Pre-Main Sequence Turn-On as a Chronometer for Young Clusters

M. Cignoni; M. Tosi; E. Sabbi; A. Nota; S. Degl’Innocenti; P.G. Prada Moroni; J.S. Gallagher

doi:10.1051/eas/1148073

All issues

Volume 48 (2011)

EAS Publications Series, 48 (2011) 311-312

Abstract

Issue		EAS Publications Series Volume 48, 2011 CRAL-2010 A Universe of Dwarf Galaxies


Page(s)		311 - 312
Section		Distribution and Luminosity Functions of Dwarfs
DOI		https://doi.org/10.1051/eas/1148073
Published online		11 July 2011

A Universe of Dwarf Galaxies
M. Koleva, Ph. Prugniel and I. Vauglin (eds)
EAS Publications Series, 48 (2011) 311–312

Pre-Main Sequence Turn-On as a Chronometer for Young Clusters

M. Cignoni¹^,2, M. Tosi², E. Sabbi³, A. Nota³^,4, S. Degl’Innocenti⁵^,6, P.G. Prada Moroni⁵^,6 and J.S. Gallagher⁷

¹ Dipartimento di Astronomia, via Ranzani 1, 40127 Bologna, Italy
² INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
³ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, USA
⁴ European Space Agency, Research and Scientific Support Department, Baltimore, USA
⁵ Dipartimento di Fisica, Università di Pisa, largo Pontecorvo 3, Pisa 56127, Italy
⁶ INFN – Sezione di Pisa, largo Pontecorvo 3, Pisa 56127, Italy
⁷ University of Wisconsin, Madison, WI, USA

Abstract

We present a new approach to estimate the ages of very young clusters based on the Pre-Main Sequence (PMS) Turn-On (TOn), point in the colour magnitude diagram where the PMS joins the main sequence (MS). In order to detect the TOn magnitude, we propose to monitor the spatial distribution of MS stars: any drop in the MS spatial density is a necessary signature for a successful TOn identification and, accordingly, a robust cluster dating. We use Hubble Space Telescope photometry of the star forming region NGC 346 as a benchmark for the method.