Issue |
A&A
Volume 389, Number 3, July III 2002
|
|
---|---|---|
Page(s) | 855 - 870 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20020721 | |
Published online | 01 July 2002 |
6-m telescope spectroscopic observations of the bubble complex in NGC 6946
1
Sternberg Astronomical Institute of Moscow State University, Universitetsky Prospect, 13, Moscow, 119899, Russia
2
Special Astrophysical Observatory of RAS, Nizhnij Arkhyz, Karachai-Circassia, 369167, Russia
3
Isaac Newton Institute of Chile, SAO Branch, Russia
4
Max Planck Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany
5
IBM Research Division, T.J. Watson Research Center, PO Box 218, Yorktown Heights, NY 10598, USA
6
UC Observatories / Lick Observatory, University of California, Santa Cruz, CA 95064, USA
7
Instituto de Astrofisica de Andalucia, 18008 Granada, Spain
8
University of Washington, Seattle, USA
9
Grupo de Astronomía, Departamento de Física, Casilla 160-C, Universidad de Concepción, Concepción, Chile
Corresponding author: Yu. N. Efremov, efremov@sai.msu.ru
Received:
9
September
2001
Accepted:
16
May
2002
We describe the results of a long-slit spectroscopic study of an
unusual star complex in the nearby spiral galaxy NGC 6946 using
the SAO 6 m telescope and the Keck 10 m telescope. The complex
resembles a circular bubble 600 pc in diameter with a young super
star cluster (SSC) near the center. The kinematics of ionized gas
is studied through Hα emission with several slit positions.
Position–velocity diagrams show two distinct features with high
speed motions. One is an irregularly shaped region to the east of
the SSC, 270 pc in size, in which most of the Hα
emission is blue shifted by 120 km s-1, and another is a 350
pc shell centered on the SSC with positive and negative velocity
shifts of 60 km s-1. Balmer and absorption lines
in the SSC give an age of 12–13 Myr, which is consistent with
the photometric age but significantly older than the kinematic
ages of the high speed regions. The energetics of the SSC and its
interaction with the environment are considered. The expansion
energies exceed 1052 ergs, but the power outputs from winds
and supernova in the SSC are large enough to account for this. The
intensities of Balmer, [
], and [
] emission
lines within and around the complex indicate that shock excitation
makes a significant contribution to the emission from the most
energetic region.
Key words: galaxies: ISM / galaxies: globular clusters: general / galaxies: formation / galaxies: individual: NGC 6946 / ISM: bubbles
© ESO, 2002
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