How Odd is Betelgeuse?
(2020) In Lund Observatory Examensarbeten ASTK02 20201Lund Observatory - Undergoing reorganization
- Abstract
- The role of massive stars (those with masses greater than eight solar masses) in the chemical enrichment of galaxies and renewed star formation forms an important field of fundamental research in modern astrophysics. The complex nature of massive star evolution produces formidable challenges in furthering our understanding of the processes driving massive star evolution. Our ever-changing picture is further complicated by the relatively recent realisation that the vast majority of massive stars are formed in multiple star systems. In close binaries, interactions between the stars can lead to an exchange of matter, dramatically altering the structure and evolution of the component stars and the binary system as a whole.
Depending on the... (More) - The role of massive stars (those with masses greater than eight solar masses) in the chemical enrichment of galaxies and renewed star formation forms an important field of fundamental research in modern astrophysics. The complex nature of massive star evolution produces formidable challenges in furthering our understanding of the processes driving massive star evolution. Our ever-changing picture is further complicated by the relatively recent realisation that the vast majority of massive stars are formed in multiple star systems. In close binaries, interactions between the stars can lead to an exchange of matter, dramatically altering the structure and evolution of the component stars and the binary system as a whole.
Depending on the initial binary configuration, this transfer of mass may be stable or unstable, producing results varying from wide binaries with massive secondaries, to common envelopes with tight binaries or even stellar mergers. A fraction of binary systems will be disrupted when the primary star explodes as a supernova, producing a runaway secondary star.
Alpha-Orionis, commonly known as Betelgeuse, is believed to be the product of such a scenario. We synthesise a realistic population of binary systems containing massive stars and simulate the evolution of these systems accounting for mass transfer through Roche lobe overflow. We analyse the probability for each system to be disrupted after the supernova explosion of the primary for a range of supernova kicks and determine which fraction of these systems will produce a secondary star in the estimated mass range of Betelgeuse. We also investigate which mass transfer channel is most likely to produce a Betelgeuse-like star.
We find that ~ 14% and ~ 25% of binaries will produce a secondary in the mass ranges 13-18 M_sun and 11-20 M_sun, respectively, allowing for the large uncertainties in determining the mass of Betelgeuse. Of these Betelgeuse candidates, approximately 75% emerge from systems following stable mass transfer.
We show the dependence of the fraction of bound systems on the magnitude and direction of the supernova kick velocity and the pre-supernova orbital elements of the binary. We establish the requirement for substantial supernova kicks in the disruption of close binaries and the generation of runaway velocities consistent with that of Betelgeuse. We also briefly
discuss mechanisms other than post-supernova ejections which lead to runaway massive stars and how these might apply to Betelgeuse-like stars. (Less) - Popular Abstract (Swedish)
- Mellan hösten 2019 och våren 2020, fängslades både professionella och amatöra astronomer
av de besynnerliga händelserna av Betelgeuse. Den särskiljande, lysande röda supergiant av
Orions axel, vanligtvis den tionde ljusaste stjärnan på himlen, började dämpa sig dramatiskt.
Detta fick många att spekulera om dess överhängande förstörelse i en kataklysmisk supernovaexplosion. Man tror nu att denna tillfälliga minskning av ljusstyrkan orsakades förmodligen av damm och gas från stjärnan som fördunklade vår vy, men till och med världens ledande astrofysiker är osäkra på de exakta fysiska processerna bakom sådana händelser. Man kan naturligtvis undra varför en väl studerad stjärna som Betelgeuse förblir ett mysterium.
Så kallade... (More) - Mellan hösten 2019 och våren 2020, fängslades både professionella och amatöra astronomer
av de besynnerliga händelserna av Betelgeuse. Den särskiljande, lysande röda supergiant av
Orions axel, vanligtvis den tionde ljusaste stjärnan på himlen, började dämpa sig dramatiskt.
Detta fick många att spekulera om dess överhängande förstörelse i en kataklysmisk supernovaexplosion. Man tror nu att denna tillfälliga minskning av ljusstyrkan orsakades förmodligen av damm och gas från stjärnan som fördunklade vår vy, men till och med världens ledande astrofysiker är osäkra på de exakta fysiska processerna bakom sådana händelser. Man kan naturligtvis undra varför en väl studerad stjärna som Betelgeuse förblir ett mysterium.
Så kallade dvärgstjärnor, som vår sol, lever länge. Det finns många av dem och är därför väl förstådda. Samma sak kan dock inte sägas om massiva stjärnor som Betelgeuse. De lever snabbt och dör unga, deras livslängd mäts i miljoner år istället för miljarder - bara ett ögonblick på kosmologiska tidsskalor. Att komplicera frågor ytterligare, studier tyder på att de flesta massiva stjärnor inte bildas isolerat; snarare är de födda i system som innehåller två
(eller fler) stjärnor. När dess stjärnor utvecklas och påverkar varandra, utbyter de material, som förändra deras struktur och ytterligare utveckling.
Ett möjligt resultat av dessa interaktioner i ett binärt system är utkastet av den mindre stjärnan efter att dess partner exploderar som en supernova. Betelgeuse verkar vara en ensam, flyktig stjärna, rusande genom rymden med stor hastighet, långt borta från födelseplatsen. Det är då mycket troligt att den var en gång del av ett binärt system som senare kastades ut av dess mer massiva partner.
I det här arbetet, simulerar vi en population av binära system som innehåller massiva stjärnor. Vi utforskar de olika typerna av interaktioner som dessa stjärnor genomgår med varandra medan de utvecklas. Efter den mer massiva stjärnan exploderar som en supernova, analyser vi vilken procentandel av systemen producerar en flyktig stjärna som liknar Betelgeuse och bestämmer vad vi kan säga, om något alls, om Betelgeuses evolutionshistoria. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9025185
- author
- Oshaughnessy, Martin LU
- supervisor
-
- Ross Church LU
- organization
- course
- ASTK02 20201
- year
- 2020
- type
- M2 - Bachelor Degree
- subject
- keywords
- Betelgeuse, runaway stars, stellar evolution, binary interactions
- publication/series
- Lund Observatory Examensarbeten
- report number
- 2020-EXA169
- language
- English
- id
- 9025185
- date added to LUP
- 2020-08-10 10:37:48
- date last changed
- 2020-08-10 10:37:48
@misc{9025185,
abstract = {{The role of massive stars (those with masses greater than eight solar masses) in the chemical enrichment of galaxies and renewed star formation forms an important field of fundamental research in modern astrophysics. The complex nature of massive star evolution produces formidable challenges in furthering our understanding of the processes driving massive star evolution. Our ever-changing picture is further complicated by the relatively recent realisation that the vast majority of massive stars are formed in multiple star systems. In close binaries, interactions between the stars can lead to an exchange of matter, dramatically altering the structure and evolution of the component stars and the binary system as a whole.
Depending on the initial binary configuration, this transfer of mass may be stable or unstable, producing results varying from wide binaries with massive secondaries, to common envelopes with tight binaries or even stellar mergers. A fraction of binary systems will be disrupted when the primary star explodes as a supernova, producing a runaway secondary star.
Alpha-Orionis, commonly known as Betelgeuse, is believed to be the product of such a scenario. We synthesise a realistic population of binary systems containing massive stars and simulate the evolution of these systems accounting for mass transfer through Roche lobe overflow. We analyse the probability for each system to be disrupted after the supernova explosion of the primary for a range of supernova kicks and determine which fraction of these systems will produce a secondary star in the estimated mass range of Betelgeuse. We also investigate which mass transfer channel is most likely to produce a Betelgeuse-like star.
We find that ~ 14% and ~ 25% of binaries will produce a secondary in the mass ranges 13-18 M_sun and 11-20 M_sun, respectively, allowing for the large uncertainties in determining the mass of Betelgeuse. Of these Betelgeuse candidates, approximately 75% emerge from systems following stable mass transfer.
We show the dependence of the fraction of bound systems on the magnitude and direction of the supernova kick velocity and the pre-supernova orbital elements of the binary. We establish the requirement for substantial supernova kicks in the disruption of close binaries and the generation of runaway velocities consistent with that of Betelgeuse. We also briefly
discuss mechanisms other than post-supernova ejections which lead to runaway massive stars and how these might apply to Betelgeuse-like stars.}},
author = {{Oshaughnessy, Martin}},
language = {{eng}},
note = {{Student Paper}},
series = {{Lund Observatory Examensarbeten}},
title = {{How Odd is Betelgeuse?}},
year = {{2020}},
}