Pi1 Ursae Minoris

For other stars with this Bayer designation, see π Ursae Minoris.
π1 Ursae Minoris
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]
Distance71.12 ± 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]
Distance71.21 ± 0.05 ly
(21.83 ± 0.02 pc)
Details
π1 UMi A
Mass1.02[9] M☉
Radius0.98[6] R☉
Luminosity0.929[6] L☉
Surface gravity (log g)4.40[10] cgs
Temperature5,771[10] K
Metallicity [Fe/H]−0.22[11] dex
Age9.22±3.84[12] Gyr
π1 UMi B
Mass0.92[9] M☉
Radius0.84[8] R☉
Luminosity0.520[8] L☉
Surface gravity (log g)4.50[10] cgs
Temperature5,408[10] K
Metallicity [Fe/H]−0.18[11] dex
Other designations
π1 UMi, ADS 9696, WDS J15292+8027[13]
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[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]

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.

  1. ^ a b c d Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e f g Cite error: The named reference Johnson1953 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Gray2006 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Abt1981 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  6. ^ a b c d e Cite error: The named reference dr2a was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference aaa563_A52 was invoked but never defined (see the help page).
  8. ^ a b c d e Cite error: The named reference dr2b was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Tokovinin2014 was invoked but never defined (see the help page).
  10. ^ a b c d Cite error: The named reference Mishenina2013 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference Casagrande2011 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Pace2013 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Kepple1998 was invoked but never defined (see the help page).
  15. ^ a b Cite error: The named reference Lepine2007 was invoked but never defined (see the help page).
  16. ^ a b Cite error: The named reference Eisenbeiss2013 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference MG was invoked but never defined (see the help page).