Nu Ursae Majoris

Nu Ursae Majoris
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings

Location of ν Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ursa Major
Right ascension 11h 18m 28.73720s[1]
Declination +33° 05′ 39.5109″[1]
Apparent magnitude (V) +3.490[2]
Characteristics
Spectral type K3 III[3]
U−B color index +1.550[2]
B−V color index +1.400[2]
Astrometry
Radial velocity (Rv)-9.63 ± 0.38[4] km/s
Proper motion (μ) RA: −26.139 mas/yr[1]
Dec.: 27.892 mas/yr[1]
Parallax (π)8.17 ± 0.17 mas[5]
Distance399 ± 8 ly
(122 ± 3 pc)
Absolute magnitude (MV)−2.47 ± 0.16[6]
Details
Mass3.82±0.23[7] M☉
Radius60+1.24
−1.29[7] R☉
Luminosity1242±81[7] L☉
Surface gravity (log g)1.89[6] cgs
Temperature4,422±26[7] K
Metallicity [Fe/H]–0.04[6] dex
Rotational velocity (v sin i)10[8] km/s
Age200±30[7] Myr
Other designations
Alula Borealis, ν Ursae Majoris, ν UMa, Nu UMa, 54 Ursae Majoris, BD+33 2098, CCDM J11185+3306A, FK5 425, GC 15547, HD 98262, HIP 55219, HR 4377, IDS 11131+3338 A, PPM 75790, SAO 62486, WDS J11185+3306A [9]
Database references
SIMBADdata

Nu Ursae Majoris (ν Ursae Majoris, abbreviated Nu UMa, ν UMa), formally named Alula Borealis /əˈluːlə bɒriˈælɪs/,[10][11] is a double star in the northern circumpolar constellation of Ursa Major. At an apparent visual magnitude of +3.490,[2] it is bright enough to be seen with the naked eye. Based upon parallax measurements, the distance to ν Ursae Majoris is about 399 light-years (122 parsecs).[5] At such distance, its apparent brightness is diminished by 0.48 magnitudes due to interveining gas and dust.[7]

This is a giant star with a stellar classification of K3 III.[3] Being 200 million years old, it has expanded to about 60 times the radius of the Sun and is radiating 1240 times the Sun's luminosity. The effective temperature of the outer envelope is 4,422 K;[7] cool enough to give it an orange hue typical of a K-type star.[12] It has a 10th-magnitude optical companion at an angular separation of 7.1 arcseconds.

  1. ^ a b c Cite error: The named reference DR3 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference mnras172_667 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference araa11_29 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference aaa430_165 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference aaa526_A100 was invoked but never defined (see the help page).
  7. ^ a b c d e f g Cite error: The named reference baines was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference csrv239_1 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  11. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  12. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).