Gliese 777
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| Observation data Epoch J2000.0 |
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|---|---|
| Constellation (pronunciation) |
Cygnus |
| Right ascension | 20h 03m 37.41s / 20h 3m 26.75s |
| Declination | +29° 53′ 48.50″ / +29° 51′ 58.8″ |
| Apparent magnitude (V) | +5.71 / +14.40 |
| Characteristics | |
| Spectral type | G6IV / M4.5V |
| U-B color index | ? |
| B-V color index | ? |
| Variable type | none / ? |
| 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 / ? |
| Rotation | ? |
| Age | 6700 million / ? years |
| Other designations | |
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BD+29°3872 A, HR 7670, HD 190360, HIP 98767
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Gliese 777 (Gl 777) is a 6th magnitude star in the constellation Cygnus. The system is a binary. The primary component is a yellow subgiant and the secondary component is a red dwarf. The primary component is visible to the unaided eye under very good conditions.
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[edit] Gliese 777 A
Gliese 777 A 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.
As of 2005 two extrasolar planets are known to be orbiting Gliese 777 A.
[edit] Planetary system
In 2002 a discovery of long-period, wide-orbiting planet Gliese 777 Ab was announced by Michel Mayor. The planet orbited in circular path (e=0.08) 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 (e=0.01).
| Companion (in order from star) |
Mass (MJ) |
Orbital period (days) |
Semimajor axis (AU) |
Eccentricity |
|---|---|---|---|---|
| c | >0.057 ± 0.19 | 17.1 ± 0.015 | 0.128 ± 0.002 | 0.01 ± 0.1 |
| b | >1.502 ± 0.13 | 2891 ± 85 | 3.92 ± 0.17 | 0.36 ± 0.03 |
[edit] Gliese 777 B
Gliese 777 B is a distant, dim red dwarf star orbiting the primary at a distance of 3000 AU. 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.
[edit] METI message to Gliese 777
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 2051. [1]
[edit] See also
[edit] 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" (abstract). Astronomy & Astrophysics 426: 353 – 365. doi:.
- 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" (abstract). Astronomy and Astrophysics 410: 1051-1054.
- Vogt et al. (2005). "Five New Multicomponent Planetary Systems". The Astrophysical Journal 632 (1): 638 – 658. doi:.
[edit] External links
- SIMBAD: HD 190360 --High proper-motion Star (Gl 777 A) + LHS 3509 (Gl 777 B)
- Extrasolar Planets Encyclopaedia: HD 190360
- Extrasolar Visions: Gliese 777 A + Gliese 777 Ac + Gliese 777 Ab
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