HR 4523
Encyclopedia
HR 4523 is a binary star
system that is located in the northeastern part of the Centaurus
constellation
, at a distance of about 30.07 ly from the Solar System
. The larger member of the system is a G-type star that is smaller than the Sun
but of similar mass. It has a common proper motion
companion that was discovered by W. J. Luyten
in 1960. This M-type star appears to be in a wide orbit around the primary at a current separation of about 211 Astronomical Units (A.U.), (or 211 times the separation of the Earth from the Sun). By comparison, Neptune orbits at an average distance of 30 A.U.
The stellar classification
for the primary star in this system is G2V; the same as the Sun. That of the red dwarf
companion is M4V. The primary star has an estimated 86% to 89% the mass of the Sun
, 96% of the Sun's radius, and 85% of the Sun's luminosity. It is a slow rotator, with a projected rotational velocity
of 0.5 km/s. Age estimates range from 4.5–5.7 Gyr up to 7.1 Gyr or 9.48 Gyr. Compared to the Sun, it only has about 52% of the abundance of elements other than hydrogen and helium; what astronomers term the metallicity
of a star.
This star system has a relatively large proper motion. The HR 4523 system is a member of the Epsilon Indi
Moving Group, although it is most likely an interloper. (The star is older and has a different composition than the other group members.) It has space velocity
components = .
did not reveal an excess emission that would otherwise suggest the presence of a circumstellar debris disk
.
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
system that is located in the northeastern part of the Centaurus
Centaurus
Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.-Stars:...
constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
, at a distance of about 30.07 ly from the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
. The larger member of the system is a G-type star that is smaller than the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
but of similar mass. It has a common proper motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...
companion that was discovered by W. J. Luyten
Willem Jacob Luyten
Willem Jacob Luyten was a Dutch-American astronomer.-Life:Jacob Luyten was born in Semarang, Java, at the time part of the Dutch East Indies. His mother was Cornelia M. Francken and his father Jacob Luyten, a French teacher.At the age of 11 he observed Halley's comet, which started his...
in 1960. This M-type star appears to be in a wide orbit around the primary at a current separation of about 211 Astronomical Units (A.U.), (or 211 times the separation of the Earth from the Sun). By comparison, Neptune orbits at an average distance of 30 A.U.
The stellar classification
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
for the primary star in this system is G2V; the same as the Sun. That of the red dwarf
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
companion is M4V. The primary star has an estimated 86% to 89% the mass of the Sun
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
, 96% of the Sun's radius, and 85% of the Sun's luminosity. It is a slow rotator, with a projected rotational velocity
Stellar rotation
Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface....
of 0.5 km/s. Age estimates range from 4.5–5.7 Gyr up to 7.1 Gyr or 9.48 Gyr. Compared to the Sun, it only has about 52% of the abundance of elements other than hydrogen and helium; what astronomers term the metallicity
Metallicity
In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
of a star.
This star system has a relatively large proper motion. The HR 4523 system is a member of the Epsilon Indi
Epsilon Indi
Epsilon Indi is a K-type main-sequence star approximately 12 light-years away in the constellation of Indus. Two brown dwarfs, found in 2003, orbit the star.- Observation :...
Moving Group, although it is most likely an interloper. (The star is older and has a different composition than the other group members.) It has space velocity
Space velocity
Space velocity may be about,* Space velocity , the velocity of a star in the Galactic coordinate system.* Space velocity , the relation between volumetric flow and reactor volume in a chemical reactor....
components = .
Planetary system
The primary star is believed to be orbited by a Neptune-like planet with a mass 16 times that of the Earth. The orbital period of this planet is 122.1 days. No other planets have been discovered orbiting this star. An examination of this system in the infraredInfrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
did not reveal an excess emission that would otherwise suggest the presence of a circumstellar debris disk
Debris disk
A debris disk is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks have been found around both evolved and young stars, as well as at least one debris disk in orbit around a...
.