The quaternary star system Gliese 570. The T-type methane brown dwarf Gliese 570D is indicated with an arrow. Credit: 2MASS | |
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Libra |
Right ascension | 14h 57m 28.00144s [1] |
Declination | −21° 24′ 55.7131″ [1] |
Apparent magnitude (V) | 5.75 / 8.07 / 10.5 |
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 | None |
Astrometry | |
A | |
Radial velocity (Rv) | +26.75±0.12 [2] km/s |
Proper motion (μ) | RA: 1031.472 mas/yr [2] Dec.: -1723.619 mas/yr [2] |
Parallax (π) | 169.8843 ± 0.0653 mas [2] |
Distance | 19.199 ± 0.007 ly (5.886 ± 0.002 pc) |
Absolute magnitude (MV) | 6.89 [3] |
BC | |
Radial velocity (Rv) | +25.9 [4] km/s |
Proper motion (μ) | RA: 961.78 [1] mas/yr Dec.: -1677.83 [1] mas/yr |
Parallax (π) | 168.77 ± 21.54 mas [1] |
Distance | approx. 19 ly (approx. 5.9 pc) |
Absolute magnitude (MV) | 9.19 [3] / 11.05 |
D | |
Proper motion (μ) | RA: 1038.08 [5] mas/yr Dec.: -1677.59 [5] mas/yr |
Parallax (π) | 169.30 ± 1.70 mas [6] |
Distance | 19.3 ± 0.2 ly (5.91 ± 0.06 pc) |
Absolute magnitude (MV) | 11.05[ citation needed ] |
Details | |
Mass | 0.802 ± 0.040 [7] / 0.55 / 0.35 / 0.05 M☉ |
Radius | 0.739 ± 0.019 [7] / 0.65 R☉ |
Luminosity (bolometric) | 0.22 [note 1] / 0.04 / ? / 3•10−6 [8] L☉ |
Luminosity (visual, LV) | 0.16 / 0.02 / 0.003 / ? L☉ |
Temperature | 4597 ± 101 [7] / 2700 K |
Metallicity | [7] |
Rotation | 48.3 days |
Rotational velocity (v sin i) | 1.50 [7] km/s |
Other designations | |
A: HR 5568, LAL 27173, HD 131977, BD-20°4125, LHS 387, LTT 5949, GCTP 3375.00, SAO 183040, FK5 1391, LFT 1161, LPM 551, Vys 726, HIP 73184 | |
BC: HD 131976, HIP 73182, LHS 386, LTT 5948, BD-20°4123, SAO 183039, LFT 1160, LPM 550 | |
D: 2MASS J14571496-2121477 | |
Database references | |
SIMBAD | A |
BC | |
D | |
Exoplanet Archive | data |
ARICNS | data |
Gliese 570 (or 33 G. Librae) is a quaternary star system approximately 19 light-years away. The primary star is an orange dwarf star (much dimmer and smaller than the Sun). The other secondary stars are themselves a binary system, two red dwarfs that orbit the primary star. A brown dwarf has been confirmed to be orbiting in the system. In 1998, an extrasolar planet was thought to orbit the primary star, but it was discounted in 2000.
In the night sky, the Gliese 570 system lies in the southwestern part of Libra. The system is southwest of Alpha Librae and northwest of Sigma Librae. In the early 1990s, the European Hipparcos mission measured the parallax of components B and C, suggesting that the system was at a distance of 24.4 light-years from the Sun. This, however, was a relatively large error as Earth-based parallax and orbit observations suggest that the two stars are actually part of a system with Gliese 570 A, and must actually lie at the same distance.
The primary star of the system (component A) is an orange dwarf star that may just have over three fourths the mass of the Sun, about 77 percent of its radius, and only 15.6 percent of its visual luminosity. It has a separation of 190 astronomical units from the binary components B and C, moving in an eccentric orbit that takes at least 2130 years to complete. [9] Gliese 570 A is spectral type K4V and emits X-rays. [10] Radial velocities of the primary obtained in the course of an extrasolar planet search at Lick Observatory show a linear trend probably due to the orbital motion of the Gliese 570 BC system around the primary. [11]
A binary system in their own right, components B and C are both rather dim red dwarf stars that have less mass, radius, and luminosity than the Sun. Component B is spectral type M1V, component C is spectral type M3V, and both emit X-rays. [10]
On January 15, 2000, astronomers announced that they had found one of the coolest brown dwarfs then known. Catalogued as Gliese 570 D, it was observed at a wide separation of more than 1,500 astronomical unit from the triple star system. [12] It has an estimated mass of 50 times that of Jupiter.
The status of Gliese 570 D as a brown dwarf was confirmed by Doppler spectroscopy at the Cerro Tololo Interamerican Observatory in Chile. The surface temperature of this substellar object was found to be a relatively cool 500 degrees Celsius, making it cooler and less luminous than any other then-known brown dwarf (including the prototype "T" dwarf), and classifying the object as a T7-8V brown dwarf. No X-rays have been reported from this brown dwarf.
In 1998, an extrasolar planet was announced to orbit the primary star within the Gliese 570 system. The planet, identified as "Gliese 570 Ab", was considered doubtful and the claim was retracted in 2000. [13] No extrasolar planets have been confirmed to exist in this multiple star system thus far.
Gliese 876 is a red dwarf approximately 15 light-years away from Earth in the constellation of Aquarius. It is one of the closest known stars to the Sun confirmed to possess a planetary system with more than two planets, after Gliese 1061, YZ Ceti, Tau Ceti, and Luyten's Star; as of 2018, four extrasolar planets have been found to orbit the star. The planetary system is also notable for the orbital properties of its planets. It is the only known system of orbital companions to exhibit a near-triple conjunction in the rare phenomenon of Laplace resonance. It is also the first extrasolar system around a normal star with measured coplanarity. While planets b and c are located in the system's habitable zone, they are giant planets believed to be analogous to Jupiter.
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Gliese 412 is a pair of stars that share a common proper motion through space and are thought to form a binary star system. The pair have an angular separation of 31.4″ at a position angle of 126.1°. They are located 15.8 light-years distant from the Sun in the constellation Ursa Major. Both components are relatively dim red dwarf stars.
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Gliese 22, also catalogued V547 Cassiopeiae or ADS 440, is a hierarchical star system approximately 33 light-years away in the constellation of Cassiopeia. The system consists of pair of red dwarf stars, Gliese 22A and Gliese 22C, orbited by a third red dwarf Gliese 22B in an outer orbit of about 223 years.
Gliese 752 is a binary star system in the Aquila constellation. This system is relatively nearby, at a distance of about 19 light years.
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