Letter to the Editor

The Herschel first look at protostars in the Aquila rift^*

¹ Laboratoire AIM, CEA/DSM–CNRS–Université Paris Diderot, IRFU/Service d'Astrophysique, C.E. Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France
² CNRS/INSU, Laboratoire d'Astrophysique de Bordeaux, UMR 5804, BP 89, 33271 Floirac cedex, France e-mail: bontemps@obs.u-bordeaux1.fr
³ Université de Bordeaux, OASU, Bordeaux, France
⁴ European Southern Observatory, Karl Schwarzschild Str. 2, 85748 Garching, Germany
⁵ INAF-IFSI, Fosso del Cavaliere 100, 00133 Roma, Italy
⁶ IAS, CNRS-INSU-Université Paris-Sud, 91435 Orsay, France
⁷ Laboratoire d'Astrophysique de Marseille, CNRS/INSU-Université de Provence, 13388 Marseille Cedex 13, France
⁸ CESR & UMR 5187 du CNRS/Université de Toulouse, BP 4346, 31028 Toulouse Cedex 4, France
⁹ Observatoire astronomique de Strasbourg, UMR 7550 CNRS/Université de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France
¹⁰ IRAM, 300 rue de la Piscine, Domaine Universitaire, 38406 Saint-Martin-d'Hères, France
¹¹ National Research Council of Canada, Herzberg Institute of Astrophysics, University of Victoria, Department of Physics and Astronomy, Victoria, Canada
¹² School of Physics and Astronomy, Cardiff University, Queens Buildings The Parade, Cardiff CF24 3AA, UK
¹³ National Astronomical Observatories, Chinese Academy of Sciences, 100012 Beijing, PR China
¹⁴ CITA & Dep. of Astronomy and Astrophysics, University Toronto, Toronto, Canada
¹⁵ Herschel Science Center, ESAC, ESA, PO Box 78, Villanueva de la Cañada, 28691 Madrid, Spain
¹⁶ Department of Astronomy, Stockholm Observatoty, AlbaNova University Center, Roslagstullsbacken 21, 10691 Stockholm, Sweden
¹⁷ Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre et Marie Curie, 98 bis Boulevard Arago, 75014 Paris, France
¹⁸ Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, EH9 3HJ, UK
¹⁹ INAF-Osservatorio Astrofisico di Arcetri, Largo Fermi 5, 50125 Firenze, Italy
²⁰ Science and Technology Facilities Council, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0NL, UK
²¹ Department of Physics & Astronomy, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
²² Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada
²³ SUPA, Institute for Astronomy, Edinburgh University, Blackford Hill, Edinburgh EH9 3HJ, UK

Received: 31 March 2010
Accepted: 13 April 2010

Abstract

As part of the science demonstration phase of the Herschel mission of the Gould Belt key program, the Aquila rift molecular complex has been observed. The complete ~ 3.3° × 3.3° imaging with SPIRE 250/350/500 μm and PACS 70/160 μm allows a deep investigation of embedded protostellar phases, probing of the dust emission from warm inner regions at 70 and 160 μm to the bulk of the cold envelopes between 250 and 500 μm. We used a systematic detection technique operating simultaneously on all Herschel bands to build a sample of protostars. Spectral energy distributions are derived to measure luminosities and envelope masses, and to place the protostars in an M_env – L_bol evolutionary diagram. The spatial distribution of protostars indicates three star-forming sites in Aquila, with W40/Sh2-64 HII region by far the richest. Most of the detected protostars are newly discovered. For a reduced area around the Serpens South cluster, we could compare the Herschel census of protostars with Spitzer results. The Herschel protostars are younger than in Spitzer with 7 Class 0 YSOs newly revealed by Herschel. For the entire Aquila field, we find a total of ~45–60 Class 0 YSOs discovered by Herschel. This confirms the global statistics of several hundred Class 0 YSOs that should be found in the whole Gould Belt Survey.