Evolutionary view through the starless cores in Taurus: Deuteration in TMC 1-C and TMC 1-CP
Journal article, 2021

Context. The chemical and physical evolution of starless and pre-stellar cores are of paramount importance to understanding the process of star formation. The Taurus Molecular Cloud cores TMC 1-C and TMC 1-CP share similar initial conditions and provide an excellent opportunity to understand the evolution of the pre-stellar core phase. Aims. We investigated the evolutionary stage of starless cores based on observations towards the prototypical dark cores TMC 1-C and TMC 1-CP. Methods. We mapped the prototypical dark cores TMC 1-C and TMC 1-CP in the CS 3 → 2, C34S 3 → 2, 13CS 2 → 1, DCN 1 → 0, DCN 2 → 1, DNC 1 → 0, DNC 2 → 1, DN13C 1 → 0, DN13C 2 → 1, N2H+ 1 → 0, and N2D+ 1 → 0 transitions. We performed a multi-transitional study of CS and its isotopologs, DCN, and DNC lines to characterize the physical and chemical properties of these cores. We studied their chemistry using the state-of-the-art gas-grain chemical code NAUTILUS and pseudo time-dependent models to determine their evolutionary stage. Results. The central nH volume density, the N2H+ column density, and the abundances of deuterated species are higher in TMC 1-C than in TMC 1-CP, yielding a higher N2H+ deuterium fraction in TMC 1-C, thus indicating a later evolutionary stage for TMC 1-C. The chemical modeling with pseudo time-dependent models and their radiative transfer are in agreement with this statement, allowing us to estimate a collapse timescale of ~1 Myr for TMC 1-C. Models with a younger collapse scenario or a collapse slowed down by a magnetic support are found to more closely reproduce the observations towards TMC 1-CP. Conclusions. Observational diagnostics seem to indicate that TMC 1-C is in a later evolutionary stage than TMC 1-CP, with a chemical age ~1 Myr. TMC 1-C shows signs of being an evolved core at the onset of star formation, while TMC 1-CP appears to be in an earlier evolutionary stage due to a more recent formation or, alternatively, a collapse slowed down by a magnetic support.

Stars: formation

ISM: abundances

ISM: kinematics and dynamics

Stars: low-mass

ISM: molecules



D. Navarro-Almaida

Spanish National Observatory (OAN)

A. Fuente

Spanish National Observatory (OAN)

L. Majumdar

National Institute of Science Education and Research

V. Wakelam

University of Bordeaux

P. Caselli

Max Planck Society

P. Riviere-Marichalar

Spanish National Observatory (OAN)

Sandra Treviño Morales

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Extragalactic Astrophysics

S. Cazaux

Delft University of Technology

Leiden University

I. Jimenez-Serra

Centro de Astrobiologia (CAB)

C. Kramer

Institut de Radioastronomie Millimétrique (IRAM)

A. Chacón-Tanarro

Spanish National Observatory (OAN)

J. Kirk

University of Central Lancashire

D. Ward-Thompson

University of Central Lancashire

M. Tafalla

Spanish National Observatory (OAN)

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 653 A15

Subject Categories

Astronomy, Astrophysics and Cosmology

Other Physics Topics




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