Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-17T16:27:32.596Z Has data issue: false hasContentIssue false

Chemical Tracers of Pre-Brown Dwarf Cores Formed Through Turbulent Fragmentation

Published online by Cambridge University Press:  12 September 2016

Jonathan Holdship
Affiliation:
Department of Physics and Astronomy, University College London, WC1E 6BT, United Kingdom email: jrh@star.ucl.ac.uk
Serena Viti
Affiliation:
Department of Physics and Astronomy, University College London, WC1E 6BT, United Kingdom email: jrh@star.ucl.ac.uk
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

A gas-grain time dependent chemical code, UCL_CHEM, has been used to investigate the possibility of using chemical tracers to differentiate between the possible formation mechanisms of brown dwarfs. We model the formation of a pre-brown dwarf core through turbulent fragmentation by following the depth-dependent chemistry in a molecular cloud through the step change in density associated with an isothermal shock and the subsequent freefall collapse once a bound core is produced. Trends in the fractional abundance of molecules commonly observed in star forming cores are then explored to find a diagnostic for identifying brown dwarf mass cores formed through turbulence. We find that the cores produced by our models would be bright in CO and NH3 but not in HCO+. This differentiates them from models using purely freefall collapse as such models produce cores that would have detectable transitions from all three molecules.

Type
Poster Papers
Copyright
Copyright © International Astronomical Union 2016 

References

Padoan, P. & Nordlund, Å. 2002, ApJ, 576, 870 CrossRefGoogle Scholar
Rebolo, R., Zapatero Osorio, M. R. & Martín, E. L. 1995, Nature, 377, 129 Google Scholar
Schier, F.L., van der Tak, F.F.S., van Dishoeck, E.F., Black, J. H. 2005, A&A 432, 369 Google Scholar
Van der Tak, F.F.S., Black, J.H., Schier, F.L., Jansen, D.J., van Dishoeck, E.F., 2007, A&A 468, 627 Google Scholar
Viti, S., Collings, M.P., Dever, J.W., McCoustra, M.R.S. & Williams, D. A. 2004, MNRAS, 354, 1141 Google Scholar