R Leonis
 Rendering of R Leonis's evaporating planetary companion |
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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|---|---|
| Constellation | Leo |
| Right ascension | 09h 47m 33.4904s |
| Declination | +11° 25′ 43.646″ |
| Apparent magnitude (V) | 6.02 |
| Characteristics | |
| Spectral type | M8IIIe |
| B−V color index | 1.26 |
| Variable type | Mira-type |
| Astrometry | |
| Distance | 370 ly (113.5 [1] pc) |
| Details | |
| Mass | 0.7 [1] M☉ |
| Radius | 320-350[2] R☉ |
| Luminosity | 8090[2] L☉ |
| Temperature | 2930-3080[2] K |
| Other designations | |
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R Leo, HIP 48036, HD 84748 ,HR 3882, BD+12 2096, AG+11 1144, SAO 98769
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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 2930 and 3080 kelvins and radius spans between 320 and 350 solar radii[2] (as large as 1.36–1.5 astronomical units, roughly Mars's orbital zone).
[edit] A planetary system?
In 2009 Wiesemeyer et al.[1] 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 1500 kelvins, accounting a stellar luminosity of more than 8,000 times that of the Sun.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| b (unconfirmed) | ≥2 MJ | ≥2.7 | 1898 | 0 |
[edit] References
- ^ 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:0809.0359. Bibcode 2009A&A...498..801W. doi:10.1051/0004-6361/200811242.
- ^ a b c d Fedeleet al. (2005). "The K -Band Intensity Profile of R Leonis Probed by VLTI/VINCI". Astronomy and Astrophysics 431 (3): 1019–1026. arXiv:astro-ph/0411133. Bibcode 2005A&A...431.1019F. doi:10.1051/0004-6361:20042013.
[edit] External links
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