L-band (3.5 mu m) IR-excess in massive star formation I. 30 Doradus

Abstract

L-band data of 30 Doradus at 3.5 mu m taken with SPIREX (South Pole Infrared Explorer) is presented. The photometry was combined with 2MASS JHK data at 1.25- 2.2 mu m. Colour-colour and colour-magnitude diagrams are constructed and used to determine the sources with infrared excess. These are interpreted as circumstellar disks, and enable the fraction of sources with disks (the cluster disk fraction or CDF) to be determined. We find that similar to 42% of the sources detected at L-band in 30 Doradus have an IR-excess.