HD 37124 is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

in the

equatorial Equatorial may refer to something related to: *Earth's equator **the tropics, the Earth's equatorial region **tropical climate *the Celestial equator ** equatorial orbit **equatorial coordinate system ** equatorial mount, of telescopes * equatorial ...

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 ...

Taurus Taurus is Latin for 'bull' and may refer to: * Taurus (astrology), the astrological sign * Taurus (constellation), one of the constellations of the zodiac * Taurus (mythology), one of two Greek mythological characters named Taurus * ''Bos taurus ...

(the Bull), positioned about a half degree to the SSW of the bright star

Zeta Tauri Zeta Tauri (ζ Tauri, abbreviated Zeta Tau, ζ Tau) is a binary star in the zodiac constellation of Taurus, the Bull. It has an apparent visual magnitude of about 3.0, which is bright enough to be seen with the naked eye. Parallax measure ...

. The apparent visual magnitude of this star is 7.68, which is too dim to be visible to the naked eye. It is located at a distance of 103

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 from the Sun based on

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

, but is drifting closer with a

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

of −23 km/s. Three extrasolar planets have been found to orbit the star. The

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 HD 37124 is G4IV-V, showing a spectrum with blended traits of 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 Her ...

star and a more

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...

subgiant star. It is a quiet star with a low activity index. This star is smaller than the Sun, with 81–92% of the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

and around 92% of the Sun's radius. It is an older, thick disk star with an age of around 11 billion years, and is spinning with a

projected rotational velocity 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. The rotation of a star produces an equatorial bulge ...

of 3.6 km/s. The

metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

of the star, what astronomers term the abundance of heavier elements, is much lower than in the Sun with an iron abundance of 35–41%. It is radiating 77–84% of the Sun's luminosity from its

photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...

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 5,763 K.

Planetary system

As of 2011, three extrasolar planets have been found to orbit the star. Announced on the first of November 1999, the first planet (

HD 37124 b HD 37124 b is an extrasolar planet approximately 103 light-years away in the constellation of Taurus (the Bull). The planet was discovered in 1999 orbiting the star HD 37124. Based on its mass, it is most likely that this planet is a Jovian plan ...

) was discovered orbiting its parent star around the inner edge of the habitable zone, causing the planet to have a somewhat similar

insolation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...

to that of

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...

. A second planet became apparent by 2003, thought to orbit in a 1940 days on an eccentric orbit, but this was subsequently found to be unstable. Solving this, a three-planet solution was announced in 2005: this contained a second planet ( HD 37124 c) orbiting at the outer edge of the habitable zone with an insolation similar to that of

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

, and a third planet, ( HD 37124 d). While not obviously in any orbital resonances in 2005, an updated solution announced in 2011 found planets 'c' and 'd' to likely be in a 2:1 resonance.

References

External links

* * __NOTOC__ {{DEFAULTSORT:HD 37124 G-type main-sequence stars G-type subgiants Planetary systems with three confirmed planets Taurus (constellation) Durchmusterung objects 0209 037124 026381

Planetary system

See also

References

External links