{"paper":{"title":"On a new parameter to estimate the helium content in old stellar systems","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.CO"],"primary_cat":"astro-ph.SR","authors_text":"A. Calamida, A. Di Cecco, A. Kunder, A. M. Piersimoni, A. Pietrinferni, A. R. Walker, A. Weiss, C. E. Corsi, F. Caputo, F. Troisi, G. Bono, G. Iannicola, I. Ferraro, L. Pulone, M. Dall'Ora, M. Fabrizio, M. Monelli, M. Nonino, M. Romaniello, M. Zoccali, P. B. Stetson, R. Buonanno","submitted_at":"2011-06-14T14:54:02Z","abstract_excerpt":"We introduce a new parameter {\\Delta}{\\xi} - the difference in magnitude between the red giant branch (RGB) bump and a point on the main sequence (MS) at the same color as the bump, the \"benchmark\" - to estimate the helium content in old stellar systems. Its sensitivity to helium is linear over the entire metallicity range, it is minimally affected by age, uncertainties in the photometric zero-point, reddening or the effects of evolution on the horizontal branch. The two main drawbacks are the need for precise and large photometric data sets, and a strong dependence of the {\\Delta}Y/{\\Delta}{\\"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1106.2734","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}