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PRELIMINARY RESULTS FROM RTT150 OBSERVATIONS OF SUPERNOVA
REMNANTS IN TWO SPIRAL GALAXIES

AYSUN AKYUZ1, EDA SONBAS1, SOLEN BALMAN2, EYYUP CEKMECELIOGLU1 .EKMECEL.O.LU1

1.Cukurova University, Adana, Turkey
2.ODTU, Ankara

Supernova remnants (SNRs) are important probes of the interstellar medium.
Although the sample of Galactic remnants is large it is plagued by
interstellar extinction and uncertain distances. This problems are much
less in extragalactic samples. A number of nearby spiral galaxies have
already been observed in order to identify SNRs in them (D'Odorico, Dopita &
Benvetui 1980, Braun & Walterbos 1993, Magnier et al 1995, Matonick & Fesen
1997, Gordon et al. 1998). SNR surveys have been carried out at optical,
radio and X-ray wavelengths ( Pannuti et al. 2002 ). One of the objectives
of this work is to derive radial distribution of supernova remnant surface
densities in spiral galaxies. This project will help in extending the
database so that we can meaningfully explore the SNR distribution as a
function galaxy type. Other objectives include the comparison of the SNR
radial distribution with the radial distribution of HII regions to look
for any association between Type II progenitors and the SNRs and comparison
of the SNR distribution to the spiral arm patterns. We also plan future
follow-up spectroscopic observations for SNRs detected in these galaxies.

In this work, we present the results of an optical search for SNRs in the
spiral galaxies NGC3184 and NGC2903. The SNR identification technique
consisted of constructing continuum-subtracted H-alpha and [SII]
lambda lambda 6716, 6731 images and then using [SII] / H-alpha ratios
obtained from the image. The SNR candidates are normally identified as
nebulae that have raised [SII] / H-alpha >=0.4 compared with HII regions
0.1- 0.3. Our list of candidates contains 20 objects in NGC3184 and 6
objects in NGC2903. We compare our SNR candidate list against the existing
X-ray observations of the two galaxies. Knowing the positions of the SNRs,
we can compare their distributions relative to HII regions and spiral arms.
These observations were performed with the 1.5m Russian-Turkish Telescope
(RTT150) Spectrograph TFOSC's (TUG Faint Object Spectrograph and Camera)
CCD imaging system using narrowband interference filters at Turkish National
Observatory (TUG). Furthermore, it is aimed to have the extended SNR
catalogue with these two spiral galaxies and previously examined NGC6946
and NGC628 galaxies.

REFERENCES

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Matonick, D. M. et. al., ApJS. 112, 49M (1997)
Gordon et.al., ApJS, 117, p.89 (1998)
Pannuti T.G., ApJ, 565, 2, p. 966-981 (2002)