R Leonis

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R Leonis
R Leonis evaporating planet.png

Rendering of R Leonis's putative evaporating planetary companion
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Leo
Right ascension 09h 47m 33.4904s
Declination +11° 25′ 43.646″
Apparent magnitude (V) 4.4 - 11.3[1]
Spectral type M8IIIe
Apparent magnitude (J) -0.7[2]
B−V color index 1.26
Variable type Mira-type
Distance 370 ly
(113.5 [3] pc)
Mass 0.7[3] M
Radius 320-350[4] R
Luminosity 8,090[4] L
Temperature 2,930-3,080[4] K
Other designations
R Leo, HIP 48036, HD 84748, HR 3882, BD+12° 2096, SAO 98769
Database references

R Leonis is a red giant Mira-type variable star in the constellation Leo.

The apparent magnitude of R Leonis varies between 4.31 and 11.65 with a period of 312 days. At maximum it can be seen with the naked eye, while at minimum a telescope of at least 7 cm is needed. The star's effective temperature is estimated between 2,930 and 3,080 kelvins and radius spans between 320 and 350 solar radii[4] (as large as 1.36–1.5 astronomical units, roughly Mars's orbital zone).

A planetary system?[edit]

In 2009 Wiesemeyer et al.[3] proposed that quasi-periodic fluctuations observed for the star R Leonis may be due to the presence of an evaporating substellar companion, probably an extrasolar planet. They have inferred a putative mass for the orbiting body of twice the mass of Jupiter, orbital period of 5.2 years and likely orbital separation of 2.7–3 astronomical units. If confirmed such a planetary object could likely be an evaporating planet, with long comet-like trail as hinted by intense SiO maser emissions. Planetary temperature would exceed 1,500 kelvins, accounting a stellar luminosity of more than 8,000 times that of the Sun.

The R Leonis planetary system
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b (unconfirmed) ≥2 MJ ≥2.7 1898 0


  1. ^ "GCVS Query=R Leo". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2012-08-22. 
  2. ^ "V* R Leo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-08-21. 
  3. ^ a b c Wiesemeyer; et al. (2009). "Precessing planetary magnetospheres in SiO stars?. First detection of quasi-periodic polarization fluctuations in R Leonis and V Camelopardalis". Astronomy and Astrophysics. 498 (3): 801–810. arXiv:0809.0359Freely accessible. Bibcode:2009A&A...498..801W. doi:10.1051/0004-6361/200811242. 
  4. ^ a b c d Fedele; et al. (2005). "The K -Band Intensity Profile of R Leonis Probed by VLTI/VINCI". Astronomy and Astrophysics. 431 (3): 1019–1026. arXiv:astro-ph/0411133Freely accessible. Bibcode:2005A&A...431.1019F. doi:10.1051/0004-6361:20042013. 

External links[edit]