Astronomy:Rho Ursae Majoris

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Short description: 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
12px
Location of ρ Ursae Majoris (circled)
Observation data
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[1] mas
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 often 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. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V. 
  2. ↑ 2.0 2.1 2.2 2.3 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. ↑ 3.0 3.1 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, doi:10.1051/0004-6361:20030647, Bibcode: 2003A&A...406..995M. 
  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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D. 
  5. ↑ 5.0 5.1 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, doi:10.1051/0004-6361:20041272, Bibcode: 2005A&A...430..165F. 
  6. ↑ 6.0 6.1 Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1, https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41.  The radius (R*) is given by:
    2⋅R*=(96.4⋅5.64⋅10−3) AU0.0046491 AU/R⨀≈116.9⋅R⨀
  7. ↑ 7.0 7.1 7.2 McDonald, I. et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–57, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M. 
  8. ↑ "rho UMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=rho+UMa. 
  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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  10. ↑ Eggen, O. J. (1992), "Asymptotic giant branch stars near the sun", The Astronomical Journal 104: 275, doi:10.1086/116239, Bibcode: 1992AJ....104..275E. 
  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, doi:10.1086/133420, Bibcode: 1994PASP..106..611P. 
  12. ↑ Richichi, A. et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics 431 (2): 773–777, doi:10.1051/0004-6361:20042039, Bibcode: 2005A&A...431..773R. 
  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, Jet Propulsion Laboratory, California Institute of Technology, https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720005197_1972005197.pdf. 
  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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