HiNarrow Self‐Absorption in Dark Clouds
نویسندگان
چکیده
منابع مشابه
Ammonia in Infrared Dark Clouds
Context. While low mass clouds have been relatively well studied, our picture of high-mass star formation remains unclear. Infrared Dark Clouds appear to be the long sought population of cold and dense aggregations with the potential of harbouring the earliest stages of massive star formation. Up to now there has been no systematic study on the temperature distribution, velocity fields, chemica...
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We have used the Arecibo telescope to carry out an unbiased survey of 31 dark clouds in the Taurus/Perseus region for narrow absorption features in HI (λ 21cm) and OH (1667 and 1665 MHz) emission. We detected HI narrow line absorption (HINLA) in about 80% of the clouds that we observed. HINLA and OH emission, observed simultaneously are remarkably well correlated. Spectrally, they have the same...
متن کاملHI Narrow Self–Absorption in Dark Clouds
We have used the Arecibo telescope to carry out an survey of 31 dark clouds in the Taurus/Perseus region for narrow absorption features in HI (λ 21cm) and OH (1667 and 1665 MHz) emission. We detected HI narrow self–absorption (HINSA) in 77% of the clouds that we observed. HINSA and OH emission, observed simultaneously are remarkably well correlated. Spectrally, they have the same nonthermal lin...
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Received ; accepted – 2 – ABSTRACT The present work investigates the parametric instability of parallel propagating circularly polarized Alfvén (pump) waves in a weakly ionized molecular cloud. It is shown that the relative drift between the plasma particles gives rise to the Hall effect resulting in the modified pump wave characteristics. Although the linearized fluid equations with periodic c...
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We discuss the problem of a consistent determination of the visual extinction to objects in and behind a dark cloud. The use of near-infrared colours is discussed, in particular the H-K colours. We concentrate on the uncertainties, with emphasis on the extinction law and on the intrinsic colours of the young stars embedded in a dark cloud. The cases of the two intensively studied nearby star-fo...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2003
ISSN: 0004-637X,1538-4357
DOI: 10.1086/346227