The blast view of the star-forming region in Aquila (ℓ = 45°, b = 0° )

We have carried out the first general submillimeter analysis of the field toward GRSMC 45.46+0.05, a massive star-forming region in Aquila. The deconvolved 6 deg^2 (3° × 2°) maps provided by BLAST in 2005 at 250, 350, and 500 μm were used to perform a preliminary characterization of the clump population previously investigated in the infrared, radio, and molecular maps. Interferometric CORNISH data at 4.8 GHz have also been used to characterize the Ultracompact H_II regions (UCH_(II)Rs) within the main clumps. By means of the BLAST maps, we have produced an initial census of the submillimeter structures that will be observed by Herschel, several of which are known Infrared Dark Clouds. Our spectral energy distributions of the main clumps in the field, located at ~7 kpc, reveal an active population with temperatures of T ~ 35–40 K and masses of ~10^3 M_⊙ for a dust emissivity index β = 1.5. The clump evolutionary stages range from evolved sources, with extended H_II regions and prominent IR stellar population, to massive young stellar objects, prior to the formation of an UCH_(II)R. The CORNISH data have revealed the details of the stellar content and structure of the UCH_(II)Rs. In most cases, the ionizing stars corresponding to the brightest radio detections are capable of accounting for the clump bolometric luminosity, in most cases powered by embedded OB stellar clusters

The BLAST View of the Star Forming Region in Aquila (ell=45deg,b=0deg)

We have carried out the first general submillimeter analysis of the field towards GRSMC 45.46+0.05, a massive star forming region in Aquila. The deconvolved 6 deg^2 (3\degree X 2\degree) maps provided by BLAST in 2005 at 250, 350, and 500 micron were used to perform a preliminary characterization of the clump population previously investigated in the infrared, radio, and molecular maps. Interferometric CORNISH data at 4.8 GHz have also been used to characterize the Ultracompact HII regions (UCHIIRs) within the main clumps. By means of the BLAST maps we have produced an initial census of the submillimeter structures that will be observed by Herschel, several of which are known Infrared Dark Clouds (IRDCs). Our spectral energy distributions of the main clumps in the field, located at ~7 kpc, reveal an active population with temperatures of T~35-40 K and masses of ~10^3 Msun for a dust emissivity index beta=1.5. The clump evolutionary stages range from evolved sources, with extended HII regions and prominent IR stellar population, to massive young stellar objects, prior to the formation of an UCHIIR.The CORNISH data have revealed the details of the stellar content and structure of the UCHIIRs. In most cases, the ionizing stars corresponding to the brightest radio detections are capable of accounting for the clump bolometric luminosity, in most cases powered by embedded OB stellar clusters

PLANCK COLD CLUMPS IN THE lambda ORIONIS COMPLEX. I. DISCOVERY OF AN EXTREMELY YOUNG CLASS 0 PROTOSTELLAR OBJECT AND A PROTO-BROWN DWARF CANDIDATE IN THE BRIGHT-RIMMED CLUMP PGCC G192.32-11.88

We are performing a series of observations with ground-based telescopes toward Planck Galactic cold clumps (PGCCs) in the lambda Orionis complex in order to systematically investigate the effects of stellar feedback. In the particular case of PGCC G192.32-11.88, we discovered an extremely young Class 0 protostellar object (G192N) and a proto-brown dwarf candidate (G192S). G192N and G192S are located in a gravitationally bound brightrimmed clump. The velocity and temperature gradients seen in line emission of CO isotopologues indicate that PGCC G192.32-11.88 is externally heated and compressed. G192N probably has the lowest bolometric luminosity (similar to 0.8 L-circle dot) and accretion rate (6.3 x 10(-7) M-circle dot yr(-1)) when compared with other young Class 0 sources (e.g., PACS Bright Red Sources) in the Orion complex. It has slightly larger internal luminosity (0.21 +/- 0.01 L-circle dot) and outflow velocity (similar to 14 km s(-1)) than the predictions of first hydrostatic cores (FHSCs). G192N might be among the youngest Class 0 sources, which are slightly more evolved than an FHSC. Considering its low internal luminosity (0.08 +/- 0.01 L-circle dot) and accretion rate (2.8 x 10(-8) M-circle dot yr(-1)), G192S is an ideal proto-brown dwarf candidate. The star formation efficiency (similar to 0.3%-0.4%) and core formation efficiency (similar to 1%) in PGCC G192.32-11.88 are significantly smaller than in other giant molecular clouds or filaments, indicating that the star formation therein is greatly suppressed owing to stellar feedback.Peer reviewe

Understanding the Earliest Stages of High-mass Star Formation

High-mass star formation, contrary to its low-mass counterpart, remains poorly understood. This project aims to constrain the mechanisms driving the formation of OB stars and their precursors with the analysis of two main fields: Aquila, observed by the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST), and the W3 Giant Molecular Cloud (GMC), provided by the Herschel Space Observatory and for which Canada has lead responsibility within the Herschel programme. The Aquila analysis, combining BLAST and interferometry data, presents a full characterization of the main high-mass star forming clumps in this field and their Ultracompact HII regions. We have found highly clustered environments, a range of evolutionary stages, and signatures of triggering within the parsec-scale clumps hosting OB stars. Our study of the W3 GMC comprises an analysis of the young stellar objects (YSO), the regions currently hosting on-going high-mass star formation, the environment, history, and compact source population. Spitzer data were used to identify, classify, and investigate the clustering properties of the YSO population. These complemented the Herschel datasets, with which we have produced column density and temperature maps, a full analysis of the probability density functions and mass distributions, and a catalog of reliable sources at ~ 36'' resolution. The clump sample was characterized and classified according to their stellar content, spectral energy distributions, the NH2/T maps, the L/M diagram, and various schemes presented in previous studies. Based on our environmental analysis and the unique intrinsic and stellar properties of the clumps hosting the clusters of high-mass stars in W3, we have proposed a new high-mass/cluster formation scenario based on external feedback from high-mass stars. This ‘convergent constructive feedback’ mechanism could not only explain the formation of clusters with an observed decreasing age (and increasing system/source mass) toward the innermost regions, but could also ensure the availability of material during cluster formation, explain the formation of rare Trapezium-like systems, and address various outstanding issues in high-mass star formation theory. New simulations and additional observations are now required in order to constrain the details and implications of this model.Ph

From Clouds to Young Stellar Objects and back again: the all-in-one view from the Herschel infrared Galactic Plane Survey

From diffuse interstellar cirrus to dense atomic and molecular clouds, from protostellar to post-AGB envelopes, from super-shells to supernovae remnants, the Herschel Hi-GAL survey offer an unprecedented snapshot of all the different phases of the Galactic ISM, its evolution and interactions. I will present early results on a variety of topics including the lifetime of massive pre-stellar phases, the fragmentation and collapse of extended structures, the timeline for massive star formation, dust properties in cirrus and molecular clouds