Rho Ursae Majoris

Solitary red giant star in the constellation Ursa Major
Rho Ursae Majoris
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Location of ρ Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ursa Major
Right ascension 09h 02m 32.69092s[1]
Declination +67° 37′ 46.6280″[1]
Apparent magnitude (V) 4.74[2]
Characteristics
Spectral type M3 III[3]
U−B color index +1.84[2]
B−V color index +1.56[2]
Astrometry
Radial velocity (Rv)4.75±0.19[4] km/s
Proper motion (μ) RA: −22.83[1] mas/yr
Dec.: +18.13[1] mas/yr
Parallax (π)10.37 ± 0.25 mas[1]
Distance315 ± 8 ly
(96 ± 2 pc)
Absolute magnitude (MV)+0.06[5]
Details
Radius58[6] R☉
Luminosity464[7] L☉
Temperature3,725[7] K
Other designations
ρ UMa, 8 Ursae Majoris, BD+68°551, FK5 338, HD 76827, HIP 44390, HR 3576, SAO 14742[8]
Database references
SIMBADdata

Rho Ursae Majoris (ρ UMa) is the Bayer designation for a solitary[9] star in the northern circumpolar constellation of Ursa Major. It is faintly visible to the naked eye with an apparent visual magnitude of 4.74.[2] The distance to this star, based upon an annual parallax shift of 10.37 mas,[1] is around 315 light years.

With a stellar classification of M3 III,[3] this is a red giant star on the asymptotic giant branch.[10] It is a suspected small amplitude variable.[11] The measured angular diameter of the star after correcting for limb darkening is 5.64±0.15 mas,[12] which, at the estimated distance of this star, yields a physical size of about 58 times the radius of the Sun.[6] It is radiating 464 times the solar luminosity from its outer atmosphere at an effective temperature of about 3,725 K.[7] Based upon its motion through space, there is a 60.6% chance that this star is a member of the Sirius stream.[5]

Naming

  • With π1, π2, σ1, σ2, A and d, it composed the Arabic asterism Al Ṭhibā᾽, the Gazelle.[13] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Ṭhibā were the title for seven stars : A as Althiba I, π1 as Althiba II, π2 as Althiba III, this star (ρ) as Althiba IV, σ1 as Althiba V, σ2 as Althiba VI, and d as Althiba VII[14]
  • In Chinese, 三師 (Sān Shī), meaning Three Top Instructors, refers to an asterism consisting of ρ Ursae Majoris and σ2 Ursae Majoris. Consequently, the Chinese name for ρ Ursae Majoris itself is 三師一 (Sān Shī yī, English: the First Star of Three Top Instructors.).[15]

References

  1. ^ a b c d e f 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.
  2. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. ^ a b Marrese, P. M.; et al. (August 2003), "High resolution spectroscopy over lambda lambda 8500-8750 Å for GAIA. IV. Extending the cool MK stars sample", Astronomy and Astrophysics, 406: 995–999, Bibcode:2003A&A...406..995M, doi:10.1051/0004-6361:20030647.
  4. ^ 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.
  5. ^ a b Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304.
  6. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
    2 ⋅ R ∗ = ( 96.4 ⋅ 5.64 ⋅ 10 − 3 )   AU 0.0046491   AU / R ⨀ ≈ 116.9 ⋅ R ⨀ {\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(96.4\cdot 5.64\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 116.9\cdot R_{\bigodot }\end{aligned}}}
  7. ^ a b c McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
  8. ^ "rho UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-02-25.{{cite web}}: CS1 maint: postscript (link)
  9. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  10. ^ Eggen, O. J. (1992), "Asymptotic giant branch stars near the sun", The Astronomical Journal, 104: 275, Bibcode:1992AJ....104..275E, doi:10.1086/116239.
  11. ^ Percy, J. R.; et al. (1994), "Photometric surveys of suspected small-amplitude red variables. III: An AAVSO photometric photometry survey", Astronomical Society of the Pacific, 106 (700): 611–615, Bibcode:1994PASP..106..611P, doi:10.1086/133420.
  12. ^ Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
  13. ^ Allen, Richard Hinckley (1899), Star-Names and Their Meanings, New York: G. E. Stechert, p. 444
  14. ^ Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), Jet Propulsion Laboratory, California Institute of Technology.
  15. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 16 日
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