[81.05] Thermal and Non-Thermal Radio Continuum Emission from L1204

AAS 207th Meeting, 8-12 January 2006
Session 81 ISM: From Dark to Blinded
Poster, Tuesday, 9:20am-6:30pm, January 10, 2006, Exhibit Hall

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[81.05] Thermal and Non-Thermal Radio Continuum Emission from L1204

P. Machalek (JHU), R. J. Allen (STScI)

L1204 is a large dark dust cloud listed in Lynds catalogue with location l = 107.47^o, b = +4.81^o, and covering an area of 2.5 deg². The closely-associated object S140 is an extensively-studied HII region catalogued by Sharpless; it is much smaller, with an angular size of ~2' x 6', and is located about 0.9^o away on the southwestern edge of L1204. We have examined the 408 and 1420 MHz mosaic images of the region from the Canadian Galactic Plane Survey (CGPS). We found a large radio source of low surface brightness closely coinciding with the extended dust cloud L1204, along with many discrete sources (including S140) spread over the field. We present the distribution of radio spectral index over the cloud, as well as the spectral indices of many discrete sources. Preliminary results indicate that, whereas the radio continuum emission from S140 and several other discrete sources is thermal, the radio continuum emission from the extended source L1204 is non-thermal.

This research makes use of data from the Canadian Galactic Plane Survey.

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