Upsilon Ursae Majoris

Upsilon Ursae Majoris
Location of υ Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ursa Major
Right ascension 09h 50m 59.35700s[1]
Declination +59° 02′ 19.4486″[1]
Apparent magnitude (V) 3.68 – 3.86[2]
Characteristics
Spectral type F2 IV[3]
U−B color index +0.09[4]
B−V color index +0.29[4]
Variable type δ Sct[2]
Astrometry
Radial velocity (Rv)27.3±4.1[5] km/s
Proper motion (μ) RA: +42.97[1] mas/yr
Dec.: −23.62[1] mas/yr
Parallax (π)28.06 ± 0.20 mas[1]
Distance116.2 ± 0.8 ly
(35.6 ± 0.3 pc)
Absolute magnitude (MV)+1.11[6]
Details
υ UMa A
Mass1.57[7] or 2.20[3] M☉
Radius2.79±0.40[8] R☉
Luminosity29.5[9] L☉
Surface gravity (log g)3.79±0.14[7] cgs
Temperature7,211±245[7] K
Rotation1.2±0.30 d[8]
Rotational velocity (v sin i)124.2[10] km/s
Age1.168[7] Gyr
υ UMa B
Mass0.44[3] M☉
Other designations
υ UMa, WDS J09510+5902[11]
A: 29 Ursae Majoris, BD+59°1268, FK5 368, HD 84999, HIP 48319, HR 3888, SAO 27401[11]
Database references
SIMBADdata

Upsilon Ursae Majoris, Latinized from υ Ursae Majoris, is a binary star[12] in the northern circumpolar constellation of Ursa Major. It is visible to the naked eye with an apparent visual magnitude of +3.79.[4] Based upon an annual parallax shift of 13.24 mas,[1] it is located roughly 246 light-years from the Sun.

A light curve for Upsilon Ursae Majoris, plotted from TESS data[13]

The primary member of the system, component A, is an F-type subgiant star. It is a Delta Scuti variable[8] with a period of 0.1327 day and an amplitude of 0.050 magnitude.[14] With an estimated age of 1.168[7] billion years, it is spinning rapidly with a projected rotational velocity of 124.2 km/s[10] and a rotation period of 1.2 days.[8] The star has about 1.57[7] times the mass of the Sun and 2.79[8] times the Sun's radius. (De Rosa and colleagues give a mass estimate of 2.2[3] times the Sun's mass.) It is radiating around 29.5[9] times the solar luminosity from its outer atmosphere at an effective temperature of 7,211 K.[7]

The companion, component B, is a magnitude +11.0 star.[12] As of 2008, it has an angular separation of 11.78 arcseconds along a position angle of 295.4°. This corresponds to a projected separation of 419.8 AU.[3] It has a mass around 40% that of the Sun.[3]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference DeRosa2014 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference vonEiff2012 was invoked but never defined (see the help page).
  7. ^ a b c d e f g Cite error: The named reference David2015 was invoked but never defined (see the help page).
  8. ^ a b c d e Cite error: The named reference Korzennik1995 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Balona1999 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Schroeder2009 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Rodriguez2000 was invoked but never defined (see the help page).