Analysis of the emission of very small dust particles from Spitzer spectro-imagery data using blind signal separation methods

By Olivier Berné, Christine Joblin, Yannick Deville, John-David T. Smith, Mathias Rapacioli, J. Bernard, J. Thomas, W. Reach, Alain Abergel. 2007

186 citations recorded by the source corpus.

Context: This work was conducted as part of the SPECPDR program, dedicated to the study of very small particles and astrochemistry, in Photo-Dissociation Regions (PDRs). Aims: We present the analysis of the mid-IR spectro-imagery observations of Ced 201, NCG 7023 East and North-West and ? Ophiuchi West filament. Methods: Using the data from all four modules of the InfraRed Spectrograph onboard the Spitzer Space Telescope, we produced a spectral cube ranging from 5 to 35 ?m, for each one of the observed PDRs. The resulting cubes were analysed using Blind Signal Separation methods (NMF and FastICA). Results: For Ced 201, ? Ophiuchi West filament and NGC 7023 East, we find that two signals can be extracted from the original data cubes, which are 5 to 35 ?m spectra. The main features of the first spectrum are a strong continuum emission at long wavelengths, and a broad 7.8 ?m band. On the contrary, the second spectrum exhibits the classical Aromatic Infrared Bands (AIBs) and no continuum. The reconstructed spatial distribution maps show that the latter spectrum is mainly present at the cloud surface, close to the star whereas the first one is located slightly deeper inside the PDR. The study of the spectral energy distribution of Ced 201 up to 100 ?m suggests that, in cool PDRs, the 5-25 ?m continuum is carried by Very Small Grains (VSGs). The AIB spectra in the observed objects can be interpreted as the contribution of neutral and positively-charged Polycyclic Aromatic Hydrocarbons (PAHs). Conclusions: We extracted the 5 to 25 ?m emission spectrum of VSGs in cool PDRs, these grains being most likely carbonaceous. We show that the variations of the mid-IR (5-35 ?m) spectra of PDRs can be explained by the photo-chemical processing of these VSGs and PAHs, VSGs being the progenitors of free PAHs. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Spectra are only available in electronic form (FITS files) at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/469/575

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/028715d9d205cb23def900c5e05503187ae0ccf5

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

The Behavior of the Aromatic Features in M101 H II Regions: Evidence for Dust Processing (2008, background): “There has been ample evidence for such processing in spatially resolved studies in reflection nebulae and HII regions in the Milky Way (Cesarsky et al. 2000; Berné et al. 2007).”
The global dust SED: tracing the nature and evolution of dust with DustEM (2010, background): “…abundance betweenth PAH band emitters and the mid-IR continuum emitters (SamC in our 6 This process has been shown to alter the sub-mm opacity by factors 2 to 3 (Stepnik et al. 2003; Paradis et al. 2009a). case) is known to vary (e.g Berné et al. 2007; Compiègne et al. 2008; Flagey et al. 2009).”
Non-standard grain properties, dark gas reservoir, and extended submillimeter excess, probed by Herschel in the Large Magellanic Cloud (2011, background): “…of the grain size distribution (Draine, 2003a; Fitzpatrick & Massa, 2005); (iii) coagulation occurs in dense regions (e.g. Stepnik et al., 2003; Berné et al., 2007); (iv) blast waves are responsible for grain fragmentation and erosion in the low-velocity phase (Jones et al., 1996) and…”
Polycyclic aromatic hydrocarbon processing in interstellar shocks (2009, background): “The observed spectra also show evidence for PAH clusters containing a few hundred C-atoms (Bregman et al. 1989; Rapacioli et al. 2005; Berné et al. 2007) as well as very small dust grains (∼30 Å; Désert et al. 1990).”
THE INFRARED SPECTRA OF VERY LARGE IRREGULAR POLYCYCLIC AROMATIC HYDROCARBONS (PAHs): OBSERVATIONAL PROBES OF ASTRONOMICAL PAH GEOMETRY, SIZE, AND CHARGE (2009, background): “…vary between different objects and spatially within extended objects (e.g., Peeters et al. 2002a, 2004; Bregman & Temi 2005; Rapacioli et al. 2005; Berné et al. 2007; Sellgren et al. 2007, and references therein), revealing the nature of the specific PAH molecules present and reflecting the…”