| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Leo |
| Right ascension | 11h 24m 17.359s[1] |
| Declination | –01° 31′ 44.67″[1] |
| Apparent magnitude (V) | +9.10[2] |
| Characteristics | |
| Spectral type | G8/K0IV[3] |
| B−Vcolor index | 0.874±0.002[2] |
| Astrometry | |
| Radial velocity (Rv) | +33.060±0.0025[4] km/s |
| Proper motion (μ) | RA: −178.689mas/yr[1] Dec.: −159.528mas/yr[1] |
| Parallax (π) | 18.178±0.017 mas[1] |
| Distance | 179.4 ± 0.2 ly (55.01 ± 0.05 pc) |
| Absolute magnitude (MV) | 5.62[2] |
| Details | |
| Mass | 0.93±0.02[5] M☉ |
| Radius | 0.90±0.03[5] R☉ |
| Luminosity | 0.56±0.02[5] L☉ |
| Surface gravity (log g) | 4.49±0.03[5] cgs |
| Temperature | 5,270±24[5] K |
| Metallicity [Fe/H] | 0.315±0.030[6] dex |
| Rotational velocity (v sin i) | 1.86±0.50[6] km/s |
| Age | 6±3 Gyr[5] ≥ 12.2[7] Gyr |
| Other designations | |
| Shama,BD−00°2437,HD 99109,HIP 55664,SAO 138182[8] | |
| Database references | |
| SIMBAD | data |
HD 99109 is an orange-huedstar with anexoplanetary companion in theconstellation ofLeo. It has anabsolute visual magnitude of +9.10,[2] which is too faint to be visible to the naked eye. The distance to this system is 179 light-years based onparallax, and it is drifting further away with aradial velocity of +33 km/s.[1] The star is one and half degrees away from thecelestial equator to the south.
Thestellar classification of this star is G8/K0IV,[3] matching alate G orearlyK-typesubgiant star. It appears to be past the end of itsmain sequence lifetime, having exhausted the supply of hydrogen at itscore.[7] The star is 93% as massive as the Sun and has 90% of the Sun's radius.[5] It is spinning with aprojected rotational velocity of ~2 km/s[6] and has over twice the abundance ofiron relative tohydrogen than the Sun. The star is radiating 56% of the Sun's luminosity from itsphotosphere at aneffective temperature of 5,270 K.[5] As of 2006, oneextrasolar planet has been confirmed to be orbiting the star.[6]
The star HD 99109 is namedShama. The name was selected in theNameExoWorlds campaign byPakistan, during the 100th anniversary of theIAU. Shama (شمع) is anUrdu literary term meaning a smalllamp orflame. The exoplanet companion is calledPerwana, meaning 'moth' in Urdu, alluding to the eternal love of an object circling a source of light.[9][10]
The planet HD 99109 b has an orbit comparable in eccentricity to the planetMars in theSolar System but has a mass at least half that ofJupiter. Stability analysis reveals that Earth-size planets could have stable orbits in the planet'sTrojan points, located 60 degrees ahead and behind the planet's position in its orbit.[7]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Perwana | >0.502 ± 0.070 MJ | 1.105 ± 0.065 | 439.3 ± 5.6 | 0.09 ± 0.16 | — | — |
