Near-infrared variability in the star-forming region RCW 38⋆
1 Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
2 Instituto de Astronomía, Universidad Católica del Norte, Antofagasta, Chile
Received: 30 August 2012
Accepted: 11 March 2013
Aims. We want to study the content of young stellar objects in the RCW 38 cluster by means of multi-epoch variability studies.
Methods. We performed a three-month near-infrared (NIR) monitoring campaign of the young cluster RCW 38 using the 80 cm IRIS telescope near Cerro Armazones, Chile. Variability data with a median sampling of 1 day was gathered for 1026 sources, while a total of 3433 sources in JHK could be studied in the co-added, deep images with a completeness limit of K < 15 mag.
Results. We find that 139 sources were identified as variable with amplitudes above 10% in H and K, and 47% of these variables have been classified as candidate young stars by previous X-ray and mid-infrared studies. Although the majority of the variable sources show no K-excess, their high extinction and concentration towards the cluster center, together with their irregular variability behavior, suggest that they are also candidate young stellar objects. Most of them are likely low-mass sources with variability amplitudes typical of T Tauri stars. The majority of previously suggested OB candidates appear to be intermediate-mass pre-main sequence sources on the basis of their JHK properties.
Conclusions. NIR variability is an efficient tool for detecting new, embedded, young stellar objects that have escaped previous X-ray and mid-infrared studies.
Key words: stars: formation / stars: pre-main sequence / stars: variables: T Tauri, Herbig Ae/Be / stars: early-type / stars: late-type / open clusters and associations: individual: RCW 38
Full Tables 1 and 2 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/553/A48
© ESO, 2013