Young lithium-rich giant star discovered
Young lithium-rich giant star discovered
December 4, 2015 by Tomasz Nowakowski
(Phys.org)—An Argentinian team of astronomers from the Astronomical Observatory of Córdoba has announced the finding of a new exceptional young lithium-rich giant star, designated KIC 9821622. Using the data obtained with the high-resolution GRACES spectrograph at the Gemini North telescope in Hawaii, the scientists were able to determine the chemical abundances of 23 elements of this star as well as reveal its mass, radius, and age. The results appear in the December issue of the Astronomy & Astrophysics journal.
According to the findings, KIC 9821622 is a lithium-abundant, intermediate-mass giant star (about 1.64 solar masses) located at the red giant branch near the luminosity bump, approximately 5,300 light years from Earth. Such lithium-rich stars are very rare; it is estimated that only 1 to 2 percent of all observed giants have at least the same amount of this element as KIC 9821622.
The star was observed as one of the first science targets taken for an on-sky test of the GRACES (Gemini Remote Access to CFHT ESPaDOnS Spectrograph). The observations were conducted in July 2015.
Aside from being lithium-rich, the scientists found that KIC 9821622 shows also a high abundance of carbon, nitrogen and oxygen. They also managed to derive the star's precise spectroscopic fundamental parameters, including the effective temperature, surface gravity, metallicity and microturbulent velocity.
Stars destroy most of their lithium soon after formation, consuming it at nuclear fusion temperatures. This element is not normally remade. Thus, what baffles scientists is how giant stars become rich in lithium.
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http://phys.org/news/2015-12-young-lithium-rich-giant-star.html#jCp