The impact of an updated ¹⁴N(p, γ)¹⁵O reaction rate on advanced evolutionary stages of low-mass stellar models

¹ INAF - Osservatorio Astronomico di Teramo, via M. Maggini, 64100 Teramo, Italy
e-mail: pietrinferni@oa-teramo.inaf.it ; cassisi@oa-teramo.inaf.it
² Astrophysics Research Institute, Liverpool John Moores University, 12 Quays House, Birkenhead, CH41 1LD, UK
e-mail: ms@astro.livjm.ac.uk

Received: 28 May 2010
Accepted: 25 June 2010

Abstract

We investigate the impact of the ¹⁴N(p,γ)¹⁵O reaction rate as redetermined by the LUNA experiment, on the shell H-burning and core He-burning phases of low-mass, metal-poor stellar models. The new reaction rate has small but noticeable effects, the largest one being a  ~7−8% reduction in the red giant branch lifetimes. To different degrees, the lifetimes and luminosities of horizontal branch models, the mass of the stellar models evolving within the RR Lyrae instability strip, the luminosity of the red giant branch luminosity function bump, the theoretical calibrations of the R-parameter, and the tip of the red giant branch luminosity are also affected. Predictions for the tip of the red giant branch luminosity, in particular, are in very good agreement with the currently available empirical constraints.