Luyten's Star (GJ 273) is a
red dwarf
''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...
in the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
Canis Minor
Canis Minor is a small constellation in the northern celestial hemisphere. In the second century, it was included as an asterism, or pattern, of two stars in Ptolemy's 48 constellations, and it is counted among the 88 modern constellation ...
located at a distance of approximately from the Sun. It has a
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 ...
of 9.9, making it too faint to be viewed with the unaided eye. It is named after
Willem Jacob Luyten
Willem Jacob Luyten (March 7, 1899 – November 21, 1994) was a Dutch-American astronomer.
"Willem Jacob Luyten", ''Marquis Who's Who'', 2006.
Life
Jacob Luyten was born in Semarang, Java, at the time part of the Dutch East Indies. His ...
, who, in collaboration with Edwin G. Ebbighausen, first determined its high
proper motion
Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
in 1935.
[ The star has two confirmed planets and two candidate planets,]circumstellar habitable zone
In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kas ...
.
Properties
This star is approximately a quarter the mass of the Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
[ Luyten's Star is at the maximum mass at which a red dwarf can be fully convective, which means that most if not all of the star forms an extended ]convection zone
A convection zone, convective zone or convective region of a star is a layer which is unstable due to convection. Energy is primarily or partially transported by convection in such a region. In a radiation zone, energy is transported by radiation ...
.[ It has 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 grati ...
of M3.5V,luminosity class
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 the ...
indicating this is a main-sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hert ...
star that is generating energy through the thermonuclear fusion
Thermonuclear fusion is the process of atomic nuclei combining or “fusing” using high temperatures to drive them close enough together for this to become possible. There are two forms of thermonuclear fusion: ''uncontrolled'', in which the re ...
of hydrogen at its core. The projected rotation rate of this star is too low to be measured, but can be no greater than 1 km/s.[ Measurements of periodic variation in surface activity suggest a leisurely rotation period of roughly 116 days (which would give a velocity of ~0.15 km/s).][ The ]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 the star's outer envelope is a relatively cool 3,150 K, giving the star the characteristic red-orange hue of an M-type star
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 the ...
.[
At present, Luyten's Star is moving away from the ]Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
. The closest approach occurred about 13,000 years ago when it came within 3.67 parsecs.Procyon
Procyon () is the brightest star in the constellation of Canis Minor and usually the eighth-brightest star in the night sky, with an apparent visual magnitude of 0.34. It has the Bayer designation α Canis Minoris, which is Latinize ...
, which would appear as a visual magnitude −4.5 star in the night sky of Luyten's Star's planets.[ However, Luyten's Star would only have an apparent magnitude of 4.6 from Procyon's sky because it is much less luminous. The closest encounter between the two stars occurred about 600 years ago when Luyten's Star was at its minimal distance of about 1.12 ly from ]Procyon
Procyon () is the brightest star in the constellation of Canis Minor and usually the eighth-brightest star in the night sky, with an apparent visual magnitude of 0.34. It has the Bayer designation α Canis Minoris, which is Latinize ...
.[
] The space velocity components of Luyten's Star are U = +16, V = −66 and W = −17 km/s.[
]
Planetary system
In March 2017, two candidate planets were discovered orbiting Luyten's Star.super-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively.
The term "super-Earth" refers only to ...
in its star's optimistic habitable zone. It has a minimum mass
In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes.
Minimum mass is a widely cited statistic for extrasolar planets detected by the radial veloc ...
of and orbits at a distance of completing one orbital period in While the planet is on the innermost edge of the star's conservative habitable zone, the incident flux is only 1.06 , so it may be potentially habitable if water and an atmosphere are present; depending on albedo, its equilibrium temperature
The planetary equilibrium temperature is a theoretical temperature that a planet would be if it were a black body being heated only by its parent star. In this model, the presence or absence of an atmosphere (and therefore any greenhouse effect) is ...
could be anywhere between 206 and 293 Kelvin. The inner planet, GJ 273c, is one of the lightest exoplanets detected by radial velocities, with a mass of only However, it orbits much further in, with an orbital period of only [
In October 2017, " Sónar Calling GJ273b", a project by METI and the Sónar music festival,][ The signal consisted of a scientific and mathematical tutorial on how to decode the messages and was accompanied by 33 encoded musical compositions by various musicians. A second signal series was transmitted in May 2018. Were anyone listening, the soonest response would be received by 2042.
]
See also
* List of nearest stars and brown dwarfs
This list covers all known stars, brown dwarfs, and sub-brown dwarfs within of the Sun. So far, 131 such objects have been found, of which only 22 are bright enough to be visible without a telescope. The visible light needs to reach or exce ...
Notes
References
External links
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{{DEFAULTSORT:Luyten's Star
Local Bubble
M-type main-sequence stars
Canis Minor
036208
0273
BD+05 1668
Planetary systems with four confirmed planets