Rho Boötis

ρ Boötis
Diagram showing star positions and boundaries of the Boötes constellation and its surroundings
Location of ρ Boötes (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension 14h 31m 49.78962s[1]
Declination +30° 22′ 17.1781″[1]
Apparent magnitude (V) 3.59[2]
Characteristics
Spectral type K4 III[3]
U−B color index +1.44[2]
B−V color index +1.30[2]
R−I color index 0.65
Astrometry
Radial velocity (Rv)−13.57±0.19[4] km/s
Proper motion (μ) RA: –100.90[1] mas/yr
Dec.: +120.73[1] mas/yr
Parallax (π)20.37 ± 0.18[1] mas
Distance160 ± 1 ly
(49.1 ± 0.4 pc)
Absolute magnitude (MV)+0.27[3]
Details
Mass1.0–1.4[5] M☉
Radius21.57±0.25[5] R☉
Luminosity131.9±6.8[5] L☉
Surface gravity (log g)1.85±0.05[6] cgs
Temperature4,298±56[5] K
Metallicity [Fe/H]−0.19±0.10 [6] dex
Age10.11±2.82[6] Gyr
Other designations
ρ Boo, 25 Boötis, BD+31° 2628, FK5 534, HD 127665, HIP 71053, HR 5429, SAO 64202
Database references
SIMBADdata
ρ Boötis in optical light

Rho Boötis, Latinized from ρ Boötis, is a single,[7] orange-hued star in the northern constellation of Boötes. It is visible to the naked eye with an apparent visual magnitude of 3.59.[2] Based upon parallax measurements, it is located at a distance of approximately 160 light-years (49 parsecs) from Earth. It is moving toward the Sun with a radial velocity of −13.6 km/s.[4] There is an optical companion, a magnitude 11.5 star, located 34.7 arcseconds away along a position angle of 345° (as of 2013).[8]

This is an evolved K-type giant star, currently on the red giant branch, with a stellar classification of K4 III[3] and an estimated age of 10[6] billion years. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[9] It has around 1.2[5] times the mass of the Sun and has expanded to 22[5] times the Sun's girth. The star is radiating 132[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of about 4,300 K.[5]

In Chinese, 梗河 (Gěng Hé), meaning Celestial Lance, refers to an asterism consisting of ρ Boötis, ε Boötis and σ Boötis.[10] Consequently, ρ Boötis itself is known as 梗河三 (Gěng Hé sān, English: the Third Star of Celestial Lance.)[11]

References

  1. 1 2 3 4 5 van Leeuwen, F. (November 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.
  2. 1 2 3 4 Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society, 172: 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
  3. 1 2 3 Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics, 430: 303–311, arXiv:astro-ph/0409683, Bibcode:2005A&A...430..303C, doi:10.1051/0004-6361:20041440.
  4. 1 2 Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
  5. 1 2 3 4 5 6 7 8 Berio, P.; et al. (November 2011), "Chromosphere of K giant stars. Geometrical extent and spatial structure detection", Astronomy & Astrophysics, 535: A59, arXiv:1109.5476, Bibcode:2011A&A...535A..59B, doi:10.1051/0004-6361/201117479.
  6. 1 2 3 4 Reffert, Sabine; et al. (2015), "Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity", Astronomy & Astrophysics, 574: A116, arXiv:1412.4634, Bibcode:2015A&A...574A.116R, doi:10.1051/0004-6361/201322360.
  7. ↑ 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.
  8. ↑ Mason, Brian D.; et al. (2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  9. ↑ Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society, 25: 1319, Bibcode:1993AAS...183.1710G, retrieved 2012-02-04
  10. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  11. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 29 日
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