Discovery of a Cold Extended Condensation in the Orion A Complex
I. Ristorcelli, G. Serra, J. M. Lamarre, M. Giard, F. Pajot, J. P. Bernard, J. P. Torre, A. De Luca, J. L. Puget;
ApJ, 1998, 496, 267
ABSTRACT:The central region of the Orion A cloud complex has been observed in the submillimeter range, using the French balloon-borne 2 m telescope PRONAOS-SPM
during its first flight, in 1994 September.
An area covering 50' x 10' and
including the M42 Nebula has been mapped in four submillimeter photometric
bands: lambda 180-240, 240-340, 340-560, and 560-1050 mu m, with high
sensitivity (<=2 MJy sr-1) and an angular resolution from 2' to 3.'5.
Four
brightness enhancements are visible and have been identified with the following
sources: (1) the brightest peak corresponding to the central core of the nebula,
in the BN/KL source direction; (2) an extended emission region around 5' x
8', to the southeast of BN/KL, correlated with 100 mu m IRAS and 13CO
emission (this has been identified as a gas-density enhancement associated
with a shock region); (3) the edge of an ionized part of the cloud, correlated
with the 100 mu m emission; and (4) a very cold and extended condensation,
discovered at 16' northwest of BN/KL.
The emission spectra obtained for these
sources show a variation of the dust emissivity spectral index within a large
range, from 1 +/- 0.1 to 2.2 +/- 0.2.
The cold condensation discovered (T = 12.5
+/- 3 K) has a very low brightness emission, undetected on the 100 mu m IRAS
map.
It extends over approximately 0.7 pc (FWHM), with a total mass of 11 M&sun;
and a total luminosity of 2.4 L&sun;.
KEYWORDS: balloons, ism: h ii regions, ism: individual name: orion nebula, radio continuum: ism, shock waves
CODE: ristorcelli98