منابع مشابه
Dense Star-forming Gas and Dust in the Magellanic Clouds
The early stages of the star formation process are closely related to the condition of the parent interstellar medium, in particular to the heating/cooling balance, which itself is a function of ambient conditions. Important questions such as dust abundance, size distribution, temperature distribution, fraction of molecular gas, fraction of dense gas, gas surface density and total amount of gas...
متن کاملDetermination of the gas-to-dust ratio in nearby dense clouds using X-ray absorption measurements
We present a comparison of the gas and dust properties of the dense interstellar matter in six nearby star−forming regions (d <500 pc): ρ Oph, Cha I, R CrA, IC 348, NGC 1333, and Orion. We measure from Chandra and XMM−Newton observations the X-ray absorption toward pre-main sequence stars (PMS) without accretion disks (i.e., Class III sources) to obtain the total hydrogen column density NH,X. F...
متن کاملChlorine in Dense Interstellar Clouds: the Abundance
We report the first detection of a chlorine-bearing molecular species in the interstellar medium via emission from the J = 1----> 0 transition of HCl at 625.9 GHz toward OMC-1. The relative strengths, widths, and velocities of the resolved hyperfine components are consistent with moderate optical depth emission originating from dense, quiescent molecular cloud material (VLsR = 9 km s1). The ove...
متن کاملAstrophysics of Dust in Cold Clouds
Dust plays an increasingly important role in astrophysics. Historically, dust was first recognized for its obscuring effects, and the need to correct observed intensities for attenuation by dust continues today. But with the increasing sensitivity of IR, FIR, and submm telescopes, dust is increasingly important as a diagnostic, with its emission spectrum providing an indicator of physical condi...
متن کاملObservations of in Dense Molecular Clouds
has been detected using infrared absorption spectroscopy along the lines of sight to six infrared 3 sources in dense molecular clouds : AFGL 2136, W33A, Mon R2 IRS 3, AFGL 961E, AFGL 2591, and AFGL 490. Upper limits to the column densities of are reported for an additional nine sources. The 3 column densities of CO toward Mon R2 IRS 3 and AFGL 961E have been determined from observations of the ...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1989
ISSN: 0074-1809
DOI: 10.1017/s0074180900125276