Beta Arietis (β Arietis, abbreviated Beta Ari, β Ari), officially named Sheratan , is a star system and the second-brightest star in the constellation of Aries, marking the ram's second horn.

Nomenclature

''Beta Arietis'' is the star's Bayer designation. It also bears the

Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while co ...

''6 Arietis''. The traditional name, ''Sheratan'' (or ''Sharatan, Sheratim),'' in full ''Al Sharatan,'' is from the Arabic الشرطان ''aš-šaraţān'' "the two signs", a reference to the star having marked the northern vernal equinox together with

Gamma Arietis Gamma Arietis (γ Arietis, abbreviated Gamma Ari, γ Ari) is a binary star (possibly trinary) in the northern constellation of Aries. The two components are designated γ1 Arietis or Gamma Arietis B and γ2 Arietis or Gamma Arie ...

several thousand years ago. In 2016, the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name ''Sheratan'' for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names. In

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of ...

, (), meaning ''

Bond Bond or bonds may refer to: Common meanings * Bond (finance), a type of debt security * Bail bond, a commercial third-party guarantor of surety bonds in the United States * Chemical bond, the attraction of atoms, ions or molecules to form chemica ...

(asterism)'', refers to an asterism consisting of β Arietis, γ Arietis and α Arietis. Consequently, the

Chinese name Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are ofte ...

for β Arietis itself is (, en, the First Star of Bond).香港太空館 - 研究資源 - 亮星中英對照表
, Hong Kong Space Museum. Accessed on line November 23, 2010.

Properties

Beta Arietis has 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 2.66. Based on parallax measurements, it is located at a distance of from Earth. This is a spectroscopic binary star system consisting of a pair of stars orbiting around each other with a separation that can not currently be resolved with a conventional telescope. However, the pair have been resolved using the Mark III Stellar Interferometer at the

Mount Wilson Observatory The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observat ...

. This allows the orbital elements to be computed, as well as the individual masses of the two stars. The stars complete their highly

elliptical orbit In astrodynamics or celestial mechanics, an elliptic orbit or elliptical orbit is a Kepler orbit with an eccentricity of less than 1; this includes the special case of a circular orbit, with eccentricity equal to 0. In a stricter sense, i ...

every 107 days. The primary star has a stellar classification of A5 V, which means it is an

A-type main-sequence star An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between ...

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 in its core region. The NStars project gives the star a spectral type of kA4 hA5 mA5 Va under the revised

MK spectral 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 the ...

system. The

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

of the secondary star has not been determined, but, based on the mass, it may have a stellar classification of F5 III–V or G0 V. It is about four magnitudes fainter than the primary; hence the energy output from the system is dominated by the primary star. In a few million years, as the primary evolves toward a red giant, significant amounts of mass transfer to the secondary component is expected. The primary has been classified as a rapid rotator, 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 bulg ...

of 73 km/s providing a lower bound on the

azimuth An azimuth (; from ar, اَلسُّمُوت, as-sumūt, the directions) is an angular measurement in a spherical coordinate system. More specifically, it is the horizontal angle from a cardinal direction, most commonly north. Mathematical ...

al rotational velocity along the equator. It may also be a mildly

Am star An Am star or metallic-line star is a type of chemically peculiar star of spectral type A whose spectrum has strong and often variable absorption lines of metals such as zinc, strontium, zirconium, and barium, and deficiencies of others, such as ca ...

, which is a class of stars that show a peculiar spectrum with strong

absorption lines A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identi ...

from various elements and deficiencies in others. In β Arietis, these absorption lines are broadened because of the Doppler effect from the rotation, making analysis of the abundance patterns difficult. This system has been examined with the Spitzer Space Telescope for the presence of an excess emission of infrared, which would indicate a disk of dust. However, no significant excess was detected.

References

External links

GJ 80
Catalog
Image Beta Arietis

by Professor Jim Kaler.

{{DEFAULTSORT:Beta Arietis Aries (constellation) A-type main-sequence stars G-type main-sequence stars Spectroscopic binaries Sheratan Arietis, Beta Arietis, 06 011636 008903 0553 0080 Durchmusterung objects