- Home
- Volume 93 - Année 2024
- No 2 - Proceeedings of the 3rd BINA Workshop on th...
- Measuring Hydrogen-to-Helium Ratio in Cool Stars
View(s): 442 (8 ULiège)
Download(s): 0 (0 ULiège)
Measuring Hydrogen-to-Helium Ratio in Cool Stars
Attached document(s)
original pdf fileAbstract
Conventionally, the helium-to-hydrogen ratio for the stars are adopted to be 0.1, as standard, unless, the stars are severely deficient in hydrogen like in RCB-class, or the stars’ helium abundance is accurately measured using He I transitions in warm/hotter stars. In our study, the small change in helium-to-hydrogen ratio (from standard value, 0.1) in normal giants were detected from the large difference (> 0.3 dex) in the Mg-abundance measured from Mg I lines and the subordinate lines of (0,0) MgH band. These are the stars that are mildly hydrogen-deficient/He-enhanced. Such stars were spectroscopically discovered for the first time among giants of the globular cluster ω Centauri. The sample selection, observations, methodoloy and results are discussed in detail.