Far-infrared/submillimetre properties of pre-stellar cores L1521E, L1521F and L1689B as revealed by the<i>Herschel</i>SPIRE instrument – I. Central positions

Makiwa, G.; Naylor, David; Wiel, M. H. D. van der; Ward-Thompson, Derek; Kirk, J. M.; Eyres, S. P. S.; Abergel, A.; Koehler, Melanie

doi:10.1093/mnras/stw428

Cited by 13 publications

(16 citation statements)

References 62 publications

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“…We note that recent Herschel/SPIRE Fourier Transform Spectrometer (FTS) measurements toward the center (∼30″) position of MC27/L1521F reported a dust temperature of 15.6 ± 05 K and a β of 0.8 ± 0.1 (Makiwa et al 2016), which are different from what we assumed. β toward MMS-1 is calculated to be small (∼0.4), with an angular extent of ∼1 3 × 0 8 in the present ALMA observations, and this fact may indicate that the inclusion of MMS-1 in a Herschel beam may be a cause of the low beta and high temperature.…”

Section: Resultscontrasting

confidence: 99%

Revealing a Detailed Mass Distribution of a High-Density Core Mc27/L1521f in Taurus With Alma

Tokuda

Onishi

Matsumoto

et al. 2016

ApJ

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We present the results of ALMA observations of dust continuum emission and molecular rotational lines toward a dense core MC27 (aka L1521F) in Taurus, which is considered to be at a very early stage of star formation. The detailed column density distributions on size scales from a few tens to ∼10,000 AU are revealed by combining the ALMA (12 m array + 7 m array) data with the published/unpublished single-dish data. The high angular resolution observations at 0.87 mm with a synthesized beam size of ∼0 74 × 0 32 reveal that a protostellar source, MMS-1, is not spatially resolved and lacks associated gas emission, while a starless high-density core, MMS-2, has substructures in both dust and molecular emission. The averaged radial column density distribution of the inner part of MC27/L1521F (r  3000 AU) is N H 2 ∼ -r 0.4 , clearly flatter than that of the outer part, ∼ -r 1.0 . The complex velocity/spatial structure obtained with previous ALMA observations is located inside the inner flatter region, which may reflect the dynamical status of the dense core.

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Section: Resultscontrasting

confidence: 99%

Revealing a Detailed Mass Distribution of a High-Density Core Mc27/L1521f in Taurus With Alma

Tokuda

Onishi

Matsumoto

et al. 2016

ApJ

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“…Given the uncertainties induced by the mass absorption coefficient (with β = 2.2, our value at 1.3 mm is 0.0024 cm 2 g −1 , half that adopted by Tafalla et al 2004 in their study), and the fact that the density profile results from fitting an azimuth average of the map, an agreement within a factor of two can be considered a good one. Our results agree well with those obtained by Makiwa et al (2016), although our study includes longer wavelength maps, thus providing tight constraints to the spectral index.…”

Section: Discussionsupporting

confidence: 89%

Sulfur gas-phase abundance in dense cores

Hily-Blant

Forêts

Fauré

et al. 2022

A&A

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The abundance of volatile sulfur in dense clouds is long-standing problem in studies of the physics and chemistry of star-forming regions. Sulfur is an important species because its low ionization potential may possibly make it an important charge carrier. The observed sulfur-bearing species in the gas-phase of dense clouds represent only a minor fraction of the cosmic sulfur abundance, which has been interpreted as a signature of sulfur depletion into ices at the surface of dust grains. However, atomic sulfur, which could be the main gas-phase carrier, cannot be observed directly in cold cores. We present measurements of the nitrogen sulfide (NS) radical toward four dense cores performed with the IRAM-30m telescope. Analytical chemical considerations and chemical models over a wide parameter space show that the NS:N2H+ abundance ratio provides a direct constraint on the abundance of gas-phase atomic sulfur. Toward early-type cores, we find that n(S)∕nH is close, or even equal, to the cosmic abundance of sulfur, 14 × 10−6, demonstrating that sulfur is not depleted and is atomic, which is in agreement with chemical models. More chemically evolved cores show sulfur depletion by factors up to 100 in their densest parts. In L1544, atomic sulfur depletion is shown to increase with increasing density. Future observations are needed to discover the solid-phase carrier of sulfur. The initial steps of the collapse of pre-stellar cores in the high sulfur abundance regime also need to be explored from their chemical and dynamical perspectives.

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“…The corresponding mass is 2.2 M . Our SPIRE image modeling results are consistent within a factor of two in column density with the analysis of SPIRE-FTS observations by Makiwa et al (2016).…”

Section: Dust Continuumsupporting

confidence: 87%

Detection of Complex Organic Molecules in Young Starless Core L1521E

Scibelli,

Shirley,

Vasyunin

et al. 2021

Preprint

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Determining the level of chemical complexity within dense starless and gravitationally bound prestellar cores is crucial for constructing chemical models, which subsequently constrain the initial chemical conditions of star formation. We have searched for complex organic molecules (COMs) in the young starless core L1521E, and report the first clear detection of dimethyl ether (CH 3 OCH 3 ), methyl formate (HCOOCH 3 ), and vinyl cyanide (CH 2 CHCN). Eight transitions of acetaldehyde (CH 3 CHO) were also detected, five of which (A states) were used to determine an excitation temperature to then calculate column densities for the other oxygen-bearing COMs. If source size was not taken into account (i.e., if filling fraction was assumed to be one), column density was underestimated, and thus we stress the need for higher resolution mapping data. We calculated L1521E COM abundances and compared them to other stages of low-mass star formation, also finding similarities to other starless/prestellar cores, suggesting related chemical evolution. The scenario that assumes formation of COMs in gas-phase reactions between precursors formed on grains and then ejected to the cold gas via reactive desorption was tested and was unable to reproduce observed COM abundances, with the exception of CH 3 CHO. These results suggest that COMs observed in cold gas are formed not by gas-phase reactions alone, but also through surface reactions on interstellar grains. Our observations present a new, unique challenge for existing theoretical astrochemical models.

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Far-infrared/submillimetre properties of pre-stellar cores L1521E, L1521F and L1689B as revealed by theHerschelSPIRE instrument – I. Central positions

Cited by 13 publications

References 62 publications

Revealing a Detailed Mass Distribution of a High-Density Core Mc27/L1521f in Taurus With Alma

Revealing a Detailed Mass Distribution of a High-Density Core Mc27/L1521f in Taurus With Alma

Sulfur gas-phase abundance in dense cores

Detection of Complex Organic Molecules in Young Starless Core L1521E

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