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Utrecht University

Student project: angular-momentum loss in stable, non-conservative mass transfer

Background

Some observed binary stars cannot be explained by stable, conservative mass transfer (SCMT) and/or a Common Envelope (CE). Clear examples are the double white dwarfs (DWDs) from this related project. It looks like the solution may be found in stable but non-conservative mass transfer (SNCMT). In addition, our project on the formation of LIGO-Virgo sources suggests that we can explain the observed sources better if we assume similar non-conservative mass transfer. A solution was proposed Nelemans et al. (2000) in the form of a "gamma prescription", based on angular-momentum balance, which can "explain" these systems. An issue is the sensitive dependence on gamma, explaining why reconstruction works well but implying that forward calculations lead to a wide range of outcomes for small variations in gamma. Secondly, there is little physics behind the model. However, I think it may be possible that the gamma prescription and SNCMT are the same thing.

Research questions

  • Can we describe the gamma prescription in terms of stable, non-conservative mass transfer?
  • Is stable, non-conservative mass transfer an explanation for the gamma prescription?
  • How closely do (or do not) resemble these two prescriptions each other? In which parts of the binary parameter space (M1, M2, Porb do we get better/worse matches?

Methods

This project is half theoretical, where you will derive a relation between SNCMT and gamma (if any), but also involves some computer analysis to compare your findings to existing and new population-synthesis models of binary populations, to create graphs, etc. The first half involves pen and paper, in the second half you need to be able to use Python. Your products are your thesis (+ LaTeX source and figures) and the Python code you developed.

Relevant background

Interested?

If you are interested in this project, please send me an email. If I'm on holiday (e.g. the beginning of January or September), send me a WhatsApp on my mobile to expedite things. (There will be plenty of arranging and reading for you to do until I get back, see Getting started.) You can find my email address and phone number on my home page.


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1 Section numbers may vary, as this is a living document.