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Mapping of large scale 158 mu m [CII] line emission: Orion A

Mookerjea, B and Ghosh, SK and Kaneda, H and Nakagawa, T and Ojha, DK and Rengarajan, TN and Shibai, H and Verma, RP (2003) Mapping of large scale 158 mu m [CII] line emission: Orion A. In: Astronomy & Astrophysics, 404 (2). pp. 569-578.

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Abstract

We present the first results of an observational programme undertaken to map the fine structure line emission of singly ionized carbon ([ CII] 157 : 7409 mum) over extended regions using a Fabry Perot spectrometer newly installed at the focal plane of a 100 cm balloon- borne far- infrared telescope. This new combination of instruments has a velocity resolution of similar to 200 km s(-1) and an angular resolution of 1.'5. During the first flight, an area of 30' x 15' in Orion A was mapped. These observations extend over a larger area than previous observations, the map is fully sampled and the spectral scanning method used enables reliable estimation of the continuum emission at frequencies adjacent to the [ CII] line. The total [ CII] line luminosity, calculated by considering up to 20% of the maximum line intensity is 0.04% of the luminosity of the far- infrared continuum. We have compared the [ CII] intensity distribution with the velocity- integrated intensity distributions of (CO)-C-13(1- 0), CI(1- 0) and CO( 3- 2) from the literature. Comparison of the [ CII], [ CI] and the radio continuum intensity distributions indicates that the largescale [ CII] emission originates mainly from the neutral gas, except at the position of M 43, where no [ CI] emission corresponding to the [ CII] emission is seen. Substantial part of the [ CII] emission from here originates from the ionized gas. The observed line intensities and ratios have been analyzed using the PDR models by Kaufman et al. ( 1999) to derive the incident UV flux and volume density at a few selected positions. The models reproduce the observations reasonably well at most positions excepting the [ CII] peak ( which coincides with the position of theta(1) Ori C). Possible reason for the failure could be the simplifying assumption of a homogeneous plane parallel slab in place of a more complicated geometry.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to EDP Sciences.
Keywords: infrared;ISM --ISM;lines and bands --ISM;individual(Orion A)
Department/Centre: Division of Physical & Mathematical Sciences > Joint Astronomy Programme
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 26 Aug 2011 10:39
Last Modified: 26 Aug 2011 10:39
URI: http://eprints.iisc.ernet.in/id/eprint/40135

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