NOAO >   Observing Info >   Approved Programs >   2016B-0155

Small NOAO Logo

Program Information for 2016B-0155


PI: Kenneth H Hinkle, NOAO, hinkle@noao.edu
Address: PO BOX 26732, TUCSON, AZ 85719 USA

CoI: Thomas Lebzelter, Universitat Wien (University of Vienna)
CoI: Oscar Straniero, INAF
CoI: Verne V Smith, NOAO

Title: Isotopes on a hot bottom: Nucleosyntheis in massive AGB stars

Abstract: Carbon and oxygen are key players in nucleosynthesis processes in the stellar interior. The isotopic ratios of these elements harbor important information on conditions deep inside the star. In stars of mass less than ~8 solar masses large scale mixing events during the late stages of stellar evolution bring this material to the surface. Surface carbon and oxygen isotopic ratios then reveal details of the evolution and mixing processes as well as the initial mass and initial abundances. Significantly for the chemical history of the universe this phase coincides with peak mass loss to the ISM. In this proposal we want to test the effect of hot bottom burning (HBB) on these key isotopes, i.e. the changes occurring in Asymptotic Giant Branch (AGB) stars of more than four solar masses. Stellar evolution models predict a strong decrease in 18O abundance. This would explain pre-solar grains showing low values. 17O is an initial mass indicator while the carbon isotopic ratio tells the story of the mixing processes. Our proposal aims at testing these predictions by obtaining high-resolution near-infrared spectra of a carefully selected sample of the most luminous AGB stars in the Large Magellanic Cloud.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2016B):  GEM-S-SVC/PHNX -- 20hrs band 2 (GS-2016B-Q-44)


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2016B-0155

noaoprop-help@noao.edu

Small NOAO Logo