| content | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 03m 37.41s |
| Declination | +29° 53′ 48.50″ |
| Apparent magnitude (V) | +5.71 / +14.40 |
| Characteristics | |
| Spectral type | G6IV / M4.5V |
| B-V color index | 0.749 |
| Astrometry | |
| Radial velocity (Rv) | -45.3 km/s |
| Proper motion (μ) | RA: 683.35 / 682 mas/yr Dec.: -524.10 / -530 mas/yr |
| Parallax (π) | 62.92 / 56 ± .51 .42 171 mas |
| Distance | 51.81 ly (15.89 pc) |
| Absolute magnitude (MV) | +4.70 / +13.39 |
| Details | |
| Mass | 0.9 M☉ |
| Radius | 1.2 R☉ |
| Luminosity | 1.11 L☉ |
| Temperature | 5417 K |
| Metallicity | 1.38 × solar |
| Age | 6700 million years |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gliese 777, often abbreviated as Gl 777 and or GJ 777, is a yellow subgiant approximately 52 light-years away in the constellation of Cygnus. The system is also a binary star system made up of two stars and possibly a third. As of 2005, two extrasolar planets are known to orbit the primary star.
Contents |
Stellar components
The primary star of the system (cataloged as Gliese 777A) is a yellow subgiant, a Sun-like star that is ceasing fusing hydrogen in its core. The star is much older than the Sun being about 6700 million years old. It is 4% less massive than the Sun. It is also rather metal-rich having about 70% more "metals" (elements heavier than helium) than the Sun, which is typical to stars with extrasolar planets.
The secondary star (Gliese 777B) is a distant, dim red dwarf star orbiting the primary at a distance of 3,000 astronomical units. One orbit takes at least tens of thousands of years to complete. The star itself may be a binary, the secondary being a very dim red dwarf. Not much information is available on the star system.
Planetary system
In 2002 a discovery of a long-period, wide-orbiting planet (Gliese 777b) was announced by Michel Mayor. The planet orbited in circular path and the orbital eccentricity was increased in later measurements (e=0.36). The planet was "Jupiter-twin" and was turned to "eccentric Jupiter" with mass about 1.5 times Jupiter and about the same size. In 2005 further observation of the star show another amplitude with a period of 17.1 days. This indicates one of the smallest discovered planet at the time. The mass was only 18 time more than Earth or about same as Neptune with very low eccentricity. There was a METI message sent to Gliese 777. It was transmitted from Eurasia's largest radar — 70-meter Eupatoria Planetary Radar. The message was named Cosmic Call 1, it was sent on July 1 1999, and it will arrive at Gliese 777 in April of 2051.1
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| c | >0.057 ± 0.19 MJ | 0.128 ± 0.002 | 17.1 ± 0.015 | 0.01 ± 0.1 |
| b | >1.502 ± 0.13 MJ | 3.92 ± 0.17 | 2891 ± 85 | 0.36 ± 0.03 |
See also
References
- N. Asghari et al. (2004). "Stability of terrestrial planets in the habitable zone of Gl 777 A, HD 72659, Gl 614, 47 Uma and HD 4208". Astronomy & Astrophysics 426 (1): 353–365. doi:, http://www.aanda.org/articles/aa/full/2004/40/aa0390-04/aa0390-04.html.
- Naef et al. (2003). "The ELODIE survey for northern extra-solar planets II. A Jovian planet on a long-period orbit around GJ 777 A". Astronomy and Astrophysics 410 (3): 1051–1054. doi:, http://www.aanda.org/articles/aa/full/2003/42/aa4076/aa4076.html.
- Vogt et al. (2005). "Five New Multicomponent Planetary Systems". The Astrophysical Journal 632 (1): 638–658. doi:, http://www.journals.uchicago.edu/doi/full/10.1086/432901.
External links
- "Gliese 777A". Extrasolar Visions. Retrieved on 2008-07-02.
- "HD 190360". The Extrasolar Planets Encyclopaedia (2005-01-25). Retrieved on 2008-06-10.
- Extrasolar Planet Interactions by Rory Barnes & Richard Greenberg, Lunar and Planetary Lab, University of Arizona
