Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Musca [2] |
Right ascension | 11h 45m 42.91694s [3] |
Declination | −64° 50′ 29.4620″ [3] |
Apparent magnitude (V) | 11.50 [4] |
Characteristics | |
Spectral type | DQ6 [5] |
U−B color index | -0.59 [4] |
B−V color index | +0.19 [4] |
Astrometry | |
Proper motion (μ) | RA: 2661.640 mas/yr [3] Dec.: -344.933 mas/yr [3] |
Parallax (π) | 215.6753 ± 0.0181 mas [3] |
Distance | 15.123 ± 0.001 ly (4.6366 ± 0.0004 pc) |
Details | |
Mass | 0.56 ± 0.08 [6] M☉ |
Radius | 0.01 R☉ |
Luminosity | 0.0005 [7] L☉ |
Surface gravity (log g) | 8.27 ± 0.05 [7] cgs |
Temperature | 8,500 ± 300 [7] K |
Age | (as white dwarf) [7] 1.44 Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Location of Gliese 440 in the constellation Musca |
Gliese 440, also known as LP 145-141 or LAWD 37, [4] is an isolated white dwarf located 15.1 light-years (4.6 parsecs ) from the Solar System in the constellation Musca. [16] It is the fourth closest known white dwarf to the Sun, after Sirius B, Procyon B, and van Maanen's star. [17]
Gliese 440 is known at least from 1917, when its proper motion was published by R. T. A. Innes and H. E. Wood in Volume 37 of Circular of the Union Observatory. [18] The corresponding designation is UO 37. [10] (Note: this designation is not unique for this star, that is all other stars, listed in the table in the Volume 37 of this Circular, also could be called by this name).
Gliese 440 may be a member of the Wolf 219 moving group, which has seven possible members. These stars share a similar motion through space, which may indicate a common origin. [19] This group has an estimated space velocity of 160 km/s and is following a highly eccentric orbit through the Milky Way galaxy. [20]
White dwarfs are no longer generating energy at their cores through nuclear fusion, and instead are steadily radiating away their remaining heat. Gliese 440 has a DQ spectral classification, indicating that it is a rare type of white dwarf which displays evidence of atomic or molecular carbon in its spectrum. [21]
In 2019, Gliese 440 was observed passing in front of a more distant star. The bending of starlight by the gravitational field of Gliese 440 observed by the Hubble Space Telescope allowed its mass to be directly measured. The estimated mass of Gliese 440 is 0.56±0.08 M☉, which fits the expected range of a white dwarf with a carbon-oxygen core. This measurement marked the first direct gravitational mass determination of a single white dwarf. [6]
Gliese 440 has only 56% of the Sun's mass, [6] but it is the remnant of a massive main-sequence star that had an estimated 4.4 solar masses. [22] While it was on the main sequence, it probably was a spectral class B star (in the range B4–B9). [23] Most of the star's original mass was shed after it passed into the asymptotic giant branch stage, just prior to becoming a white dwarf.
A survey with the Hubble Space Telescope revealed no visible orbiting companions, at least down to the limit of detection. [24] [5]
Its proximity, mass and temperature have led to it being considered a good candidate to look for Jupiter-like planets. Its relatively large mass and high temperature mean that the system is relatively short-lived and hence of more recent origin. [22]
Hipparcos-Gaia proper motion shows an anomaly that hints to the presence of an exoplanet that has a mass of either 0.44 or 0.60 MJ which is between Saturn and Jupiter. [25] [26]
Gliese 570 is a quaternary star system approximately 19 light-years away. The primary star is an orange dwarf star. 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.
Gliese 65, also known as Luyten 726-8, is a binary star system that is one of Earth's nearest neighbors, at 8.8 light-years from Earth in the constellation Cetus. The two component stars are both flare stars with the variable star designations BL Ceti and UV Ceti.
Gliese 1 is a red dwarf in the constellation Sculptor, which is found in the southern celestial hemisphere. It is one of the closest stars to the Sun, at a distance of 14.2 light years. Because of its proximity to the Earth it is a frequent object of study and much is known about its physical properties and composition. However, with an apparent magnitude of about 8.6 it is too faint to be seen with the naked eye.
Gliese 674(GJ 674) is a small red dwarf star with an exoplanetary companion in the southern constellation of Ara. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 9.38 and an absolute magnitude of 11.09. The system is located at a distance of 14.8 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −2.9 km/s. It is a candidate member of the 200 million year old Castor stream of co-moving stars.
Gliese 105 is a triple star system in the constellation of Cetus. It is located relatively near the Sun at a distance of 23.6 light-years. Despite this, even the brightest component is barely visible with the unaided eye (see Bortle scale). No planets have yet been detected around any of the stars in this system.
Gliese 687, or GJ 687 (Gliese–Jahreiß 687) is a red dwarf in the constellation Draco. This is one of the closest stars to the Sun and lies at a distance of 14.84 light-years. Even though it is close by, it has an apparent magnitude of about 9, so it can only be seen through a moderately sized telescope. Gliese 687 has a high proper motion, advancing 1.304 arcseconds per year across the sky. It has a net relative velocity of about 39 km/s. It is known to have a Neptune-mass planet. Old books and articles refer to it as Argelander Oeltzen 17415.
Gliese 673 is an orange dwarf star in the constellation Ophiuchus. It has a stellar classification of K7V. Main sequence stars with this spectra have a mass in the range of 60–70% of solar mass (M☉).
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.
Gliese 86 is a K-type main-sequence star approximately 35 light-years away in the constellation of Eridanus. It has been confirmed that a white dwarf orbits the primary star. In 1998 the European Southern Observatory announced that an extrasolar planet was orbiting the star.
Gliese 445 is an M-type main sequence star in the northern part of the constellation Camelopardalis.
Gliese 752 is a binary star system in the Aquila constellation. This system is relatively nearby, at a distance of 19.3 light-years.
Gliese 433 is a dim red dwarf star with multiple exoplanetary companions, located in the equatorial constellation of Hydra. The system is located at a distance of 29.6 light-years from the Sun based on parallax measurements, and it is receding with a radial velocity of +18 km/s. Based on its motion through space, this is an old disk star. It is too faint to be viewed with the naked eye, having an apparent visual magnitude of 9.81 and an absolute magnitude of 10.07.
Gliese 179 is a small red dwarf star with an exoplanetary companion in the equatorial constellation of Orion. It is much too faint to be visible to the naked eye with an apparent visual magnitude of 11.94. The system is located at a distance of 40.5 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of –9 km/s. It is a high proper motion star, traversing the celestial sphere at an angular rate of 0.370″·yr−1.
Stein 2051 is a nearby binary star system, containing a red dwarf and a degenerate star, located in constellation Camelopardalis at about 18 ly from Earth.
Gliese 809 is a red dwarf star in the constellation Cepheus, forming the primary component of a multi-star system. A visual magnitude of 8.55 makes it too faint to see with the naked eye. It is part of the Gliese Catalogue of Nearby Stars and is located about 23 light-years (ly) from the Solar System. Gliese 809 has about 70.5% the radius of the Sun and 61.4% of the Sun's mass. It has a metallicity of −0.06, which means that the abundance of elements other than hydrogen and helium is just 87.1% that of the Sun.
Gliese 180, is a small red dwarf star in the equatorial constellation of Eridanus. It is invisible to the naked eye with an apparent visual magnitude of 10.9. The star is located at a distance of 39 light years from the Sun based on parallax, and is drifting closer with a radial velocity of −14.6 km/s. It has a high proper motion, traversing the sky at the rate of 0.765 arcseconds per year.
GJ 3323 is a nearby single star located in the equatorial constellation Eridanus, about 0.4° to the northwest of the naked eye star Psi Eridani. It is invisible to the naked eye with an apparent visual magnitude 12.20. Parallax measurements give a distance estimate of 17.5 light-years from the Sun. It is drifting further away with a radial velocity of +42.3 km/s. Roughly 104,000 years ago, the star is believed to have come to within 7.34 ± 0.16 light-years of the Solar System.
Gliese 908 is a red dwarf star, located in constellation Pisces at 19.3 light-years from Earth. It is a BY Draconis variable star with a variable star designation of BR Piscium. Its apparent magnitude varies between magnitude 8.93 and magnitude 9.03 as a result of starspots and varying chromospheric activity.
Gliese 49 is a star in the northern constellation of Cassiopeia. Visually, it is located 106 arcminutes north of the bright star γ Cassiopeiae. With an apparent visual magnitude of 9.56, it is not observable with the naked eye. It is located, based on the reduction of parallax data of Gaia, 32.1 light-years away from the Solar System. The star is drifting closer to the Sun with a radial velocity of −6 km/s.