Letter to the Editor

Physical properties of the Sh2-104 H II region as seen by Herschel^*

¹ Laboratoire d'Astrophysique de Marseille (UMR 6110 CNRS and Université de Provence), 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13, France e-mail: jarodon@oamp.fr
² Institute for Space Imaging Science, University of Lethbridge, Lethbridge, Canada
³ Space Science Department, Rutherford Appleton Laboratory, Chilton, UK
⁴ Institut d'Astrophysique Spatiale, CNRS/Université Paris-Sud 11, 91405 Orsay, France
⁵ CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, 91191 Gif-sur-Yvette, France
⁶ CNRS/INSU, Laboratoire d'Astrophysique de Bordeaux, UMR 5804, BP 89, 33271 Floirac Cedex, France
⁷ Department of Physics and Astronomy, Cardiff University, UK
⁸ Infrared Processing & Analysis Center, California Institute of Technology, Mail Code 100-22, 770 South Wilson Av, Pasadena, CA 91125, USA
⁹ Universié de Toulouse; UPS; CESR; and CNRS; UMR5187, 9 avenue du colonel Roche, 31028 Toulouse Cedex 4, France
¹⁰ Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, M5S 3H8, Canada
¹¹ University of California, Radio Astronomy Laboratory, Berkeley, 601 Campbell Hall, US Berkeley CA 94720-3411, USA
¹² Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint-Martin-d'Hères, France
¹³ National Astronomical Observatories, PR China
¹⁴ Blue Sky Spectrosocpy Inc, Lethbridge, Canada
¹⁵ Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
¹⁶ Istituto di Fisica dello Spazio Interplanetario, INAF, via del Fosso del Cavaliere 100, 00133 Roma, Italy
¹⁷ NASA – Goddard SFC, USA
¹⁸ Laboratoire des Signaux et Systèmes (CNRS & Supélec & Université Paris-Sud 11), Moulon, 91192 Gif-sur-Yvette, France
¹⁹ Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Kent, UK
²⁰ Department of Physics & Astronomy, The Open University, Milton Keynes MK7 6AA, UK

Received: 31 March 2010
Accepted: 7 May 2010

Abstract

Context. Sh2-104 is a Galactic H ii region with a bubble morphology, detected at optical and radio wavelengths. It is considered the first observational confirmation of the collect-and-collapse model of triggered star-formation.

Aims. We aim to analyze the dust and gas properties of the Sh2-104 region to better constrain its effect on local future generations of stars. In addition, we investigate the relationship between the dust emissivity index β and the dust temperature, T_dust.

Methods. Using Herschel PACS and SPIRE images at 100, 160, 250, 350 and 500 μm we determine T_dust and β throughout Sh2-104, fitting the spectral energy distributions (SEDs) obtained from aperture photometry. With the SPIRE Fourier-transform spectrometer (FTS) we obtained spectra at different positions in the Sh2-104 region. We detect J-ladders of ¹²CO and ¹³CO, with which we derive the gas temperature and column density. We also detect proxies of ionizing flux as the [Nii] ³P₁-³P₀ and [Ci] ³P₂–³P₁ transitions.

Results. We find an average value of β ~ 1.5 throughout Sh2-104, as well as a T_dust difference between the photodissociation region (PDR, ~25 K) and the interior (~40 K) of the bubble. We recover the anti-correlation between β and dust temperature reported numerous times in the literature. The relative isotopologue abundances of CO appear to be enhanced above the standard ISM values, but the obtained value is very preliminary and is still affected by large uncertainties.