Letter to the Editor

Herschel observations of the W43 “mini-starburst”^*

¹ Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389 CASA, Boulder CO 80309-0389, USA e-mail: john.bally@colorado.edu
² Laboratoire d'Astrophysique de Marseille (UMR 6110 CNRS & Universitè de Provence), 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13, France
³ Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389 CASA, Boulder CO 80309-0389, USA
⁴ ASI Science Data Center, 00044 Frascati (Rome), Italy
⁵ Istituto Fisica Spazio Interplanetario INAF, via Fosso del Cavaliere 100, 00133 Roma, Italy
⁶ ASI Science Data Center, 00044 Frascati (Rome), Italy
⁷ Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389 CASA, Boulder CO 80309-0389, USA
⁸ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
⁹ Laboratoire AIM, CEA/IRFU CNRS/INSU Université Paris Diderot, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
¹⁰ Istituto Fisica Spazio Interplanetario INAF, via Fosso del Cavaliere 100, 00133 Roma, Italy
¹¹ Laboratoire AIM, CEA/DSM - CNRS Université Paris Diderot, DAPNIA/Service d'Astrophysique, Bât. 709, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
¹² Dept. of Physics, University of Gothenburg, 412 96, Gteborg, Sweden
¹³ Department of Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
¹⁴ Laboratoire d'Astrophysique de Marseille (UMR 6110 CNRS & Université de Provence), 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13, France
¹⁵ I. Physikalisches Instiut der Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
¹⁶ Steward Observatory, University of Arizona, 933 North Cherry Ave., Tucson, AZ 85721, USA
¹⁷ SAp-CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France
¹⁸ Steward Observatory, University of Arizona, 933 North Cherry Ave., Tucson, AZ 85721, USA
¹⁹ Center for Astrophysics and Space Astronomy, University of Colorado, UCB 389 CASA, Boulder CO 80309-0389, USA
²⁰ European Southern Observatory, Karl Schwarzschild str. 2, 85748 Garching, Germany
²¹ Dipartimento di Fisica, Universit di Roma 2 “Tor Vergata”, Rome, Italy
²² Dipartimento di Fisica, Universit di Roma 1 “La Sapienza”, Rome, Italy
²³ Laboratoire d'Astrophysique de Marseille (UMR 6110 CNRS & Université de Provence), 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13, France

Received: 31 March 2010
Accepted: 5 May 2010

Abstract

Aims. To explore the infrared and radio properties of one of the closest Galactic starburst regions.

Methods. Images obtained with the Herschel Space Observatory at wavelengths of 70, 160, 250, 350, and 500 μm using the PACS and SPIRE arrays are analyzed and compared with radio continuum VLA data and 8 μm images from the Spitzer Space Observatory. The morphology of the far-infrared emission is combined with radial velocity measurements of millimeter and centimeter wavelength transitions to identify features likely to be associated with the W43 complex.

Results. The W43 star-forming complex is resolved into a dense cluster of protostars, infrared dark clouds, and ridges of warm dust heated by massive stars. The 4 brightest compact sources with L > 1.5 × 10⁴  embedded within the Z-shaped ridge of bright dust emission in W43 remain single at 4” (0.1 pc) resolution These objects, likely to be massive protostars or compact clusters in early stages of evolution are embedded in clumps with masses of 10³ to 10⁴ , but contribute only 2% to the 3.6 × 10⁶  far-IR luminosity of W43 measured in a 16 by 16 pc box. The total mass of gas derived from the far-IR dust emission inside this region is ~10⁶ . Cometary dust clouds, compact 6 cm radio sources, and warm dust mark the locations of older populations of massive stars. Energy release has created a cavity blowing-out below the Galactic plane. Compression of molecular gas in the plane by the older H ii region near G30.684–0.260 and the bipolar structure of the resulting younger W43 H ii region may have triggered the current mini-star burst.