Halpha emission-line stars in molecular clouds. II. The M42 region

We present a deep survey of Halpha emission-line stars in the M42 region using wide-field objective prism films. A total of 1699 Halpha emission-line stars were identified, of which 1025 were previously unknown, within an area of 5.5 x 5.5 degrees centred on the Trapezium Cluster. We present Halpha strength estimates, positions, and JHKs photometry extracted from 2MASS, and comparisons to previous surveys. The spatial distribution of the bulk of the stars follows the molecular cloud as seen in CO and these stars are likely to belong to the very young population of stars associated with the Orion Nebula Cluster. Additionally, there is a scattered population of Halpha emission-line stars distributed all over the region surveyed, which may consist partly of foreground stars associated with the young NGC 1980 cluster, as well as some foreground and background dMe or Be stars. The present catalogue adds a large number of candidate low-mass young stars belonging to the Orion population, selected independently of their infrared excess or X-ray emission.Comment: 38 pages, 18 figures. Published in Astronomy & Astrophysics v3: chart for ESO-HA 1639 corrected. Typos in Table 2 corrected. Photometry for ESO-HA 1639 in Table 2 correcte

The VISCACHA survey-deep and resolved photometry of star clusters in the Magellanic Clouds

The VISCACHA (VIsible Soar photometry of star Clusters in tApii and Coxi HuguA†) Survey is an ongoing project based on deep and spatially resolved photometric observations of Magellanic Cloud star clusters, collected using the SOuthern Astrophysical Research (SOAR) telescope together with the SOAR Adaptive Module Imager. So far we have used >300h of telescope time to observe ∼150 star clusters, mostly with low mass (M < 104M⊠) on the outskirts of the LMC and SMC. With this high-quality data set, we homogeneously determine physical properties using deep colour-magnitude diagrams (ages, metallicities, reddening, distances, mass, luminosity and mass functions) and structural parameters (radial density profiles, sizes) for these clusters which are used as a proxy to investigate the interplay between the Magellanic Clouds and their evolution. We present the VISCACHA survey and its initial results, based on our first two papers. The project's long term goals and expected legacy to the community are also addressed.Fil: Dias, Bruno. European Southern Observatory Chile; Chile. Universidad Andrés Bello; ChileFil: Maia, Francisco. Universidade Federal do Rio de Janeiro; BrasilFil: Kerber, Leandro. Universidade Estadual de Santa Cruz; BrasilFil: Dos Santos, João F. C.. Universidade Federal de Minas Gerais; BrasilFil: Bica, Eduardo. Universidade Federal do Rio Grande do Sul; BrasilFil: Armond, Tina. Universidade Federal de São João del Rei; BrasilFil: Barbuy, Beatriz. Universidade de Sao Paulo; BrasilFil: Fraga, Luciano. Laboratório Nacional de Astrofísica; BrasilFil: Hernandez Jimenez, Jose A.. Universidad Andrés Bello; ChileFil: Katime Santrich, Orlando J.. Universidade Estadual de Santa Cruz; BrasilFil: Oliveira, Raphael A. P.. Universidade de Sao Paulo; BrasilFil: Pérez Villegas, Angeles. Universidade de Sao Paulo; BrasilFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Quint, Bruno. Observatorio Gemini; ChileFil: Sanmartin, David. Observatorio Gemini; ChileFil: Angelo, Mateus S.. Centro Federal de Educação Tecnológica de Minas Gerais; BrasilFil: Souza, Stefano O.. Universidade de Sao Paulo; BrasilFil: Vieira, Rodrigo G.. Universidade de Sao Paulo; BrasilFil: Westera, Pieter. Universidad Federal Do Abc; BrasilFil: Parisi, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Geisler, Doug. Universidad de La Serena; Chile. Universidad de Concepción; ChileFil: Minniti, Dante. Universidad Andrés Bello; Chile. Millennium Institute of Astrophysics; Chile. Vatican Observatory; ItaliaFil: Saito, Roberto. Universidade Federal de Santa Catarina; BrasilFil: Bassino, Lilia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: de Bórtoli, Bruno Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Figueiredo, André. Universidade de Sao Paulo; BrasilFil: Rímulo, Leandro. Universidad de los Andes; Colombi