 (4): 14, arXiv:1401.6827, Bibcode:2014AJ....147...87T, doi:10.1088/0004-6256/147/4/87, S2CID 56066740, 87.
- ^ a b c d Mishenina, T. V.; et al. (April 2013), "Abundances of neutron-capture elements in stars of the Galactic disk substructures", Astronomy & Astrophysics, 552: 12, arXiv:1303.1730, Bibcode:2013A&A...552A.128M, doi:10.1051/0004-6361/201220687, S2CID 119268097, A128.
- ^ a b Casagrande, L.; et al. (2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy & Astrophysics, 530 (A138): 21, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276, S2CID 56118016.
- ^ Pace, G. (March 2013), "Chromospheric activity as age indicator. An L-shaped chromospheric-activity versus age diagram", Astronomy & Astrophysics, 551: 4, arXiv:1301.5651, Bibcode:2013A&A...551L...8P, doi:10.1051/0004-6361/201220364, S2CID 56420519, L8.
- ^ "** STF 1972AB". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-26.
{{cite web}}: CS1 maint: postscript (link)- HD 139777 -- High proper-motion Star
- HD 139813 -- High proper-motion Star
- ^ Kepple, George Robert; Sanner, Glen W. (1998), The Night Sky Observers Guide: Spring & summer, vol. 2, Willmann-Bell, p. 418, ISBN 0943396603.
- ^ a b Lépine, Sébastien; Bongiorno, Bethany (March 2007), "New Distant Companions to Known Nearby Stars. II. Faint Companions of Hipparcos Stars and the Frequency of Wide Binary Systems", The Astronomical Journal, 133 (3): 889–905, arXiv:astro-ph/0610605, Bibcode:2007AJ....133..889L, doi:10.1086/510333, S2CID 16800796.
- ^ a b Eisenbeiss, T.; et al. (August 2013), "The Hercules-Lyra association revisited. New age estimation and multiplicity study" (PDF), Astronomy & Astrophysics, 556: 19, arXiv:1312.4045, Bibcode:2013A&A...556A..53E, doi:10.1051/0004-6361/201118362, S2CID 119275785, A53.[permanent dead link]
- ^ Lopez-Santiago, J.; Montes, D.; Crespo-Chacon, I.; Fernandez-Figueroa, M. J. (2006), "The Nearest Young Moving Groups", The Astrophysical Journal, 643 (2): 1160–1165, arXiv:astro-ph/0601573, Bibcode:2006ApJ...643.1160L, doi:10.1086/503183, S2CID 119520529.
External links edit
- The Electronic Sky
- University of Florida Astronomy Department
- HR 1971
- Image Omicron Aurigae