Is Rotation a Really Important Property for the Understanding of the Evolution of Massive Stars?

ABSTRACT The presence of massive stars (MSs) in the region close to the Galactic Centre (GC) poses several questions about their origin. The harsh environment of the GC favours specific formation scenarios, each of which should imprint characteristic kinematic features on the MSs. We present a 2D kinematic analysis of MSs in a GC region surrounding Sgr A* based on high-precision proper motions obtained with the Hubble Space Telescope. Thanks to a careful data reduction, well-measured bright stars in our proper-motion catalogues have errors better than 0.5 mas yr−1. We discuss the absolute motion of the MSs in the field and their motion relative to Sgr A*, the Arches, and the Quintuplet. For the majority of the MSs, we rule out any distance further than 3–4 kpc from Sgr A* using only kinematic arguments. If their membership to the GC is confirmed, most of the isolated MSs are likely not associated with either the Arches or Quintuplet clusters or Sgr A*. Only a few MSs have proper motions, suggesting that they are likely members of the Arches cluster, in agreement with previous spectroscopic results. Line-of-sight radial velocities and distances are required to shed further light on the origin of most of these massive objects. We also present an analysis of other fast-moving objects in the GC region, finding no clear excess of high-velocity escaping stars. We make our astro-photometric catalogues publicly available.

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Interior Modelling of Massive Stars in Multiple Systems

10.1007/978-3-030-66310-0 ◽

2021 ◽

Author(s):

Cole Johnston

Keyword(s):

Massive Stars ◽

Multiple Systems

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The effects of different Type Ia SN yields on Milky Way chemical evolution

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab293 ◽

2021 ◽

Vol 503 (3) ◽

pp. 3216-3231

Author(s):

Marco Palla

Keyword(s):

Chemical Evolution ◽

White Dwarf ◽

Time Distribution ◽

Milky Way ◽

Massive Stars ◽

Abundance Patterns ◽

Type Ia ◽

Low Metallicity ◽

Explosion Mechanism ◽

Chemical Evolution Model

ABSTRACT We study the effect of different Type Ia SN nucleosynthesis prescriptions on the Milky Way chemical evolution. To this aim, we run detailed one-infall and two-infall chemical evolution models, adopting a large compilation of yield sets corresponding to different white dwarf progenitors (near-Chandrasekar and sub-Chandrasekar) taken from the literature. We adopt a fixed delay time distribution function for Type Ia SNe, in order to avoid degeneracies in the analysis of the different nucleosynthesis channels. We also combine yields for different Type Ia SN progenitors in order to test the contribution to chemical evolution of different Type Ia SN channels. The results of the models are compared with recent LTE and NLTE observational data. We find that ‘classical’ W7 and WDD2 models produce Fe masses and [α/Fe] abundance patterns similar to more recent and physical near-Chandrasekar and sub-Chandrasekar models. For Fe-peak elements, we find that the results strongly depend either on the white dwarf explosion mechanism (deflagration-to-detonation, pure deflagration, double detonation) or on the initial white dwarf conditions (central density, explosion pattern). The comparison of chemical evolution model results with observations suggests that a combination of near-Chandrasekar and sub-Chandrasekar yields is necessary to reproduce the data of V, Cr, Mn and Ni, with different fractions depending on the adopted massive stars stellar yields. This comparison also suggests that NLTE and singly ionized abundances should be definitely preferred when dealing with most of Fe-peak elements at low metallicity.

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Progenitors and Hydrodynamics of Type II and lb Supernovae

International Astronomical Union Colloquium ◽

10.1017/s0252921100008009 ◽

1996 ◽

Vol 145 ◽

pp. 137-147

Author(s):

S. E. Woosley ◽

T. A. Weaver ◽

R. G. Eastman

Keyword(s):

Black Holes ◽

Light Curve ◽

Mass Loss ◽

Massive Stars ◽

The Other ◽

Shock Interaction ◽

Type Ii ◽

Residual Hydrogen ◽

Ordinary Type ◽

The One

We review critical physics affecting the observational characteristics of those supernovae that occur in massive stars. Particular emphasis is given to 1) how mass loss, either to a binary companion or by a radiatively driven wind, affects the type and light curve of the supernova, and 2) the interaction of the outgoing supernova shock with regions of increasing pr3 in the stellar mantle. One conclusion is that Type II-L supernovae may occur in mass exchanging binaries very similar to the one that produced SN 1993J, but with slightly larger initial separations and residual hydrogen envelopes (∼1 Mʘ and radius ∼ several AU). The shock interaction, on the other hand, has important implications for the formation of black holes in explosions that are, near peak light, observationally indistinguishable from ordinary Type II-p and lb supernovae.

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Evolution Through Helium Burning — Massive Stars

Astronomy and Astrophysics Library - Stellar Structure and Evolution ◽

10.1007/978-3-642-61523-8_31 ◽

1990 ◽

pp. 292-307

Author(s):

Rudolf Kippenhahn ◽

Alfred Weigert

Keyword(s):

Massive Stars ◽

Helium Burning

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Radiation-Driven Stellar Eruptions

Galaxies ◽

10.3390/galaxies8010010 ◽

2020 ◽

Vol 8 (1) ◽

pp. 10 ◽

Cited By ~ 2

Author(s):

Kris Davidson

Keyword(s):

Mass Loss ◽

Radiation Pressure ◽

Central Region ◽

Massive Stars ◽

Variable Stars ◽

Blast Waves ◽

Subsequent Evolution ◽

Fundamental Causes ◽

Radiative Output ◽

Luminous Blue Variable

Very massive stars occasionally expel material in colossal eruptions, driven by continuum radiation pressure rather than blast waves. Some of them rival supernovae in total radiative output, and the mass loss is crucial for subsequent evolution. Some are supernova impostors, including SN precursor outbursts, while others are true SN events shrouded by material that was ejected earlier. Luminous Blue Variable stars (LBV’s) are traditionally cited in relation with giant eruptions, though this connection is not well established. After four decades of research, the fundamental causes of giant eruptions and LBV events remain elusive. This review outlines the basic relevant physics, with a brief summary of essential observational facts. Reasons are described for the spectrum and emergent radiation temperature of an opaque outflow. Proposed mechanisms are noted for instabilities in the star’s photosphere, in its iron opacity peak zones, and in its central region. Various remarks and conjectures are mentioned, some of them relatively unfamiliar in the published literature.

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