R Leonis
 Rendering of R Leonis's 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] |
| Characteristics | |
| Spectral type | M8IIIe |
| Apparent magnitude (J) | -0.7[2] |
| B−V color index | 1.26 |
| Variable type | Mira-type |
| Astrometry | |
| Distance | 370 ly (113.5 [3] pc) |
| Details | |
| 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, AG+11 1144, SAO 98769 | |
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?
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.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (unconfirmed) | ≥2 MJ | ≥2.7 | 1898 | 0 | — | — |
References
- ↑ "GCVS Query=R Leo". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2012-08-22.
- ↑ "V* R Leo". SIMBAD Astronomical Database. Retrieved 2012-08-21.
- 1 2 3 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. - 1 2 3 4 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/0411133. Bibcode:2005A&A...431.1019F. doi:10.1051/0004-6361:20042013.