James Di Francesco
A5063062592- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Molecular Spectroscopy and Structure
- Atmospheric Ozone and Climate
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Advanced Combustion Engine Technologies
- Astrophysical Phenomena and Observations
- Spectroscopy and Laser Applications
- Radio Astronomy Observations and Technology
- Superconducting and THz Device Technology
- Atomic and Molecular Physics
- Space Exploration and Technology
- Astronomical Observations and Instrumentation
- Spacecraft and Cryogenic Technologies
- Solar and Space Plasma Dynamics
- Advanced Chemical Physics Studies
- Calibration and Measurement Techniques
- Gamma-ray bursts and supernovae
- History and Developments in Astronomy
- Astrophysics and Cosmic Phenomena
- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Isotope Analysis in Ecology
Herzberg Institute of Astrophysics
2016-2025
University of Victoria
2016-2025
National Research Council Canada
2012-2021
National Institute for Astrophysics
2019
Victoria Heart Institute Foundation
2015
National Academies of Sciences, Engineering, and Medicine
2012-2014
University of Calgary
2006-2009
University of California, Berkeley
2000-2004
Center for Astrophysics Harvard & Smithsonian
1998-2003
Berkeley College
2002
We summarize the first results from Gould Belt survey, obtained toward Aquila Rift and Polaris Flare regions during 'science demonstration phase' of Herschel. Our 70-500 micron images taken in parallel mode with SPIRE PACS cameras reveal a wealth filamentary structure, as well numerous dense cores embedded filaments. Between ~ 350 500 prestellar 45-60 Class 0 protostars can be identified field, while unbound starless no are observed field. The core mass function (CMF) derived for region...
We provide a first look at the results of Herschel Gould Belt survey toward IC5146 molecular cloud and present preliminary analysis filamentary structure in this region. The column density map, derived from our 70-500 micron data, reveals complex network filaments, confirms that these filaments are main birth sites prestellar cores. analyze profiles 27 show underlying radial fall off as r^{-1.5} to r^{-2.5} large radii. Our result is seem be characterized by narrow distribution widths having...
Hi-GAL, the Herschel infrared Galactic Plane Survey, is an Open Time Key Project of Space Observatory. It will make unbiased photometric survey inner plane by mapping a 2° wide strip in longitude range ∣l∣ < 60° five wavebands between 70 μm and 500 μm. The aim Hi-GAL to detect earliest phases formation molecular clouds high-mass stars use optimum combination wavelength coverage, sensitivity, strategy, speed deliver homogeneous census star-forming regions cold structures interstellar medium....
We present first results from the Herschel Gould Belt survey for B211/L1495 region in Taurus molecular cloud. Thanks to their high sensitivity and dynamic range, images reveal structure of dense, star-forming filament B211 with unprecedented detail, along presence striations perpendicular generally oriented magnetic field direction as traced by optical polarization vectors. Based on column density dust temperature maps derived data, we find that radial profile approaches a power-law behavior...
We present the SCUBA Legacy Catalogues, two comprehensive sets of continuum maps (and catalogues) using data at 850 microns and 450 various astronomical objects obtained with Submillimetre Common User Bolometer Array (SCUBA). The Fundamental Map Dataset contains only where superior atmospheric opacity calibration were available. Extended is comprised regardless quality calibration. Each 1.2 degree x locations existed in JCMT archive, imaged matrix inversion method. 1423 1357 microns. 1547...
For many years feedback processes generated by OB-stars in molecular clouds, including expanding ionization fronts, stellar winds, or UV-radiation, have been proposed to trigger subsequent star formation. However, hydrodynamic models radiation and gravity show that UV-illumination has little no impact on the global dynamical evolution of cloud. The Rosette cloud, irradiated NGC2244 cluster, is a template region for triggered star-formation, we investigated its spatial density structure...
We present the full catalog of Young Stellar Objects (YSOs) identified in 18 molecular clouds surveyed by Spitzer Space Telescope "cores to disks" (c2d) and "Gould Belt" (GB) Legacy surveys. Using standard techniques developed c2d project, we identify 3239 candidate YSOs clouds, 2966 which survive visual inspection form our final Gould Belt. compile extinction corrected SEDs for all calculate tabulate infrared spectral index, bolometric luminosity, temperature each object. find that 326...
The origin and possible universality of the stellar initial mass function (IMF) is a major issue in astrophysics. One main objectives Herschel Gould Belt Survey to clarify link between prestellar core (CMF) IMF. We present discuss derived from data for large population cores discovered with SPIRE PACS Aquila Rift cloud complex at d ~ 260 pc. detect total 541 starless entire ~11 deg^2 area field imaged 70-500 micron SPIRE/PACS. Most these appear be gravitationally bound, thus nature. Our...
A key parameter to the description of all star formation processes is density structure gas. In this Letter, we make use probability distribution functions (PDFs) Herschel column maps Orion B, Aquila, and Polaris, obtained with Gould Belt survey (HGBS). We aim understand which physical influence PDF shape, signatures. The PDFs B (Aquila) show a lognormal for low densities until AV ∼ 3 (6), power-law tail high densities, consistent ρ∝r−2 profile equivalent spherical distribution. broadened by...
[Abridged] Molecular filaments have received special attention recently, thanks to new observational results on their properties. In particular, our early analysis of filament properties revealed a narrow distribution median widths centered at value about 0.1 pc. Here, we extend and complement initial study with the filamentary structures observed in eight nearby molecular clouds. We use column density maps derived from Herschel data DisPerSE algorithm trace network each cloud. build...
This paper presents a large spectral line and continuum survey of 8 deeply embedded, low-mass protostellar cores using the Submillimeter Array. Each source was observed in high excitation lines some most common molecular species, CO, HCO+, CS, SO, H2CO, CH3OH SiO. Line emission from 11 species originating warm dense gas have been imaged at angular resolution (1-3"; typically 200-600 AU) together with 230 GHz (1.3 mm) 345 (0.8 mm). Compact is for all sources which likely originates marginally...
Our PACS and SPIRE images of the Aquila Rift part Polaris Flare regions, taken during science demonstration phase <i>Herschel<i/> discovered fascinating, omnipresent filamentary structures that appear to be physically related compact cores. We briefly describe a new multi-scale, multi-wavelength source extraction method used detect objects measure their parameters in our images. All extracted starless cores (541 302 Polaris) form long very narrow filaments. With its combination far-IR...
We present the initial highlights of HOBYS key program, which are based on <i>Herschel<i/> images Rosette molecular complex and maps RCW120 H ii region. Using both SPIRE at 250/350/500 <i>μ<i/>m PACS 70/160 or 100/160 <i>μ<i/>m, survey provides an unbiased complete census intermediate- to high-mass young stellar objects, some not detected by <i>Spitzer<i/>. Key core properties, such as bolometric luminosity mass (as derived from spectral energy distributions), used constrain their...
We present an overview of data available for the Ophiuchus and Perseus molecular clouds from Phase I COMPLETE Survey Star-Forming Regions. This survey provides a range complementary to Spitzer Legacy Program "From Molecular Cores Planet Forming Disks." includes following: extinction maps derived Two Micron All Sky (2MASS) near-infrared using NICER algorithm; temperature IRAS 60 100 μm emission; H atomic gas; 12CO 13CO submillimeter continuum images emission dust in dense cores. Not...
We present an analysis of ~3.5 deg2 submillimeter continuum and extinction data the Perseus molecular cloud. identify 58 clumps in map, we 39 structures ("cores") 11 associations ("super cores") map. The cumulative mass distributions cores have steep slopes (α ~ 2 1.5-2, respectively), steeper than Salpeter initial function (IMF; α = 1.35), while distribution super has a shallow slope 1). Most are well fit by stable Bonnor-Ebert spheres with 10 K < T 19 5.5 <(Pext/k) 6.0. found only highest...
This paper describes a James Clerk Maxwell Telescope (JCMT) legacy survey that has been awarded roughly 500 hr of observing time to be carried out from 2007 2009. In this survey, we will map with SCUBA‐2 (Submillimetre Common‐User Bolometer Array 2) almost all the well‐known low‐mass and intermediate‐mass star‐forming regions within 0.5 kpc are accessible JCMT. Most these locations associated Gould Belt. From observations, produce flux‐limited snapshot star formation near Sun, providing...
We present an overview of the first data release (DR1) and first-look science from Green Bank Ammonia Survey (GAS). GAS is a Large Program at Telescope to map all Gould Belt star-forming regions with $A_V \gtrsim 7$ mag visible northern hemisphere in emission NH$_3$ other key molecular tracers. This includes for four clouds: B18 Taurus, NGC 1333 Perseus, L1688 Ophiuchus, Orion A North Orion. compare dust continuum Herschel, find that two tracers correspond closely. over 60\% lines-of-sight...
In order to characterise the cloud structures responsible for formation of high-mass stars, we present Herschel observations DR21 environment. Maps column density and dust temperature unveil structure ridge several connected filaments. The has densities higher than 1023 cm-2 over a region 2.3 pc2. It shows substructured profiles branches into two major filaments in north. masses range between 130 1400 M⊙, whereas mass is 15 000 M⊙. accretion these onto ridge, suggested by previous molecular...
In this paper, we present the first observations of Ophiuchus molecular cloud performed as part James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) with SCUBA-2 instrument.We demonstrate methods for combining these data previous HARP CO, Herschel, and IRAM N 2 H + in order to accurately quantify properties sources Ophiuchus.We produce a catalogue all found by SCUBA-2.We separate into protostars starless cores.We list cores perform full virial analysis, including external...
A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions tens milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up ~15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from September late November 2014, culminating in end-to-end observations, calibrations, imaging selected Science Verification (SV) targets. This paper presents an overview campaign its main results,...
We determine the magnetic field strength in OMC 1 region of Orion A filament via a new implementation Chandrasekhar-Fermi method using observations performed as part James Clerk Maxwell Telescope (JCMT) B-Fields In Star-Forming Region Observations (BISTRO) survey with POL-2 instrument. combine BISTRO data archival SCUBA-2 and HARP to find plane-of-sky $B_{\rm pos}=6.6\pm4.7$ mG, where $\delta B_{\rm pos}=4.7$ mG represents predominantly systematic uncertainty. develop for measuring angular...
Debris discs are evidence of the ongoing destructive collisions between planetesimals, and their presence around stars also suggests that planets exist in these systems. In this paper, we present submillimetre images thermal emission from debris formed SCUBA-2 Observations Nearby Stars (SONS) survey, one seven legacy surveys undertaken on James Clerk Maxwell Telescope 2012 2015. The overall results survey presented form 850 μm (and 450 μm, where possible) fluxes for observed fields. Excess...
We present ALMA 850 $\mu$m continuum observations of the Orion Nebula Cluster that provide highest angular resolution ($\sim 0\rlap{.}''1 \approx 40$ AU) and deepest sensitivity 0.1$ mJy) region to date. mosaicked a field containing $\sim 225$ optical or near-IR-identified young stars, 60$ which are also optically-identified "proplyds". detect emission at towards 80$% proplyd sample, 50$% larger sample previously-identified cluster members. Detected objects have fluxes 0.5$-80 mJy. remove...
We present a catalogue of dense cores in ∼4° × 2° field the Taurus star-forming region, inclusive L1495 cloud, derived from Herschel SPIRE and PACS observations 70 μm, 160 250 350 500 μm continuum bands. Estimates mean dust temperature total mass are using modified blackbody fits to spectral energy distributions. detect 525 starless which ∼10–20 per cent gravitationally bound therefore presumably prestellar. Our census unbound objects is ∼85 complete for M > 0.015 M⊙ low-density regions (AV...