Pi1 Ursae Minoris

For other stars with this Bayer designation, see π Ursae Minoris.
π1 Ursae Minoris
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Ursa Minor
π1 UMi A
Right ascension 15h 29m 11.18410s[1]
Declination +80° 26′ 54.9673″[1]
Apparent magnitude (V) +6.58[2]
π1 UMi B
Right ascension 15h 29m 23.59182s[3]
Declination +80° 27′ 00.9654″[3]
Apparent magnitude (V) +7.31[2]
Characteristics
π1 UMi A
Evolutionary stage main sequence[1]
Spectral type G1.5 V(n)[4]
U−B color index +0.13[2]
B−V color index +0.67[2]
π1 UMi B
Evolutionary stage main sequence[3]
Spectral type G9 V[5]
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[6] km/s
Proper motion (μ) RA: −225.796[1] mas/yr
Dec.: +107.613[1] mas/yr
Parallax (π)45.8428±0.0203 mas[1]
Distance71.15 ± 0.03 ly
(21.814 ± 0.010 pc)
Absolute magnitude (MV)4.94±0.04[7]
π1 UMi B
Radial velocity (Rv)−15.40±0.70[6] km/s
Proper motion (μ) RA: −217.596[3] mas/yr
Dec.: +105.986[3] mas/yr
Parallax (π)45.8939±0.0163 mas[3]
Distance71.07 ± 0.03 ly
(21.789 ± 0.008 pc)
Details
π1 UMi A
Mass1.02[8] M☉
Radius0.96[9] R☉
Luminosity0.92[9] L☉
Surface gravity (log g)4.49[9] cgs
Temperature5,771[9] K
Metallicity [Fe/H]+0.22[10] dex
Rotation4.23 days[11]
Rotational velocity (v sin i)4.81[10] km/s
Age9.22±3.84[12] Gyr
π1 UMi B
Mass0.92[8] M☉
Radius0.84[9] R☉
Luminosity0.52[9] L☉
Surface gravity (log g)4.55[9] cgs
Temperature5,330[9] K
Metallicity [Fe/H]+0.01[10] dex
Rotation8 days[13]
Rotational velocity (v sin i)5.06[10] km/s
Age7.4[12] Gyr
Other designations
π1 UMi, ADS 9696, WDS J15292+8027[14]
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
SIMBADπ1 UMi AB
π1 UMi A
π1 UMi B

Pi1 Ursae Minoris[15] is a common proper motion binary star[16] 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,[16] which corresponds to a physical separation of about 680 AU,[17] and orbit each other with a period of about 13,100 years.[8]

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,[17] although this is now considered unlikely.[18] 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

  1. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ 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.
  3. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  4. ^ 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.
  5. ^ Abt, H. A. (1981), "Visual multiples. VII - MK classifications", The Astrophysical Journal Supplement Series, 45: 437, Bibcode:1981ApJS...45..437A, doi:10.1086/190719.
  6. ^ 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.
  7. ^ 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.
  8. ^ 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.
  9. ^ a b c d e f g h Stassun, Keivan G.; et al. (2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467.
  10. ^ a b c d Freckelton, Alix Violet; Mortier, Annelies; Bedell, Megan; Morrell, Sam; Naylor, Tim; Buchhave, Lars A.; Davies, Guy R.; González Hernández, J. I.; Klein, Baptiste; De Mooij, Ernst J. W.; Passegger, Vera Maria; Quirrenbach, Andreas; Roy, Arpita; Santos, Nuno C.; Sousa, Sérgio G.; Suárez Mascareño, A.; Tsantaki, Maria; Zhao, Lily L. (2025). "Gr8stars ─ I. A homogeneous spectroscopic study of bright FGKM dwarfs and a public library of their high-resolution spectra". Monthly Notices of the Royal Astronomical Society. 540 (2): 1786. arXiv:2505.12945. Bibcode:2025MNRAS.540.1786F. doi:10.1093/mnras/staf825.
  11. ^ Colman, Isabel L.; Angus, Ruth; David, Trevor; Curtis, Jason; Hattori, Soichiro; Lu, Yuxi (Lucy) (2024). "Methods for the Detection of Stellar Rotation Periods in Individual TESS Sectors and Results from the Prime Mission". The Astronomical Journal. 167 (5): 189. arXiv:2402.14954. Bibcode:2024AJ....167..189C. doi:10.3847/1538-3881/ad2c86.
  12. ^ a b 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.
  13. ^ Isaacson, Howard; Fischer, Debra (2010). "Chromospheric Activity and Jitter Measurements for 2630 Stars on the California Planet Search". The Astrophysical Journal. 725 (1): 875. arXiv:1009.2301. Bibcode:2010ApJ...725..875I. doi:10.1088/0004-637X/725/1/875.
  14. ^ "** STF 1972AB". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-26.{{cite web}}: CS1 maint: postscript (link)
  15. ^ Kepple, George Robert; Sanner, Glen W. (1998), The Night Sky Observers Guide: Spring & summer, vol. 2, Willmann-Bell, p. 418, ISBN 0943396603.
  16. ^ 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.
  17. ^ 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.
  18. ^ 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.
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