Conveners
Rotation in Stellar Evolution: Block 1
- Georges Meynet (Geneva University)
Description
Rotation has become in the last decades a central topic in stellar physics. This is due to many reasons, the main ones being the fact that rotation can trigger many instabilities in stellar interiors driving transport of chemical species and angular momentum, deeply impacting the evolution of stars, their final fate and the nature and properties of their remnants (white dwarfs, neutron stars or black holes). At present, hello- and asteroseismology provide direct views on how our Sun, but also low-mass stars as subgiants and red giants rotate internally offering thus very strong constraints on these transport processes. This session will discuss the most recent constraints coming from asteroseismology, the confrontation of diverse models aiming to account for them, and the consequences of these theories for the spin of the stellar remnants.
In this talk I will briefly review the knowledge on angular momentum transport acquired from helio- and asteroseismology of low mass stars. I will discuss how rotation is determined from the seismic data, what results it has brought us for the Sun first, than other stars thanks to the space-based photometry missions. I will present the current shortcomings of the models, the various solutions...
The β Cephei pulsating stars are unique targets to probe our knowledge of the interior of massive stars. By analysing their pulsations with asteroseismology, we can explore the mixing processes, e.g., convection and overshooting, in the core of these massive stars. Asteroseismology has delivered another success by revealing their internal rotation. I illustrate these results with a review of...
We will discuss the initial rotation rates of massive stars, and the change of the rotation rates in single and binary
stars during their evolution, in connection to Be stars, accretion-induced spin-up and stellar mergers. We will then
consider the evolution of the core rotation of massive stars, and the corresponding expectations for the spins of compact
objects. In the end, we with...
The first stars in the Universe, the so-called Population III (Pop III), formed at the end of the cosmic dark ages, a few million years after the Big Bang. Their impact on early cosmic history, in terms of ionizing radiation and the initial enrichment of the intergalactic medium with heavy chemical elements, crucially depends on the Pop III initial mass function (IMF). Numerical simulations...
Supermassive stars (SMSs), with masses $>10^5$ M$_\odot$, have been proposed as the possible progenitors of the most extreme supermassive black holes observed at redshifts $z>6-7$. In this scenario ('direct collapse'), a SMS accrete at rates $>0.1$ M$_\odot$ yr$^{-1}$ until it collapses to a black hole via the general-relativistic (GR) instability. Rotation plays a crucial role in the...
Core-collapse supernova form a diverse class of explosions produced at the end of the lives of massive stars. We study numerically the process of formation of the compact remnants (proto-magnetars and black holes) resulting from the collapse of very compact, low-metallicity cores of high-mass stars. We aim at understanding the dependence of the stellar remnants properties on the stellar...
All ten LIGO/Virgo binary black hole (BH-BH) coalescences reported from the O1/O2 runs have near zero effective spins. The similar trend seems to be seen also in O3 results, alas with some exceptions. Even the famous massive event (GW190521: 85+66 Msun BH-BH merger) is fully consistent with having zero effective spin. I will discuss possible astrophysical implications of this intriguing...
The cores of (sub)giants rotate much slower than expected from known hydrodynamic braking mechanisms. Magnetic torques generated by differential rotation are potentially much more effective. I'll briefly review magnetorotational and Tayler instabilities, which in their current versions are also insufficient. A big problem facing improvement are a number of critical surprises encountered in...
