Research Note

Diluting the material forming the second generation stars in globular clusters: the contribution by unevolved stars

¹ INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy e-mail: raffaele.gratton@oapd.inaf.it
² INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy

Received: 17 May 2010
Accepted: 14 July 2010

Abstract

In this short communication we consider the possibility that stars less evolved than the polluters are the source of the dilution needed to explain the observed composition of second-generation globular cluster (GC) stars and the Na-O and Mg-Al anticorrelations. If these stars can lose 0.5–1% of their mass during the relevant epochs, there is enough diluting material to produce the observed anticorrelations. In this case, the original mass of proto-GCs was several tens times higher than the current mass of GCs. While not strictly impossible, this is a stringent hypothesis that needs more support. Should this scenario be found true, then the link between the primordial (first-generation) population in GC and the field population would be very strong.