Issue |
A&A
Volume 461, Number 3, January III 2007
|
|
---|---|---|
Page(s) | 991 - 997 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20054786 | |
Published online | 16 October 2006 |
The optical properties of the G89.0+4.7 (HB 21) supernova remnant
1
Technological Education Institute of Crete, General Department of Applied Scienses, PO Box 1939, 710 04 Heraklion, Crete, Greece e-mail: fotis@physics.uoc.gr
2
Institute of Astronomy & Astrophysics, National Observatory of Athens, I. Metaxa & V. Pavlou, P. Penteli, 152 36 Athens, Greece
Received:
29
December
2005
Accepted:
25
August
2006
Flux-calibrated CCD images of HB 21 are presented, along
with flux calibrated spectra of moderate resolution. The low ionization images
reveal filamentary structures in the east, while the emission in the central to
west areas may be either filamentary or patchy.
The filaments in the east are correlated very well with
the radio emission, but a smaller degree of correlation exists for the
patchy emission. An area in the west exhibits strong sulfur
emission and is probably associated to the remnant.
Uncatalogued regions are present in the area of the remnant,
mainly in the south.
We find that an ellipse extending for
incorporates most of the radio and optical emission.
The actual physical extent of the remnant depends on the distance, which
is not well determined since it ranges from 0.8 to 1.7 kpc.
Deep long-slit spectra were also acquired at a number of locations.
The Hα emission is generally weak, typically below 15
10-17 erg s-1 cm-2 arcsec-2. The
Hβ emission was not always detected, suggesting substantial attenuation
of the light through the interstellar medium. The medium ionization line of
[
]5007 Å was not detected indicating low shock velocities into the
interstellar clouds whose density is estimated to be a few atoms per cm3.
Key words: ISM: general / ISM: supernova remnants / ISM: individual objects: G 89.0+4.7
© ESO, 2007
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