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Discovery of a New Supernova Remnant in the Direction of G69.7+1.0.pdf

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a r X i v : a s t r o - p h / 0 0 0 8 3 3 8 v 1 2 2 A u g 2 0 0 0 PASJ: Publ. Astron. Soc. Japan , –?? (2008) Discovery of a New Supernova Remnant in the Direction of G69.7+1.0 Kumi Yoshita, Emi Miyata, and Hiroshi Tsunemi Department of Earth and Space Science, Graduate School of Science, Osaka University 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 E-mail(KY): kyoshita@ess.sci.osaka-u.ac.jp (Received 1999 December 27; accepted 2000 April 20) Abstract We discovered a middle-aged supernova remnant in the vicinity of G69.7+1.0 using the ASCA satellite. G69.7+1.0 was identified in the 2.7 GHz survey and classified as a shell-type SNR with a diameter of 16′. During the ROSAT all-sky survey, the X-ray emission was detected in the direction of G69.7+1.0. However, it extends beyond the radio shell, and an X-ray bright region was located outside of the radio shell. A spectral study with the ASCA and ROSAT shows a thin thermal plasma with an electron temperature of ~ 0.4 keV. There is no significant variation of the spectral parameters over the field of view, except for the lower column density of the eastern part. We also found a large shell structure which surrounds the X-ray bright region in both optical and radio images. We suggest that the observed X-ray emission is associated with the large optical and radio shell, and that they are part of a new SNR, different from the radio SNR G69.7+1.0, which we have named AX J2001+3235 or G69.4+1.2. The large shell and the electron temperature of ~ 0.4 keV indicate that AX J2001+3235 is an evolved SNR. From a comparison with the column density of CTB 80 (G69.0+2.7), we estimate that the distance of the SNR is about 2.5 kpc. Key words: ISM: individual (G69.7+1.0) — supernova remnants — X-rays: ISM 1. Introduction Most galactic supernova remnants (SNRs) have been discovered and classified by observations in the radio band. Green’s present catalog (1998 September version; Green 1998) lists 220 SNRs. These remnants are clas- sifie
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