Mu Gemini

μ Geminorum ( Latinized version of Mu Geminorum) is Bayer's designation .

Mu Gemini wore the traditional name Teyat / Teyat (Tejat) or Teyat / Teyat Posterior (Tejat Posterior), which means "back leg", because it is the foot of Castor , one of the Dioscuri twins . The name Teyat Posterior was previously applied to asterism , consisting of this star, along with Alhena , Nu Gemini , Pass and Xi Gemini, and probably that is why Bayer designated it with the letter “ μ ” (Mu) ^[13] . In 2016, the International Astronomical Union organized a Working Group under the IAU on Star Names (WGSN) ^[14] to catalog and standardize the proper names of stars. WGSN decided to assign proper names to individual stars, rather than to whole sets of star systems ^[15] . The group approved the name Tejat (Teyat, Teyat) for the WDS component J06230 + 2231A (i.e. Mu Twins) and since February 1, 2017 , and the star is included in the IAU Approved Star Name List ^[10] .

The names Calx (from the Latin word for “heel”), Pish Pai (from the Persian پیشپای (“pīshpāy”, meaning “foreleg”) and Nuhatai (from the Arabic “Al Nuḥātai”, the double form “Al Nuḥāt”, “camel's hump ") Were also applied to Mu Gemini ^[16] .

In Chinese astronomy, the star entered the constellation 井 宿 ( Jǐng Su )), which means " Tail ”, Consisting of Mu Twins, Twins Gamma, Twins Nu, Twins Xy, Twins Epsilon, Twins 36, Twins Geta , and Twins Lambda ^[17] . Therefore, Mu Gemini herself is known as 井 宿 一 ( Jǐng Su yī (Jǐng Su yī, “the first star of the tail”) ^[18] .

Having an apparent magnitude of 2.9 ^{m [2]} , Mu Twins is the fourth brightest star in the constellation (after Pollux , Castor and Alhena ). Since the star is located near the ecliptic , it is quite often covered by the moon ^[19] . When observed from the Earth, its brightness decreases by 0.07 ^m due to the absorption of light by gas and dust ^[4] .

The star is a slow irregular variable of type LB. Its brightness varies between +2.75 ^m and +3.02 ^m for a 72-day period, and it also has a 2,000-day period of long-term brightness variation.

The star itself is a red giant spectral class M3 III ^[6] , with a surface temperature of 3,773 K ^[20] , which means that it is brighter, but colder than the Sun ^{[3] [13]} . Teyat is a giant that emits 1,148 times more energy than the Sun (after correcting for the fact that most of it is emitted in infrared light ). Although not so large compared to some of the stars visible to the naked eye , however, the low temperature leads to the fact that the star becomes very large and close enough to be able to accurately measure its angular size , which is equal to it 0.0135 arc seconds . Teyat has a radius 80 times larger than that of the Sun , or 0.48 a. that is, approximately half the size of the Earth's orbit ^[13] .

The star, at present, is located on the asymptotic branch of the giants and generates the nuclear fusion energy of hydrogen and helium in its concentric shells surrounding the inert core of carbon and oxygen ^[21] .

The temperature and brightness of Teyat speak of a star more than twice as massive as the Sun. The star itself began its life as a hot dwarf of spectral class B, which now not only ended the hydrogen burning in its core, but also ended the burning of helium . Now, having a dead carbon core, the arrival evolves towards a much higher luminosity . Soon the star will flare up like the World , and, ultimately, will shed its outer shell to become a massive white dwarf like Sirius B ^[13] ..

Teyat is also marked as a star with high velocity in space. It moves about five times faster than normal speed relative to the Sun ^[13] .

WDS J06230 + 2231 - designation of a double star in the Washington catalog of visual binary stars . The designations of binary star components as WDS J06230 + 2231A and WDS J06230 + 2231BC are based on the convention used in the Washington Catalog of Multiple Star Systems (WMC) for Star Systems and adopted by the International Astronomical Union (MAS) ^[22] . Teyat has two probable companions, information about which is given in WDS ^[12] . The numbers after the discoverer code indicate the number of a specific entry in their catalogs ^[12] .

Information about the discoverer ^[12] .

The “companion”, the tenth magnitude (a double star itself), most likely lies on the same line of sight and the companion is most likely not a ^[13] .