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Modeling Rapidly Fading Supernovae as Nickel-Free Core-Collapse Explosions of Extended Helium Stars


Kleiser, Io K. (2019) Modeling Rapidly Fading Supernovae as Nickel-Free Core-Collapse Explosions of Extended Helium Stars. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/5YEJ-EX71.


Supernovae are the engines of the universe, pulling material out of the furnaces of stars and spewing it out into their galaxies. As some of the most powerful explosions since the Big Bang, they influence not only the chemical but also mechanical evolution of the galaxies they inhabit. They induce star formation and produce the building blocks of planets, organisms, and ultimately, civilizations. Understanding the connections between the supernovae we observe and the stars that would have produced them is a critical piece of understanding this process.

Unfortunately, we rarely have the ability to observe the progenitor stars of supernovae directly; it is usually difficult to predict when a given star will explode, and most are in galaxies too distant to allow observation of individual stars. Instead, we typically must leverage our understanding of the explosions themselves to reveal the nature of the stars that produced them. Using analytical and numerical calculations, it is possible to predict the supernovae from certain types of stars and work backwards.

In this thesis, we present a new model for previously elusive rapidly fading supernovae, which we believe are due to the core-collapse explosions of massive stars inside extended hydrogen-free envelopes or previously ejected mass shells. This model requires not only pre-explosion stellar radii of unprecedented size for hydrogen-free stars but also a lack of radioactive nickel, which is usually present in supernovae. We show our process from simple toy models to self-consistent explosions of stellar models and compare our results to existing rapidly fading supernovae. Understanding these unusual transients will shed light on the many possible ways stars behave shortly before death and also may be critical for understanding the population of core-collapse supernovae as a whole.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Stars, supernovae
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Astrophysics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Phinney, E. Sterl (advisor)
  • Kasen, Daniel (co-advisor)
Group:Astronomy Department
Thesis Committee:
  • Hopkins, Philip F. (chair)
  • Steidel, Charles C.
  • Kulkarni, Shrinivas R.
  • Kirby, Evan N.
  • Phinney, E. Sterl
  • Kasen, Daniel
Defense Date:20 April 2018
Non-Caltech Author Email:io.k.w.kleiser (AT)
Funding AgencyGrant Number
National Nuclear Security AdministrationKrell Institute Fellowship Award
Record Number:CaltechTHESIS:09032018-174351545
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Ch. 6 adapted for Ch. 5 adapted for Ch. 4
Kleiser, Io K.0000-0001-5332-1156
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11170
Deposited By: Io Kleiser
Deposited On:27 Nov 2018 19:29
Last Modified:04 Oct 2019 00:23

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PDF (Thesis) - Final Version
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