Simon Casassus

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We report on advances in the study of the cores of NGC 6302 and NGC 6537 using infrared grating and echelle spectroscopy. In NGC 6302, emission lines from species spanning a large range of ionization potential, and in particular [Si ix] 3.934 μm, are interpreted using photoionization models (including CLOUDY), which allow us to reestimate the central star’s(More)
The formation of gaseous giant planets is thought to occur in the first few million years after stellar birth. Models predict that the process produces a deep gap in the dust component (shallower in the gas). Infrared observations of the disk around the young star HD 142527 (at a distance of about 140 parsecs from Earth) found an inner disk about 10(More)
Polarization observations of the cosmic microwave background with the Cosmic Background Imager from September 2002 to May 2004 provide a significant detection of the E-mode polarization and reveal an angular power spectrum of polarized emission showing peaks and valleys that are shifted in phase by half a cycle relative to those of the total intensity(More)
Context. HD 142527 is a pre-transition disk with strong evidence for on-going planet formation. Recent observations show a disrupted disk with spiral arms, a dust-depleted inner cavity and the possible presence of gas streams driving gas from the outer disk towards the central star. Aims. We aim to derive the morphology of the disk, as well as the(More)
[LPH96] 201.663 1.643, a diffuse H ii region, has been reported to be a candidate for emission from rapidly spinning dust grains. We present Cosmic Background Imager (CBI) observations at 26–36 GHz that show no evidence for significant anomalous emission. The spectral index within the CBI band, and between CBI and Effelsberg data at 1.4 and 2.7 GHz, is(More)
We present observations of the Vela X region at 31 GHz using the Cosmic Background Imager (CBI). We find a strong compact radio source (5A9 ; 4A1, FWHM) about the Vela pulsar, which we associate with the Vela pulsar wind nebula (PWN) recently discovered at lower radio frequencies. The CBI’s 40 resolution for a 450 field of view allows the PWN to be studied(More)
Many stars are surrounded by disks of dusty debris formed in the collisions of asteroids, comets, and dwarf planets, but is gas also released in such events? Observations at submillimeter wavelengths of the archetypal debris disk around β Pictoris show that 0.3% of a Moon mass of carbon monoxide orbits in its debris belt. The gas distribution is highly(More)
We present evidence for anomalous microwave emission in the RCW175 Hii region. Motivated by 33 GHz 13 resolution data from the Very Small Array (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager (CBI) at a resolution of 4. The region consists of two distinct components, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise(More)
An anomalous radio continuum component at cm-wavelengths has been observed in various sources, including dark clouds. This continuum component represents a new property of the ISM. In this work we focus on one particular dark cloud, the bright reflection nebula M 78. The main goal of this work is to investigate the cm-wave continuum emission in a prominent(More)
Lynds dark cloud LDN1622 represents one of the best examples of anomalous dust emission, possibly originating from small spinning dust grains. We present Cosmic Background Imager (CBI) 31-GHz data of LDN1621, a diffuse dark cloud to the north of LDN1622 in a region known as Orion East. A broken ring-like structure with diameter ≈20 arcmin of diffuse(More)