ISOGAL: A deep survey of the obscured inner Milky Way with ISO at 7 μm and 15 μm and with DENIS in the near-infrared

Abstract

Abstract. The ISOGAL project is an infrared survey of specific regions sampling the Galactic Plane selected to provide information on Galactic structure, stellar populations, stellar mass-loss and the recent star formation history of the inner disk and Bulge of the Galaxy. ISOGAL combines 7 and 15 µm ISOCAM observations -with a resolution of 6 at worst -with DENIS IJK s data to determine the nature of the sources and the interstellar extinction. We have observed about 16 square degrees with a sensitivity approaching 10-20 mJy, detecting ∼10 5 sources, mostly AGB stars, red giants and young stars. The main features of the ISOGAL survey and the observations are summarized in this paper, together with a brief discussion of data processing and quality. The primary ISOGAL products are described briefly (a full desciption is given in Schuller et al. 2003): viz. the images and the ISOGAL-DENIS five-wavelength point source catalogue. The main scientific results already derived or in progress are summarized. These include astrometrically calibrated 7 and 15 µm images, determining structures of resolved sources; identification and properties of interstellar dark clouds; quantification of the infrared extinction law and source dereddening; analysis of red giant and (especially) AGB stellar populations in the central Bulge, determining luminosity, presence of circumstellar dust and mass-loss rate, and source classification, supplemented in some cases by ISO/CVF spectroscopy; detection of young stellar objects of diverse types, especially in the inner Bulge with information about the present and recent star formation rate; identification of foreground sources with mid-IR excess. These results are the subject of about 25 refereed papers published or in preparation.

Clouds, filaments, and protostars: TheHerschel Hi-GAL Milky Way

“…Since then, a continuing explosion of Galactic plane surveys, Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. both in the mid-infrared at λ ≤ 70 μm (Omont et al 2003;Price et al 2001;Benjamin et al 2003;Carey et al 2009) and in the submillimeter at λ ≥ 800 μm (Schuller et al 2009;Rosolowsky et al 2009), are assembling a picture where the galactic plane has become accessible at sub-30 resolution over three decades of wavelength. The exception is the critical interval between 70 and 500 μm where the bulk of the cold dust in the Galaxy emits and reaches the peak of its spectral energy distribution (SED).…”

Recent star formation in the inner Galactic bulge seen by ISOGAL

“…Article published by EDP Sciences A121, page 1 of 19 Omont et al 2003) with known natures, dividing them into young objects 1 (YOs) and late-type evolved objects (LEOs). Since YOs are embedded in a dust cocoon, they appear more extended at 15 μm than LEOs.…”

Tracing the energetics and evolution of dust withSpitzer: a chapter in the history of the Eagle Nebula

“…The mid-IR images of M 16 from either the Infrared Space Observatory CAMera (ISOCAM Cesarsky et al 1996a) at 8 and 15 μm (Pilbratt et al 1998;Omont et al 2003) or based on the combined Spitzer observations using IRAC 8 μm (Fazio et al 2004) and MIPS 24 μm (Rieke et al 2004), show a shell-like emission at 15 and 24 μm that fills the nebula cavity (Flagey et al 2009a), as delineated by the shorter IR wavelengths and the extent of the H α emission. The shell stands out in the ISO 15 μm and MIPS 24 μm images, while the Nebula pillars and the outer rim of the nebula are the strongest emission features at 8 μm.…”