oMEGACat V: Helium Enrichment in $\omega$ Centauri as a Function of Metallicity

Autor(en)

C. Clontz, A. C. Seth, Z. Wang, S. O. Souza, M. Häberle, M. S. Nitschai, N. Neumayer, M. Latour, A. P. Milone, A. Feldmeier-Krause, N. Kacharov, M. Libralato, A. Bellini, G. van de Ven, M. Alfaro-Cuello

Abstrakt

Constraining the helium enhancement in stars is critical for understanding the formation mechanisms of multiple populations in star clusters. However, measuring helium variations for many stars within a cluster remains observationally challenging. We use Hubble Space Telescope photometry combined with MUSE spectroscopic data for over 7,200 red-giant branch stars in \omc\ to measure helium differences between distinct groups of stars as a function of metallicity separating the impact of helium enhancements from other abundance variations on the pseudo-color (chromosome) diagrams. Our results show that stars at all metallicities have subpopulations with significant helium enhancement ($\Delta Y_{min} \gtrsim$ 0.11). We find a rapid increase in helium enhancement from low metallicities ($\rm{[Fe/H] \simeq -2.05}$ to $\rm{[Fe/H] \simeq -1.92})$, with this enhancement leveling out at \deltay\ $= 0.154$ at higher metallicities. The fraction of helium-enhanced stars steadily increases with metallicity ranging from 10\% at $\rm{[Fe/H] \simeq -2.04}$ to over $90\%$ at $\rm{[Fe/H] \simeq -1.04}$. This study is the first to examine helium enhancement across the full range of metallicities in \omc{}, providing new insight into its formation history and additional constraints on enrichment mechanisms.

Organisation(en)

Institut für Astrophysik

Journal

The Astrophysical Journal

ISSN

0004-637X

DOI

https://doi.org/10.48550/arXiv.2412.09783

Publikationsdatum

12-2024

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/e63c8f57-1fa3-47fa-bd07-133e4aa1aae3