CE meeting notes

Notes on EAS CE conference held July 2-3, 2020

  • Morgan MacLeod's ​CE bibliography. He says you can email him to suggest more relevant papers.
  • Worth checking out Paul Ricker's talk for his implementation of flux-limited radiative transfer: [recording ​https://portalapp.kuonicongress.eventsair.com/VirtualAttendeePortal/eas-annual-meeting-2020/virtual-eas/] but I'm unable to view it, possibly because I was a speaker during that session? Anyway, my notes say that his radiative transfer algorithm triggers on temperature gradient. He uses OPAL opacities. He says that a challenge of their simulations is that energy is trapped closer to the star than what may be realistic.
  • During my talk there was a question by Friedrich Roepke about AM conservation. We should measure it for the next paper.
  • Christian Sand's talk on CE with AGB star: gets 7.4 to 9.4 years ejection if recombination energy is included. Does not get enough unbinding with ideal gas EOS but not clear whether extra unbinding is caused by recombination or the difference in the initial profile between ideal gas EoS case and the OPAL EoS case (I think they use OPAL rather than the full MESA EoS). They think it's the recombination rather than the initial profile that makes the difference but have not done a test to confirm this. Both Paul Ricker and I were wondering about this.
  • David Jones: mass transfer could happen before, during or after CE phase. Since main sequence companions are almost always observed to be inflated (by up to 3 times), sometimes mass transfer may get reinitiated at the end of the CE phase (speculative). But worth thinking about. Would RLOF occur at the end of the simulation if the companion gets puffed up? Or would the secondary get tidally shredded?
  • Wouter Vlemmings: water fountain sources with high Mdot ~ 0.01 to 0.1 Msun/yr outflows, M_torus ~ 0.2-1.3 Msun. Estimate initial mass of system is ~ 1.4-2.4 Msun, so we are talking about low mass stars. I think it might be possible to explore these systems with CE simulations.
  • M. Santander-Garcia: Their hypothesis was that post-CE PNe should be more massive compared to non-post-CE PNe. They find confirmation of this at what he feels is a somewhat marginal level (~0.24 Msun for post-CE and ~0.17 Msun for regular sample). What he says is that a more interesting result is obtained when the post-CE sample is separated into single degenerate and double degenerate. DD have larger mass ~0.63 Msun compared to SD ~0.15 Msun. Something to think about.
  • In the discussion following Amy's talk Noam was arguing that there is not enough momentum in the regular AGB winds to explain the high momenta outflows observed in PPNe, so basically he was questioning the assumption of the model (echoed by another participant, Alcolea). He says therefore one needs a jet. Also appeals to the precession seen in some sources to argue for jets. Says that jets have been seen in post-AGB objects (refers to Van Winckel). Interestingly, Noam thinks that jets can emerge/break out before or after the CE phase, but are unable to do so during the CE phase.
  • In the discussion it was also mentioned by Paul Ricker (echoed by Morgan MacLeod) that in the Heidelburg group sims that utilize recombination energy, they compute that the energy is used in regions where tau>1, but maybe the radiative diffusion time is still small enough that the energy escapes to the surface, so maybe it could not be used so easily. They didn't seem to have an answer for that.
  • In the discussion, David Jones commented that post-CE PN CSs seem to be tidally locked, at least there is no evidence for asynchronous rotation. Again, perhaps something to think about.
  • In the discussion, David Jones also mentioned that mass is still missing in PNe. It is not all contained in the equatorial disk, so where is the rest? Alocolea says velocity profile does not fit story that equatorial material is left over CE ejecta, and he sees the velocity turning around (I guess this would imply fallback).
  • J. Jencson: SPRITES: rapid dust formation and dust obscures optical counterpart. I think this is another reason to have dust in our CE simulations.
  • N. Blogorodnova: From her talk I wonder if the secondary peak/plateau in LRNe/ILOTs caused by a second unbinding phase+merger. This does not seem to be the popular idea people have. They found for M31LRN 2015 that temperature increases with time at late times and that the luminosity agrees with gravitational contraction at fixed temperature. Anyway, her talk is mainly about observations of that source, and may be worth watching.

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