2002/02/18 by F. Palla, D. Galli, Daniele Galli +4 · 1 citation
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Asymptotic giant branch #Hubble Deep Field #Hubble space telescope #Line (geometry) #Nebula #Nucleosynthesis #Physics #Planetary nebula #Space Telescope Imaging Spectrograph #Spectral line #Spectrograph #Spectroscopy #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/340270
12 pages, 3 figures, LaTeX. The Astrophysical Journal Letters, in press
arxiv created 2002/02/18 · openalex publication_date 2002/03/20 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
We present high-resolution Hubble Space Telescope ultraviolet spectroscopy of NGC 3242, the only planetary nebula with a measured abundance of 3 He. The Space Telescope Imaging Spectrograph has been used to observe the C III multiplet near 1908 Å. The presence of 12 C and 13 C lines at these wavelengths allows a direct estimate of the carbon isotopic ratio in the ionized gas of the nebula. We have detected the 12 C doublet and obtained an upper limit on the 13 C 1909.6 Å line, resulting in a carbon isotopic ratio of 12 C/ 13 C > 38, in agreement with standard stellar models. The lack of the 13 C line and the presence of the 3 He line in the spectrum indicate that the progenitor star did not undergo a phase of deep mixing during the last stages of its evolution. The significance of this result for studies of stellar nucleosynthesis and Galactic chemical evolution is discussed.