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Is there a metallicity ceiling to form carbon stars? - A novel technique reveals a scarcity of C stars in the inner M31 disk

Boyer, M. L. and Girardi, L. and Marigo, P. and Williams, B. F. and Aringer, B. and Nowotny, W. and Rosenfield, P. and Dorman, C. E. and Guhathakurta, P. and Dalcanton, J. J. and Melbourne, J. L. and Olsen, K. A. G. and Weisz, D. R. (2013) Is there a metallicity ceiling to form carbon stars? - A novel technique reveals a scarcity of C stars in the inner M31 disk. Astrophysical Journal, 774 (1). Art. No. 83. ISSN 0004-637X.

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We use medium-band near-infrared (NIR) Hubble Space Telescope WFC3 photometry with model NIR spectra of asymptotic giant branch (AGB) stars to develop a new tool for efficiently distinguishing carbon-rich (C-type) AGB stars from oxygen-rich (M-type) AGB stars in galaxies at the edge of and outside the Local Group. We present the results of a test of this method on a region of the inner disk of M31, where we find a surprising lack of C stars, contrary to the findings of previous C star searches in other regions of M31. We find only one candidate C star (plus up to six additional, less certain C star candidates), resulting in an extremely low ratio of C to M stars (C/M = (3.3^(+20)_(-0.1)) x 10^(-4)) that is one to two orders of magnitude lower than other C/M estimates in M31. The low C/M ratio is likely due to the high metallicity in this region which impedes stars from achieving C/O > 1 in their atmospheres. These observations provide stringent constraints to evolutionary models of metal-rich AGB stars and suggest that there is a metallicity threshold above which M stars are unable to make the transition to C stars, dramatically affecting AGB mass loss and dust production and, consequently, the observed global properties of metal-rich galaxies.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Boyer, M. L.0000-0003-4850-9589
Williams, B. F.0000-0002-7502-0597
Guhathakurta, P.0000-0001-8867-4234
Olsen, K. A. G.0000-0002-7134-8296
Weisz, D. R.0000-0002-6442-6030
Additional Information:© 2013 American Astronomical Society. Received 2013 May 23; accepted 2013 July 12; published 2013 August 19. We thank the referee, Jacco van Loon, for thoughtful comments that improved the manuscript and helped to clarify important issues. This work was supported by the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by ORAU through a contract with NASA and by NASA through HST grant numbers GO-12862 and GO-12055 from the STScI, which is operated by AURA, Inc., under NASA contract NAS5-26555. P.M. and L.G. acknowledge support from Progetto di Ateneo 2012, University of Padova, ID: CPDA125588/12. This research was funded in part by the Austrian Science Fund (FWF): P21988-N16. Facility: HST (WFC3)
Funding AgencyGrant Number
NASA Postdoctoral Program at the Goddard Space Flight CenterUNSPECIFIED
HST grantGO-12862
Space Telescope Science InstituteGO-12055
Progetto di Ateneo 2012, University of PadovaCPDA125588/12
Austrian Science Fund (FWF)P21988-N16
Subject Keywords:galaxies: individual (M31); stars: AGB and post-AGB; stars: carbon; stars: late-type
Issue or Number:1
Record Number:CaltechAUTHORS:20130924-144126378
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Official Citation:Is There a Metallicity Ceiling to Form Carbon Stars?—A Novel Technique Reveals a Scarcity of C stars in the Inner M31 Disk M. L. Boyer et al. 2013 ApJ 774 83
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41513
Deposited By: Ruth Sustaita
Deposited On:24 Sep 2013 22:25
Last Modified:09 Mar 2020 13:19

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