χ Eridani (Latinised as Chi Eridani) is a
binary star
A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in ...
[ system in the constellation Eridanus. It is visible to the naked eye with an ]apparent visual magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...
of 3.70.[ The distance to this system, as determined using the parallax method, is around 58 ]light year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s.[ The pair had an ]angular separation
Angular distance \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer.
Angular distance appears in mathematics (in pa ...
of 5.0 arcsecond
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
s as of 1994. This corresponds to a projected separation
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outsid ...
of around 128 AU.[
The primary component is an evolving ]G-type
Gaea
Gaea is one of the Elder Gods of Earth.
Gaia
Gaia, also known as the Guardian of the Universal Amalgamator, is a fictional superhero, depicted as possibly being a mutant or extraterrestrial. Created by Larry Hama, she first appeared in ...
subgiant
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...
star with a stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...
of G8 IV.[ It is about 1.6 times the mass of the Sun and has 4 times the Sun's radius.][ The star shines with 10 times the ]solar luminosity
The solar luminosity (), is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun.
One nomin ...
from its outer atmosphere at an effective temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...
of 5,115 K.[ Unusually for a star of this class, it shows a photometric variability of 0.04 in magnitude, which may be due to a previous mass transfer from the secondary companion, or else from an undiscovered third companion.][
The companion is about 7 magnitudes fainter than the primary and may be the source of the X
-ray emission from this system. This emission has a luminosity of .][
]
References
{{DEFAULTSORT:Chi Eridani
G-type subgiants
Binary stars
Eridanus (constellation)
Eridani, Chi
Durchmusterung objects
0081
011937
009007
0566