Modelling Long-Period Variables -- II. Fundamental mode pulsation in the nonlinear regime

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 periods. Here, we use a 1D hydrodynamic code to investigate the long-period variability of M-type asymptotic giant branch stars in the nonlinear 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, nonlinear models predict an earlier onset of dominant fundamental mode 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 analytic relations describing the nonlinear fundamental mode 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 nonlinear pulsation, and probe possible effects of varying metallicity and carbon abundance.

18 pages, 17 figures; accepted for publication in MNRAS

References in corpus (16)

• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• Constraining the thermally-pulsing asymptotic giant branch phase with resolved stellar populations in the Small Magellanic Cloud
• Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud
• The pulsation modes, masses and evolution of luminous red giants
• Non-radial oscillations in M-giant semi-regular variables: Stellar models and Kepler observations
• A new interpretation of the period-luminosity sequences of long-period variables
• Dynamical Opacity-Sampling Models of Mira Variables. I: Modelling Description and Analysis of Approximations
• Tracing the development of dust around evolved stars: The case of 47 Tuc
• Carbon-Rich Mira Variables: Kinematics and Absolute Magnitudes
• Large Magellanic Cloud Near-Infrared Synoptic Survey. V. Period-Luminosity Relations of Miras
• Asteroseismology of luminous red giants with Kepler I: Long Period Variables with radial and non-radial modes
• An Infrared Census Of Dust In Nearby Galaxies With Spitzer (DUSTiNGS): V. The Period-luminosity Relation For Dusty Metal-Poor AGB Stars
• The onset of the AGB wind tied to a transition between sequences in the period-luminosity diagram
• The M33 Synoptic Stellar Survey. II. Mira Variables
• Strange pulsation modes in luminous red giants
• Long Secondary Periods in luminous red giant variables

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