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Mass Loss from Galactic Bulge AGB stars

Mass Loss from Galactic Bulge AGB stars. Margaret Meixner (STScI/ visiting Scientist at Harvard-Smithsonian CfA) Nimesh Patel, Dave Riebel, Ben Sargent, Sundar Srinivasan, Ken Young. Why Galactic Bulge?. Known Distance: 8 kpc (Reid 1993) Extreme environment

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Mass Loss from Galactic Bulge AGB stars

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  1. Mass Loss from Galactic Bulge AGB stars Margaret Meixner (STScI/ visiting Scientist at Harvard-Smithsonian CfA) Nimesh Patel, Dave Riebel, Ben Sargent, Sundar Srinivasan, Ken Young

  2. Why Galactic Bulge? • Known Distance: 8 kpc (Reid 1993) • Extreme environment • High metallicity: peak at -0.3, but wide range: -1<[Fe/H]<1 • ISOGal studies reveal a population of AGB star candidates suitable for followup (Omont et al.) • Prior studies show that all AGB stars in bulge are oxygen rich, with silicate dust features (Blommaert et al.)

  3. ISOGal sample: spectroscopy of 107 candidate AGB stars Schulteis et al. 2003

  4. Metallicity of Bulge ISOGal sample bulge Solar neigh. Schulteis et al. 2003

  5. Mass Loss rate from IR Schulteis et al. 2003

  6. SMA project: • Use SMA to spatially filter the foreground CO cloud emission, and detect the point source AGB molecular winds of Galactic Bulge AGB stars. • Use extended SMA configuration, and observe two AGB stars per track. • Goal: to measure gas mass-loss rates, compare to dust mass-loss rates and estimate dust to gas mass ratios • Data taken last week…

  7. Vexp V0 Vexp Vexp Vexp V0-Vexp V0 Jy V0+Vexp V0+Vexp V0-Vexp V0

  8. Mass Loss rates from CO Beam size CO abundance Distance Velocity integrated intensity Knapp & Morris (1985) Ramstedt et al. (2008)

  9. Prior work: CO detected in Galactic AGB stars/ OH-IR stars: Winnberg et al. 2009

  10. CO detected in Galactic AGB stars/ OH-IR stars: OH0.3-0.2 Winnberg et al. 2009

  11. CO detected in Galactic AGB stars/ OH-IR stars: OH 359.762 Winnberg et al. 2009

  12. Our SMA sample

  13. Galactic Bulge: A12, OH 359.77+0.08

  14. Galactic Bulge: A12, OH 359.77+0.08

  15. Galactic Bulge: A51, OH 359.681-0.095

  16. Galactic Bulge: A51, OH 359.681-0.095

  17. Preliminary results from SMA sample

  18. Future Prospects • Continue this galactic bulge project to collect larger numbers and statistics • This project demonstrates an approach that could be used for LMC and SMC AGB samples, but with ALMA

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