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Cold Dark Clouds: The Initial Conditions for Star Formation
AbstractCold dark clouds are nearby members of the densest and coldest phase in the Galactic interstellar medium, and represent the most accessible sites where stars like our Sun are currently beingExpand
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Dense Cores in Dark Clouds. XIV. N2H+ (1-0) Maps of Dense Cloud Cores
We present results of an extensive mapping survey of N2H+ (1-0) in about 60 low-mass cloud cores already mapped in the NH3 (1, 1) inversion transition line. The survey has been carried out at theExpand
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On the internal structure of starless cores - I. Physical conditions and the distribution of CO, CS, N$\mathsf{_2}$H$\mathsf{^+}$, and NH$\mathsf{_3}$ in L1498 and L1517B
We have characterized the physical structure and chemical composition of two close-to-round starless cores in Taurus-Auriga, L1498 and L1517B. Our analysis is based on high angular resolutionExpand
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Cores, filaments, and bundles: hierarchical core formation in the L1495/B213 Taurus region
Context. Core condensation is a critical step in the star-formation process, but it is still poorly characterized observationally. Aims. We have studied the 10 pc-long L1495/B213 complex in Taurus toExpand
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A Search for Infall Motions toward Nearby Young Stellar Objects
We report observations of 47 candidate protostars in two optically thick lines [H2CO (212-111) and CS (2-1)] and one optically thin line [N2H+ (1-0)] using the IRAM 30 m, SEST 15 m, and Haystack 37 mExpand
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Systematic Molecular Differentiation in Starless Cores
We present evidence that low-mass starless cores, the simplest units of star formation, are systematically differentiated in their chemical composition. Some molecules, including CO and CS, almostExpand
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Probing the Evolutionary Status of Starless Cores through N2H+ and N2D+ Observations
We have undertaken a survey of N2H+ and N2D+ toward 31 low-mass starless cores using the IRAM 30 m telescope. Our main objective has been to determine the abundance ratio of N2D+ and N2H+ toward theExpand
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Molecular Ions in L1544. II. The Ionization Degree
The maps presented in Paper I are here used to infer the variation of the column densities of HCO+, DCO+, N2H+, and N2D+ as a function of distance from the dust peak. These results are interpretedExpand
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A Simple Model of Spectral-Line Profiles from Contracting Clouds
A simple analytic model of radiative transfer in two parts of a contracting cloud matches a wide range of line profiles in candidate infall regions and provides a sensitive estimate of Vin, theExpand
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Molecular ions in L1544. I. Kinematics
We have mapped the dense dark core L1544 in H13CO+(1-0), DCO+(2-1), DCO+(3-2), N2H+(1-0), NTH+(3-2), N2D+(2-1), N2D+(3-2), C18O(1-0), and C17O(1-0) using the IRAM 30-m telescope. We have obtainedExpand
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