Evolutionary view through the starless cores in Taurus: Deuteration in TMC 1-C and TMC 1-CP
Artikel i vetenskaplig tidskrift, 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

Observatorio Astronómico Nacional (OAN)

A. Fuente

Observatorio Astronómico Nacional (OAN)

L. Majumdar

National Institute of Science Education and Research

V. Wakelam

Université de Bordeaux

P. Caselli


P. Riviere-Marichalar

Observatorio Astronómico Nacional (OAN)

Sandra Treviño Morales

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Extragalaktisk astrofysik

S. Cazaux

TU Delft

Universiteit Leiden

I. Jimenez-Serra

Centro de Astrobiologia (CAB)

C. Kramer

Institut de Radioastronomie Millimétrique (IRAM)

A. Chacón-Tanarro

Observatorio Astronómico Nacional (OAN)

J. Kirk

University of Central Lancashire

D. Ward-Thompson

University of Central Lancashire

M. Tafalla

Observatorio Astronómico Nacional (OAN)

Astronomy and Astrophysics

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

Vol. 653 A15


Astronomi, astrofysik och kosmologi

Annan fysik




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