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OU Symposium Slide Notes

General Format

  • 5 minute overview/background of our science
  • 5 minutes on our specific research
  • 5 minutes on our general computation need
  • 5 minutes on our specific analysis in relation to computation and what is our specific needs for computers
  • 5 minutes for results and greater impacts
  • 5 minutes for questions

Table of Contents

  • title slide: First Look at Protostars: High Fidelity Modeling and the Youngest of Stars with OSCER
  • collaboration: VANDAM, HOPS, misc
  • motivation
    • questions we try to answer are generally: where did we come from, what else is out there, and where are we going to end up?
    • questions we (specifically) answer: Where did we come from, how did we get here, what else is out there, and are we unique

(not everyone is an astronomer much less expert of star/planet formation)

  • background on star formation
    • evolution of stars: MC -> Protostar -> Main Sequence (star) -> Giants -> WD/NS/BH -> MC ...
      • What determines the specific track: to first order mass
      • whats interesting is once you hit MS, the only thing that matters (to first order) is mass
      • what determines MS and single/multiple star.
      • what about planets? Gas is gone so gas giant formation not possible at MS
    • Look at Cloud -> Class III
      • evolution
      • when does gas leave?
    • pictures of orion/perseus HST
    • these are optically thick....big problem
      • interesting, opacity is related to frequency so just go to longer wavelengths: IR/RADIO
  • Instruments
    • problem, resolution is also frequency dependent theta = lambda/size
      • so now we need large telescopes. We want <10AU scales and stuff is away so we need 0.1'' resolution
      • similar to saying 1/1000 of your fingernail width at arms length away from your eye.
      • which means we need telescopes on order of the size of km at least...
      • not doable
    • interferometry
      • lots of smaller telescopes across several miles acts like 1 big telescope(with limitations)
    • fixed our problems
      • alma, vla, noema, carma
    • so what kind of data do we get?
      • photometry
        • just like a camera from your cellphone we can get an image
        • if we do this a lot we get the energy distribution of objet
      • spectroscopy
        • this gives us color, not just 3 color but thousands. Gives us information of atoms, molecules
      • we get both simultaneously
    • so to summarize we went from HST -> ALMA
      • now we can look at the systems themselves and not just the environment or nulk properties
      • from these we can get stellar mass, disk mass, size, speeds, molecular abundance, temperatures, geometries, multiplicities, etc
  • Computation
    • parameters
      • we now have 20-40 parameters to fit with a lot of degeneracy
      • turning into a computation problem
      • we want to make a model, fit this model to the data, and then get the model parameters
      • sounds like a great problem for parallelization and MCMC
    • so now our problem is one of scalability
      • we want to reach numerical convergence of the models and statistical convergence of the model parameter sets
      • insert EMCEE,openmpi, pdspy
      • insert slide about scalability
    • computation requirements
      • generally models take 60k core-hours for a single system
        • we have a few hundred of these
      • our systems
        • 2x 28 physical core
        • so while good not enough (months of convergence)
      • into oscer
        • generally we ask for 5-15 nodes x 20 core x 48 hours x 15-5 separate runs x systems
        • some take more and some take less depending on complexity, how quickly they converge, etc
      • currently not GPU ready so we just want max CPU core hours
    • we are requesting a lot but why again?
  • impacts and fundamentals
    • we are trying to understand our universse and namely understand how did we form and what other things form in the universe
    • are we unique?
    • where/when/how do planets form and same for stars.
    • how do we get the tichness of chemicals
    • we want to answer these in a statistically significant way too so that means large observational surveys, lots of models
    • our group at OU + collaborations around the world are the forerunners of this field
  • thanks
    • none of this would happen without OSCER, OU, NSF, and the collaborators
    • special thanks to Henry, Horst, Oscer IT, and CAS IT