HD 100777
Star in the constellation Leo
From Wikipedia, the free encyclopedia
HD 100777 is a single[7] star with a planetary companion in the equatorial constellation of Leo.[8] With an apparent visual magnitude of 8.42 it is too faint to be viewed with the naked eye, although the absolute magnitude of 4.81 indicates it could be seen if it were just 33 ly (10 pc) away. The distance to the star is approximately 162 light-years based on parallax measurements.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Leo |
| Right ascension | 11h 35m 51.52322s[1] |
| Declination | −04° 45′ 20.5046″[1] |
| Apparent magnitude (V) | 8.42[2] |
| Characteristics | |
| Spectral type | G8V[3] |
| B−V color index | 0.76±0.02[2] |
| Astrometry | |
| Radial velocity (Rv) | 1.10±0.14[1] km/s |
| Proper motion (μ) | RA: −11.535 mas/yr[1] Dec.: 35.586 mas/yr[1] |
| Parallax (π) | 20.1590±0.0285 mas[1] |
| Distance | 161.8 ± 0.2 ly (49.61 ± 0.07 pc) |
| Absolute magnitude (MV) | 4.95[2] |
| Details[4] | |
| Mass | 1.032+0.042 −0.045 M☉ |
| Radius | 1.033+0.021 −0.018 R☉ |
| Luminosity | 0.946+0.003 −0.004[5] L☉ |
| Surface gravity (log g) | 4.402±0.265 cgs |
| Temperature | 5,611±42 K |
| Metallicity [Fe/H] | 0.330±0.096 dex |
| Rotational velocity (v sin i) | 1.676±0.230 km/s |
| Age | 4.78+2.20 −2.14 Gyr |
| Other designations | |
| Sagarmatha, BD–03°3147, HD 100777, HIP 56572, SAO 138288, TYC 4933-678-1, 2MASS J11355152-0445204[6] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
The International Astronomical Union held the NameExoWorlds campaign in 2019. Nepal named the star Sagarmatha, the Nepali name of Mount Everest, and the exoplanet revolving it was named as Laligurans, the Nepali name of the flower Rhododendron.[9]
This is an ordinary G-type main-sequence star with a stellar classification of G8V.[3] It has a similar mass, size, and luminosity to the Sun. The star is roughly five[4] billion years old with an inactive chromosphere[8] and is spinning with a projected rotational velocity of 1.7 km/s.[4] A 2015 survey ruled out the existence of any additional stellar companions at projected distances from 18 to 369 astronomical units.[7]
Planetary system
In 2007, a giant exoplanet companion was found using the radial velocity method. It is orbiting HD 100777 at a distance of 1.03 AU with a period of 384 days and an eccentricity (ovalness) of 0.36. The inclination of the orbital plane of this body is unknown, so only a lower limit on the mass can be determined. It has at least 1.16 times the mass of Jupiter.[8]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Laligurans | >1.16 ± 0.03 MJ | 1.03 ± 0.03 | 383.7 ± 1.2 | 0.36 ± 0.02 | — | — |