mass loss from galactic bulge agb stars€¦ · solar neigh. schulteis et al. 2003 . mass loss rate...
Post on 21-Jul-2020
3 Views
Preview:
TRANSCRIPT
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 • 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.)
ISOGal sample: spectroscopy of 107 candidate AGB stars
Schulteis et al. 2003
Metallicity of Bulge ISOGal sample
bulge
Solar neigh.
Schulteis et al. 2003
Mass Loss rate from IR
Schulteis et al. 2003
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…
Vexp Vexp V0
V0-Vexp
V0+Vexp
V0 Jy
V0 V0-Vexp V0+Vexp
Vexp
Vexp
Mass Loss rates from CO
Knapp & Morris (1985) Ramstedt et al. (2008)
Velocity integrated intensity CO abundance
Distance
Beam size
Prior work: CO detected in Galactic AGB stars/ OH-IR stars:
Winnberg et al. 2009
CO detected in Galactic AGB stars/ OH-IR stars: OH0.3-0.2
Winnberg et al. 2009
CO detected in Galactic AGB stars/ OH-IR stars: OH 359.762
Winnberg et al. 2009
Our SMA sample
Schulteis name log Mdot (IR) Type
Vstar (km/s)
Del-V (km/s)
A12 -4.65 OH 359.77+0.08 107.60 30A51 -4.73 OH 359.681-0.095 -98.70 20A10 -4.75 OH 359.598+0.00 -73.30 40A27 -4.78 AGB ? ?
Galactic Bulge: A12, OH 359.77+0.08
Galactic Bulge: A12, OH 359.77+0.08
Galactic Bulge: A51, OH 359.681-0.095
Galactic Bulge: A51, OH 359.681-0.095
Preliminary results from SMA sample
Schulteis name Comment
line flux (JyXkm/s) Mdot
A12 detected 42.5 8.3x10^-4A51 detected 32 6.24x10^-4A10 confused … ?A27 3 potential … ?
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
top related