Download DUST FROM EVOLVED STARS TO PROTOSTARS. A. K. Speck

Disks, Meteorites, Planetesimals Workshop (2010)
DUST FROM EVOLVED STARS TO PROTOSTARS.
A. K. Speck, University of Missouri ([email protected])
Introduction: Dust is a vital ingredient in understanding
many astrophysical processes [e.g. 1, 2, 3]. It is an essential part
of star formation processes; it is the key to understanding mass
loss from aging stars [e.g. 4]; and it contributes to several aspects
of interstellar processes such as gas heating and the formation of
molecules [e.g. 5]. Furthermore, dust has been observed at higher
redshifts than expected, and understanding this phenomenon is
vital to our understanding of the cosmos at large and its evolution
[e.g. 6, 7].Such a crucial and ubiquitous constituent of our Universe needs to be well understood in its own right, if we are to
understand its contributions to many aspects of astrophysics.
Evolved Stars: Intermediate-mass stars (0.8-8.0 solar
masses) are major contributors of new elements to interstellar
space [8]. These stars eventually evolve into asymptotic giant
branch (AGB) stars. During the AGB phase, these stars suffer
intensive mass loss leading to the formation of circumstellar
shells of dust and neutral gas, including the new elements formed
during the star’s life [9]. Using a combination of observing techniques (e.g. infrared (IR) spectroscopy, visible, IR and sub-mm
imaging) and laboratory IR studies, combined with theoretical
considerations (e.g. kinetics and thermodynamics of the dustforming region; nucleosynthesis models and changing stellar
chemistries) and meteoritic evidence.
Combining astrophysics and meteoritics: Understanding
the interplay between observational and theoretical astrophysics
and meteoritic studies of presolar grains is crucial to furthering
studies of dust in space. This is especially true for dust around
evolved intermediate mass stars, where the majority of meteoritic
presolar grains originate. New laboratory data combined with reanalysis of observational data for AGB stars will be presented.
Combined, these data present a challenge to the “common wisdom” on what we think we know about dust species in space.
References: [1] Videen, G., Kocifaj,, M., eds., 2002, Optics of
Cosmic Dust (NATO SCIENCE SERIES: II: Mathematics, Physics and Chemistry, vol. 79), Springer, pp 320. [2] Draine, B. T.,
2003, Astrophysical Journal, 598, 1017. [3] Krishna Swamy, K.
S., 2005, Dust in the Universe: Similarities and Differences,
World Scientific Publishing Co., p. 264. [4] Woitke, P., 2006,
Astronomy & Astrophysics, 460, L9. [5] Krugel, E., 2008, An
Introduction to the Physics of Interstellar Dust, Taylor & Francis,
p. 387. [6] Sloan et al., 2009, Science, 323, 353. [7] Bussmann et
al., 2009, Astrophysical Journal, 705, 184. [8] Kwok, S. 2004,
Nature, 430, 985. [9] Iben, I. Jr., Renzini, A. 1983, Annual Reviews of Astronomy & Astrophysics, 21, 271.
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