English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In a Globular Cluster (GC), the mass loss during the red-giant branch (RGB)phase and the helium content are fundamental ingredients to constrain thehorizontal branch (HB) morphology. While many papers have been dedicated to thehelium abundance in the different stellar populations, small efforts have beendone to disentangle the effects of mass loss and helium content. We exploit thenearby GC NGC6121 (M4), which hosts two well-studied main stellar populations,to infer both helium and RGB mass loss. We combine multi-band Hubble SpaceTelescope photometry of RGB and main sequence (MS) stars of M4 with syntheticspectra to constrain the relative helium content of its stellar populations. Wefind that the second generation stars in M4 is enhanced in helium mass fractionby $\rm \Delta Y = 0.013 \pm 0.002$ with respect to the remaining stars thathave pristine helium content. We then infer the mass of the HB stars bysearching for the best match between the observations and HB populationsmodelled assuming the helium abundance of each population estimated from theMS. By comparing the masses of stars along the HB, we constrain the mass lossof first- and second-generation stars in M4. We find that the mass lost by thehelium enriched population is $\sim 13$% larger than the mass lost by the firstgeneration stars ($\rm \Delta \mu = 0.027 \pm 0.006 \ M_\odot$). We discuss thepossibility that this mass loss difference depends on helium abundance, thedifferent formation environment of the two generations, or a combination ofboth.

Mass loss of different stellar populations in Globular Clusters: the case of M4