From: Amara Graps (Amara.Graps@mpi-hd.mpg.de)
Date: Fri May 10 2002 - 08:57:05 MDT
(mirror)
http://xxx.uni-augsburg.de/abs/astro-ph/0205128
Astrophysics, abstract
astro-ph/0205128
From: Thomas W. Berghoefer <st8h305@hs.uni-hamburg.de>
Date: Wed, 8 May 2002 21:47:33 GMT (181kb)
The origin of the young stellar population in the solar neighborhood - a
link to the formation of the Local Bubble?
Authors: T. W. Berghoefer, D. Breitschwerdt
Comments: 8 pages, 2 figures, accepted for publication in A&A
We have analyzed the trajectories of moving stellar groups in the
solar neighborhood in an attempt to estimate the number of
supernova explosions in our local environment during the past 20
million years. Using Hipparcos stellar distances and the results
of kinematical analyses by Asiain et al. (1999a) on the Pleiades
moving groups, we are able to show that subgroup B1, consisting of
early type B stars up to 10 Msun, but lacking more massive
objects, has passed through the local interstellar medium within
less than 100 pc. Comparing the stellar content of B1 with the
initial mass function derived from the analysis of galactic OB
associations, we estimate the number of supernova explosions and
find that about 20 supernovae must have occurred during the past ~
10 - 20 million years, which is suggested to be the age of the
Local Bubble; the age of the star cluster is about ~ 20 - 30
million years. For the first time, this provides strong evidence
that the Local Bubble must have been created and shaped by
multi-supernova explosions and presumably been reheated more than
1 million years ago, consistent with recent findings of an excess
of 60Fe in a deep ocean ferromanganese crust. Calculating
similarity solutions of an expanding superbubble for
time-dependent energy input, we show that the number of explosions
is sufficient to explain the size of the Local Bubble. The present
energy input rate is about $\dot E_{SN}$ ~ 5 x 10^36 erg/s, in
good agreement with the estimated local soft X-ray photon output
rate. It seems plausible that the origin of the Local Bubble is
also linked to the formation of the Gould Belt, which originated
about 30-60 Myrs ago.
Paper: Source (181kb), PostScript, or Other formats
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Amara Graps, PhD | Max-Planck-Institut fuer Kernphysik
Heidelberg Cosmic Dust Group | Saupfercheckweg 1
+49-6221-516-543 | 69117 Heidelberg, GERMANY
Amara.Graps@mpi-hd.mpg.de * http://www.mpi-hd.mpg.de/dustgroup/~graps
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