Beta Reticuli (Beta Ret, β Reticuli, β Ret) is
binary star
A binary star or binary star system 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 as separate stars us ...
[ system in southern constellation of ]Reticulum
Reticulum is a small, faint constellation in the southern sky. Its name is Latin for a small net, or reticle—a net of crosshairs at the focus of a telescope eyepiece that is used to measure star positions. The constellation is best viewed b ...
. It is visible to the naked eye with an apparent visual magnitude of +3.84.[ Based upon an annual parallax shift of 33.49 mas,][ it is located some 97 ]light year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...
s from our Sun
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...
.
This is a single-lined spectroscopic binary with an orbital period
The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...
of 5.25 years and an eccentricity
Eccentricity or eccentric may refer to:
* Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal"
Mathematics, science and technology Mathematics
* Off-Centre (geometry), center, in geometry
* Eccentricity (g ...
of 0.33. The primary, component A, is an evolved
Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
K-type giant star
A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsp ...
with a stellar classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...
of K0 IVSB:. It is between 5 and 6 billion years old, with 1.2 times the mass of the Sun and 9.3 times the Sun's radius. The companion, component B, is most likely a red dwarf
A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...
with a classification in the range M0–M4.[
During the mid-20th century, the Dutch-American astronomer Willem Jacob Luyten proposed that the G3V star HD 24293 formed a third component of this system, based upon similar ]proper motion
Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...
s. However, this was subsequently ruled out based on more accurate measurements, since their actual distances, radial velocities, and proper motions do not match.[Beta Reticuli (HIP 17440)]
Beta Reticuli came closest to the Sun 319,000 years ago when it had brightened to magnitude 2.98 from a distance of 67 light years.[
]
Naming
In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, (), meaning '' Snake's Head'', refers to an asterism consisting of β Reticuli and α Hydri. Consequently, β Reticuli itself is known as (, .)AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 27 日
References
{{DEFAULTSORT:Beta Reticuli
K-type giants
M-type main-sequence stars
Spectroscopic binaries
Reticuli, Beta
Reticulum
023817
017440
1175
Durchmusterung objects