Carbon-Chain and Organic Molecules around Very Low-Luminosity Protostellar Objects of L1521F-IRS and IRAM 04191+1522

Abstract

We have observed dense gas around the Very Low-Luminosity Ob jects (VeLLOs) L1521F-IRS and IRAM 04191+1522 in carbon-chain and organic molecular lines with the Nobeyama 45 m telescope. Towards L1521F-IRS, carbon-chain lines of CH3CCH (50-40), C4H (17/2-15/2), and C3H2 (212-101) are 1.5 - 3.5 times stronger than those towards IRAM 04191+1522, and the abundances of the carbon-chain molecules towards L1521F-IRS are 2 to 5 times higher than those towards IRAM 04191+1522. Mapping observations of these carbon-chain molecular lines show that in L1521F the peak positions of these carbon-chain molecular lines are different from each other and there is no emission peak towards the VeLLO position, while in IRAM 04191+1522 these carbon-chain lines are as weak as the detection limits except for the C3H2 line. The observed chemical differentiation between L1521F and IRAM 04191+1522 suggests that the evolutionary stage of L1521F-IRS is younger than that of IRAM 04191+1522, consistent with the extent of the associated outflows seen in the 13CO (1-0) line. The non-detection of the organic molecular lines of CH3OH (6-2-7-1 E) and CH3CN (60-50) implies that the warm (~ 100 K) molecular-desorbing region heated by the central protostar is smaller than ~ 100 AU towards L1521F-IRS and IRAM 04191+1522, suggesting the young age of these VeLLOs. We propose that the chemical status of surrounding dense gas can be used to trace the evolutionary stages of VeLLOs.

25 pages, 4 figures

References in corpus (7)

• Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Linear Dynamic Range Spectral Line Mapping
• Identifying the Low Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores
• Molecular Evolution and Star Formation: From Prestellar Cores to Protostellar Cores
• An interferometric study of the low-mass protostar IRAS 16293-2422: small scale organic chemistry
• The Spitzer c2d Survey of Nearby Dense Cores: I: First Direct Detection of the Embedded Source in IRAM 04191+1522
• First Confirmed Detection of a Bipolar Molecular Outflow from a Young Brown Dwarf
• Far-infrared Observations of the Very Low-Luminosity Embedded Source L1521F-IRS in the Taurus Star-Forming Region

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• Organic chemistry of low-mass star-forming cores I: 7 mm spectroscopy of Chamaeleon MMS1
• The connection between warm carbon chain chemistry and interstellar irradiation of star-forming cores
• The Distinct Evolutionary Nature of two Class 0 Protostars in Serpens Main SMM4
• Spatial distribution of C4H and c-C3H2 in cold molecular cores
• The evolution of C4H and c-C3H2 in molecular cores