ALMA observes red giant star R Hare

The ground-based radio astronomical observatory ALMA has photographed the red giant star R Hare and its circumstellar envelope. This occurred when observing the sample at the highest angular resolution. This article was published in Astrophysical Journal. Low- and intermediate-mass stars, including our Sun, are in the final stage of their lives on an asymptotic giant branch, accompanied by mass loss and the formation of circumstellar shells. A variety of molecules and dust exist in abundance, and by tracking them we can understand the structure of the outer layers of stars and the mechanism of mass loss. A team of astronomers led by ALMA’s Yoshiharu Asagi will use ALMA test observations in 2021 to obtain the highest achievable angular resolution of 5 milliarcseconds (equivalent to a linear scale of 2.4 AU for this star). We announced the observation results of the star R Hare. . This was achieved through the use of a radio frequency receiver, an antenna array configuration with a maximum baseline length of 16 kilometers, and a new calibration technique that compensates for the effects of the Earth’s atmosphere on the observation data.

R Lepus is a red giant star located 1536 light-years from the Sun in the constellation Lepus, and is a Mira Cetus variable star with a pulsation period of 445 days. The resulting image shows submillimeter radiation from the star’s photosphere in orange, corresponding to a radius of 3 to 4 astronomical units. Shown in blue is the hydrogen cyanide maser emission, which forms a ring-like structure 10 to 60 AU in diameter, located in the innermost part of the circumstellar shell where stellar wind acceleration processes occur. This confirms the assumption that it comes from the area.