Gliese 570
From Wikipedia, the free encyclopedia
 GJ 570 D looking at star A (right) and BC (left) |
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| Observation data Equinox J2000.0 |
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|---|---|
| Constellation | Libra |
| Right ascension | 14h 57m 28.0/27.2s |
| Declination | -21° 24' 55/56" |
| Apparent magnitude (V) | 5.64 / ? / 9.90 |
| Characteristics | |
| Spectral type | K4V / M1V / M3V / T7V |
| U-B color index | 1.06 /1.22 /? |
| B-V color index | 1.11 / 1.51 / ? |
| Variable type | not / ? |
| Astrometry | |
| Radial velocity (Rv) | +27.9 km/s |
| Proper motion (μ) | RA: 1034.18 mas/yr Dec.: -1725.60 mas/yr |
| Parallax (π) | 169.85 ± 0.82 mas |
| Distance | 19.2 ± 0.09 ly (5.89 ± 0.03 pc) |
| Absolute magnitude (MV) | 6.79 / ? / 11.05 |
| Details | |
| Mass | 0.76 / 0.55 / 0.35 M☉ |
| Radius | 0.77 / 0.65 / ? R☉ |
| Luminosity | 0.16 / 0.02 / 0.003 L☉ |
| Temperature | 4170 / 2700 / ? K |
| Metallicity | 102% |
| Rotation | ? |
| Age | ? years |
| Other designations | |
Gliese 570 (also known as HR 5568) is a trinary star about 19.2 light-years away in the constellation Libra. The system consists of an orange dwarf primary, a binary star set of red dwarfs, and a far out brown dwarf. The system is located southwest of Alpha Librae.
In the 1990s, the European Hipparcos satellite mission measured a parallax for the close binary stars B and C that suggested a distance of 24.4 light-year from the sun with about five light-years farther than the estimated distance to Star A. Earth-based parallax and orbit observations made over a longer time frame, however, suggest that the two stars are actually bound to Star A and so must actually lie at the same distance from the Sun. On January 15, 2000, astronomers announced the discovery of a cool methane brown dwarf in a wide orbit.
According to the new Sixth Catalog of Orbits of visual binaries, Star A and the close binary pair BC have a wide average separation of about 190 AUs, moving in an eccentric orbit (e=0.20) that lasts some 2,130 years and is inclined from the perspective of an observer on Earth at 72.53°. The triple star system is said to exhibit moderate chromospheric activity. It has a galactic motion (eccentricity of 0.195 and inclination of sin i = 0.553) that is consistent with an assignation to the old disk population.
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[edit] Gliese 570 A
Gliese 570 A is the primary star in the system. This orange dwarf may have just over three fourths (76 percent) of the sun's mass, about 77 percent of its diameter, only 15.6 percent of its luminosity, and a rotational period of 48.3 days. The star appears to be as enriched (102 percent) as the Sun with elements heavier than hydrogen ("metallicity"), based on its abundance of iron.
[edit] Planet
[edit] Gliese 570 Ab
| Orbital elements | ||
|---|---|---|
| Semi-major axis a: | 1 AU | |
| Eccentricity e: | 0 | |
| Orbital period P: | 400 d | |
| Inclination i: | ?° | |
| Longitude of periastron ω: |
?° | |
| Time of periastron τ: | ? JD | |
| Physical characteristics | ||
| Mass: | 0.75 MJ | |
| Radius: | 0.971 RJ | |
| Density: | ? kg/m³ | |
| Temperature: | 171 K | |
| Discovery | ||
| Discovery date: | 1998 | |
| Detection method(s): | Doppler Spectroscopy | |
| Discoverer(s): | Kürster et al. | |
Gliese 570 Ab is an extrasolar planet orbiting Gliese 570 A. The planet was hypothesised by Martin Kürster in 1998. This planet isn't confirmed.
[edit] Gliese 570 BC
Gliese 570 BC are a set of red dwarfs orbiting each other around the primary star. The pair orbit star A at about 109 AUs with a 2,130 year orbit. Star B orbits about 0.31 AUs from the BC center and C orbits 0.48 AUs from the BC center and they orbit each other every 0.846 years.
[edit] Gliese 570 D
Gliese 570 D is the farthest object in the system. This brown dwarf (T-dwarf) was discovered on January 15, 2000 by astronomers at the Infrared Processing and Analysis Center (IPAC) on the Caltech campus in Pasadena, California. GJ 570 D was observed at a wide separation of more than 1,500 AUs from the primary. It has an estimated mass of 50 Jupiters.
The status of GJ 570 D as a methane brown dwarf was confirmed by taking its spectral fingerprint with the 4-meter telescope at the Cerro Tololo Interamerican Observatory in Chile. Found as one of 12 objects discovered since 1995 in the 2-Micron All Sky Survey, the surface temperature of this substellar object was found to be a relatively cool 900°F, compared with the Sun's 10,000°F. GJ 570 D is significantly cooler (by 160° K) and less luminous than any other known brown dwarf, including the prototype T-dwarf, Gliese 229 b. Classed as T7-8V, it is estimated to be between two and five billion years old.
[edit] Other resources
[edit] See also
[edit] External links
- SolStation: Gliese 570 / HR 5568 ABC
- SolStation: Gl 570 / HR 5568 ABC (orbit)
- Extrasolar Visions: HR 5568 A
- Extrasolar Visions: HR 5568 Ab
