INAF, Osservatorio Astrofisico di Arcetri,
Largo E. Fermi 5, 50125
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2 INAF, Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
3 INAF, Istituto di Astrofisica e Planetologia Spaziale, Via Fosso del Cavaliere 100, 00133 Roma, Italy
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4 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 877, Ensenada, B. C., CP 22830, Mexico
5 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
6 INAF, Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monte Porzio Catone, Italy
7 Università degli Studi di Firenze, via Sansone 1, 50019 Sesto Fiorentino, Italy
8 Steward Observatory, The University of Arizona, 933 N. Cherry Ave., Tucson, TX 85721, USA
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Received: 27 March 2015
Accepted: 16 July 2015
Context. We present a study of the complex high-mass star forming region IRAS 05137+3919 (also known as Mol8), where multiple jets and a rich stellar cluster have been described in previous works.
Aims. Our goal is to determine the number of jets and shed light on their origin, and thus determine the nature of the young stars powering these jets. We also wish to analyse the stellar clusters by resolving the brightest group of stars.
Methods. The star forming region was observed in various tracers and the results were complemented with ancillary archival data. The new data represent a substantial improvement over previous studies both in resolution and frequency coverage. In particular, adaptive optics provides us with an angular resolution of 80 mas in the near IR, while new mid- and far-IR data allow us to sample the peak of the spectral energy distribution and thus reliably estimate the bolometric luminosity.
Results. Thanks to the near-IR continuum and millimetre line data we can determine the structure and velocity field of the bipolar jets and outflows in this star forming region. We also find that the stars are grouped into three clusters and the jets originate in the richest of these, whose luminosity is ~ 2.4 × 104L⊙. Interestingly, our high-resolution near-IR images allow us to resolve one of the two brightest stars (A and B) of the cluster into a double source (A1+A2).
Conclusions. We confirm that there are two jets and establish that they are powered by B-type stars belonging to cluster C1. On this basis and on morphological and kinematical arguments, we conclude that the less extended jet is almost perpendicular to the line of sight and that it originates in the brightest star of the cluster, while the more extended one appears to be associated with the more extincted, double source A1+A2. We propose that this is not a binary system, but a small bipolar reflection nebula at the root of the large-scale jet, outlining a still undetected circumstellar disk. The gas kinematics on a scale of ~0.2 pc seems to support our hypothesis, because it appears to trace rotation about the axis of the associated jet.
Key words: stars: early-type / stars: formation / ISM: jets and outflows
Based on observations carried out with the Large Binocular Telescope. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University of Virginia.
Appendix A is available in electronic form at http://www.aanda.org
© ESO, 2015