R Horologii

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R Horologii
Horologium constellation map.png
R Horologii (R) in Horologium
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Horologium
Right ascension 02h 53m 52.77206s[1]
Declination −49° 53′ 22.7408″[1]
Apparent magnitude (V) +3.92
Spectral type M 5e–M 8eII/III
Variable type Mira variable
Radial velocity (Rv) +60 ± 4.4 km/s
Proper motion (μ) RA: 130.35 ± 0.74[1] mas/yr
Dec.: 34.22 ± 0.72[1] mas/yr
Parallax (π) 4.76 ± 0.97[1] mas
Distance approx. 700 ly
(approx. 210 pc)
Other designations
HD 18242, HIP 13502, HR 868, CD−50° 860[2]
Database references

R Horologii (also known as HD 18242) is a red giant star approximately 700 light-years away in the constellation Horologium.[1] It is also a Mira variable with a period of 404.83 days,[3] and ranging from apparent magnitude 4.7 to 14.3—one of the largest ranges in brightness known.[4]


  1. ^ a b c d e f van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–64. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ "R Horologii". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 March 2016. 
  3. ^ Templeton, M. R.; Mattei, J. A.; Willson, L. A. (2005). "Secular Evolution in Mira Variable Pulsations". The Astronomical Journal. 130 (2): 776. arXiv:astro-ph/0504527Freely accessible. Bibcode:2005AJ....130..776T. doi:10.1086/431740. 
  4. ^ Privett, Grant; Jones, Kevin (2013). The Constellation Observing Atlas. New York, New York: Springer Science & Business Media. p. 102. ISBN 9781461476481. 

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