R Leonis
Variable star in the constellation Leo
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R Leonis is a red giant Mira-type variable star located approximately 370 light years away in the constellation Leo.
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Leo |
| Right ascension | 09h 47m 33.4840s[1] |
| Declination | +11° 25′ 43.823″[1] |
| Apparent magnitude (V) | 4.4 - 11.3[2] |
| Characteristics | |
| Spectral type | M6e-M8IIIe-M9.5e[2] |
| Apparent magnitude (J) | −0.7[3] |
| B−V color index | 1.26 |
| Variable type | Mira variable |
| Astrometry | |
| Proper motion (μ) | RA: 6.132[1] mas/yr Dec.: −53.097[1] mas/yr |
| Parallax (π) | 14.0566±0.8378 mas[1] |
| Distance | 372 ly (114[4] pc) |
| Details | |
| Mass | 0.7[5] M☉ |
| Radius | 320 – 350[6] R☉ |
| Luminosity | 3,537[4] L☉ |
| Temperature | 2,930 – 3,080[6] K |
| Other designations | |
| R Leo, AAVSO 0942+11, BD+12°2096, HD 84748, HIP 48036, HR 3882, SAO 98769 | |
| Database references | |
| SIMBAD | data |
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 to be 2,930 – 3,080 kelvins and radius spans 320 solar radii (220,000,000 kilometres; 1.5 astronomical units),[6] roughly Mars's orbital zone.
Possible planet
In 2009 Wiesemeyer et al.[5] 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 astronomical units. If confirmed such a planetary object could likely be an evaporating planet, with a long comet-like trail as hinted by intense SiO maser emissions.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (unconfirmed) | ≥2 MJ | ≥2.7 | 1898 | 0 | — | — |