Modelling long-period variables - II. Fundamental mode pulsation in the non-linear regime
- Author(s)
- Michele Trabucchi, Peter R. Wood, Nami Mowlavi, Giada Pastorelli, Paola Marigo, Léo Girardi, Thomas Lebzelter
- Abstract
Long-period variability in luminous red giants has several promising applications, all of which require models able to accurately predict pulsation periods. Linear pulsation models have proven successful in reproducing the observed periods of overtone modes in evolved red giants, but they fail to accurately predict their fundamental mode (FM) periods. Here, we use a 1D hydrodynamic code to investigate the long-period variability of M-type asymptotic giant branch stars in the non-linear regime. We examine the period and stability of low-order radial pulsation modes as a function of mass and radius, and find overtone mode periods in complete agreement with predictions from linear pulsation models. In contrast, non-linear models predict an earlier onset of dominant FM pulsation, and shorter periods at large radii. Both features lead to a substantially better agreement with observations that we verify against OGLE and Gaia data for the Magellanic Clouds. We provide simple analytical relations describing the non-linear FM period-mass-radius relation. Differences with respect to linear predictions originate from the readjustment of the envelope structure induced by large-amplitude pulsation. We investigate the impact of turbulent viscosity on linear and non-linear pulsation, and probe possible effects of varying metallicity and carbon abundance.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- Université de Genève, University of Padova, Australian National University, Osservatorio Astronomico
- Journal
- Monthly Notices of the Royal Astronomical Society
- Volume
- 500
- Pages
- 1575-1591
- No. of pages
- 17
- ISSN
- 0035-8711
- DOI
- https://doi.org/10.1093/mnras/staa3356
- Publication date
- 10-2021
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy, 103004 Astrophysics
- Keywords
- ASJC Scopus subject areas
- Astronomy and Astrophysics, Space and Planetary Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/c7ab43bd-9f63-4788-bc65-52ca8765e41f