The trigger of the AGB superwind: the importance of carbon

Details The trigger of the AGB superwind: the importance of carbon The trigger of the AGB superwind: the importance of carbon

2008-07-23

arxiv.org/abs/0807.3730v1

Astronomy and Astrophysics

Astrophysics

accepted for publications in MNRAS Letters, 5 pages, 4 figures

Scientific paper

10.1111/j.1745-3933.2008.00535.x

The driving mechanism of the AGB superwind has become controversial in recent years. The efficacy of dust-driven mass loss has been queried. Spitzer observation of AGB stars in Local Group Galaxies show the surprising result that at low metallicity, AGB mass loss occurs at low luminosity, possibly lower than in the Galaxy, but only for carbon-rich stars. Oxygen-rich stars in the Galaxy and in lower metallicity galaxies have similar mass-loss rates only at high luminosities. To explain this dichotomy, we propose that the superwind has a dual trigger. The superwind starts either when sufficient excess carbon builds up for efficient formation of carbonaceous dust (which we propose occurs when $X_{\rm CO} = \rm (C - O)/ O_\odot = 0.1$), or when the luminosity reaches a value sufficient for a silicate-dust-driven wind (proposed at $L = 10^4 Z^{-4/3} \rm L_\odot)$. We show that this dual trigger fits the current observational constraints: the luminosity at which the superwind begins, and the predominance of carbon superwind star at low metallicity. We use stellar evolution models to check the consistency of our explanations and present detailed predictions of the luminosities at which the superwind is triggered for different metallicities and initial stellar masses.

Affiliated with

Also associated with

No associations

Rating

The trigger of the AGB superwind: the importance of carbon does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The trigger of the AGB superwind: the importance of carbon, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The trigger of the AGB superwind: the importance of carbon will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1466