The Fastest Stars in the Galaxy: Unveiling their Origins and Probing Fundamental Physics

by Prof. Hagai Perez

Technion

at Physics Colloquium

Tue, 05 Nov 2024, 12:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015

Abstract

This colloquium will explore the origins and theoretical implications of the fastest known stars in the Milky Way, emphasizing their role as powerful tools for probing fundamental physics. When we speak of the "fastest stars", we refer to those objects exhibiting extreme velocities, far exceeding the typical motions of stars in the Galaxy. This includes two primary categories: hypervelocity stars, some of which are ejected from the Galactic center with speeds exceeding 1000 km/s, and the fast S-stars, orbiting the central massive black hole (MBH) at speeds approaching 10,000 km/s.

After a brief overview of the observational characteristics of these stellar speedsters, we will focus on the theoretical models explaining their extreme velocities. The tidal disruption of binary systems by the MBH, will be explored as a key driver for both the ejection of hypervelocity stars and the capture of S-stars orbiting the MBH. This mechanism provides a fascinating link between these two seemingly distinct populations. We will also discuss how the dynamics of stars near an MBH are critical to our understanding of the origins of these stars, and how these stars can probe fundamental physical questions about general relativity and the properties of black holes.

We will then delve into the intriguing case of hypervelocity white dwarfs. These objects offer unique insights into the physics of type Ia supernovae, which play a key role in producing the elements in the universe, and their progenitor systems. We will explore various progenitor models, including double-degenerate scenarios involving the merger of two white dwarfs, and their connection to the observed properties of hypervelocity white dwarfs. Furthermore, we will discuss how the study of these fast-moving white dwarfs can shed light on the origins of peculiar thermonuclear supernovae, such as sub-luminous events, which challenge our standard understanding of these explosions.

This colloquium aims to provide a comprehensive overview of the fastest stars in our Galaxy, focusing on the theoretical frameworks that explain their existence and highlighting their crucial role in our understanding of stellar dynamics, galactic evolution, and fundamental physics.

Created on 21-10-2024 by Maniv, Eran (eranmaniv)
Updaded on 31-10-2024 by Maniv, Eran (eranmaniv)