We present the first detection and mapping of the HD 32297 debris disk at 1.3 mm with the Combined ARray for Millimeter Astronomy (CARMA). With a sub-arcsecond beam, this detection represents the highest angular resolution (sub)mm debris... more
We present the first detection and mapping of the HD 32297 debris disk at 1.3 mm with the Combined ARray for Millimeter Astronomy (CARMA). With a sub-arcsecond beam, this detection represents the highest angular resolution (sub)mm debris disk observation made to date. Our model fits to the spectral energy distribution from the CARMA flux and new Spitzer MIPS photometry support the earlier suggestion that at least two, possibly three, distinct grain populations are traced by the current data. The observed millimeter map shows an asymmetry between the northeast and southwest disk lobes, suggesting large grains may be trapped in resonance with an unseen exoplanet. Alternatively, the observed morphology could result from the recent breakup of a massive planetesimal. A similar-scale asymmetry is also observed in scattered light but not in the mid-infrared. This contrast between asymmetry at short and long wavelengths and symmetry at intermediate wavelengths is in qualitative agreement wi...
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We present a new method to use polarimetric measurements to estimate the relative orientations of the star+disk system in each component of Pre Main Sequence (PMS) T Tauri binary stars. The principles of the method are presented, together... more
We present a new method to use polarimetric measurements to estimate the relative orientations of the star+disk system in each component of Pre Main Sequence (PMS) T Tauri binary stars. The principles of the method are presented, together with a review of polarimetric data available in the literature on wide systems (8-40arcsec ) in Taurus. We show that this method
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We propose to use NIRI to measure the depth and shape of the 3(micron) water ice absorption feature in three edge-on disks in the Ophiuchus molecular cloud. This will provide us with an estimate of the total column density of ice in these... more
We propose to use NIRI to measure the depth and shape of the 3(micron) water ice absorption feature in three edge-on disks in the Ophiuchus molecular cloud. This will provide us with an estimate of the total column density of ice in these disks and an indication of the thermal processing it has experienced. In protoplanetary disks, water ice coats
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We will present an overview of the main features of the current and next (to be released at the end of the summer) versions of the ASPRO software that are being developed by the JMMC to prepare VLTI observing programs. To help ASPRO users... more
We will present an overview of the main features of the current and next (to be released at the end of the summer) versions of the ASPRO software that are being developed by the JMMC to prepare VLTI observing programs. To help ASPRO users prepare their AMBER and MIDI proposals, an active helpdesk will also be available.
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Using photometry at just two wavelengths it is possible to fit a blackbody to the spectrum of infrared excess that is the signature of a debris disc. From this the location of the dust can be inferred. However, it is well known that dust... more
Using photometry at just two wavelengths it is possible to fit a blackbody to the spectrum of infrared excess that is the signature of a debris disc. From this the location of the dust can be inferred. However, it is well known that dust in debris discs is not a perfect blackbody. By resolving debris discs we can find the actual location of the dust and compare this to that inferred from the blackbody fit. Using the Herschel Space Observatory we resolved many systems as part of the DEBRIS survey. Here we discuss a sample of 9 discs surrounding A stars and find that the discs are actually located between 1 and 2.5 times further from their star than predicted by blackbody fits to the spectral energy distribution (SED). The variation in this ratio is due to differences in stellar luminosities, location of the dust, size distribution and composition of the dust.
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We present new high-resolution observations and modeling of SSTtau J042021+ 281349, a 400 AU-radius edge-on protoplanetary disk. We have gathered visible and near-infrared scattered light images of the system with the Hubble Space... more
We present new high-resolution observations and modeling of SSTtau J042021+ 281349, a 400 AU-radius edge-on protoplanetary disk. We have gathered visible and near-infrared scattered light images of the system with the Hubble Space Telescope and Keck adaptive optics system, as well as a 1.3 mm continuum map with CARMA. Compared to the well-known HH 30 disk, this new system is remarkable because of its spectacular bipolar jet and the high degree of lateral symmetry of the disk. Indeed, we argue that this system is a “cleaner” prototype for edge-on disks. In addition, the apparent achromaticity of dust properties (most notably the almost grey opacity law) from the visible to the near-infrared in this disk suggests that it is in an advanced stage of dust evolution.
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Although planets are being discovered around stars more massive than the Sun, information about the proto-planetary disks where such planets have built up is sparse. We have imaged mid-infrared emission from polycyclic aromatic... more
Although planets are being discovered around stars more massive than the Sun, information about the proto-planetary disks where such planets have built up is sparse. We have imaged mid-infrared emission from polycyclic aromatic hydrocarbons at the surface of the disk surrounding the young intermediate-mass star HD 97048 and characterized the disk. The disk is in an early stage of evolution, as indicated by its large content of dust and its hydrostatic flared geometry, indicative of the presence of a large amount of gas that is well mixed with dust and gravitationally stable. The disk is a precursor of debris disks found around more-evolved A stars such as β-Pictoris and provides the rare opportunity to witness the conditions prevailing before (or during) planet formation.
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We present a new 3D continuum radiative transfer code, MCFOST, based on a Monte-Carlo method. The reliability and efficiency of the code is tested by comparison with five different radiative transfer codes previously tested by Pascucci et... more
We present a new 3D continuum radiative transfer code, MCFOST, based on a Monte-Carlo method. The reliability and efficiency of the code is tested by comparison with five different radiative transfer codes previously tested by Pascucci et al., 2004, using a 2D disk configuration. When tested against the same disk configuration, no significant difference is found between the temperature and SED calculated with MCFOST and with the other codes. The computed values are well within the range of values computed by the other codes. The code-to-code differences are small, they rarely exceed 10% and are usually much smaller.
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We re-examine the alignment of disks and jets with the magnetic field in star forming region. Previous studies demonstrated that the jet axis of active YSOs is usually aligned with the local magnetic field. In these studies the disk was... more
We re-examine the alignment of disks and jets with the magnetic field in star forming region. Previous studies demonstrated that the jet axis of active YSOs is usually aligned with the local magnetic field. In these studies the disk was not seen and its orientation was only inferred to be perpendicular to the magnetic field. We re-examine this issue in view of the numerous high angular resolution images now available from HST Adaptive Optics and millimeter interferometry. These images give us the orientation (PA) of the systems unambiguously. We confirm that active systems with jets and outflows both embedded (class I) and active T Tauri's (class II) have their jet axis parallel and their disk perpendicular to the local magnetic field. Surprisingly however we also show that classical T Tauri stars with resolved disks but without signs of jet or outflow have a strong tendency to align differently. Their disks tend to align parallel to the magnetic field instead of perpendicular ...
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Stellar multiplicity is a ubiquitous outcome of the star-formation process. The frequency and main characteristics of multiple systems, and their dependence on primary mass and environment, are powerful tools to probe this process.... more
Stellar multiplicity is a ubiquitous outcome of the star-formation process. The frequency and main characteristics of multiple systems, and their dependence on primary mass and environment, are powerful tools to probe this process. Although early attempts were fraught with selection biases and limited completeness, instrumentation breakthroughs in the past two decades now enable robust statistical analyses. In this review, we summarize current empirical knowledge of stellar multiplicity for main sequence stars and brown dwarfs, as well as among populations of pre-main-sequence stars and embedded protostars. Among field objects, the multiplicity rate and breadth of the orbital period distribution are steep functions of the primary mass, whereas the mass ratio distribution is essentially flat for most populations other than the lowest mass objects. The time-variation of the frequency of visual companions follows two parallel, constant tracks corresponding to loose and dense stellar po...
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Abstract. We present low-resolution optical spectra of each component of 10 TTauri (TT) binary systems with separations ranging from 0.′′9 to 3.′′5 and located in the Taurus star-forming region. We derive the spectral type and Hα... more
Abstract. We present low-resolution optical spectra of each component of 10 TTauri (TT) binary systems with separations ranging from 0.′′9 to 3.′′5 and located in the Taurus star-forming region. We derive the spectral type and Hα equivalent width of each component. ...
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In this paper we present a model of the β Leo debris disc, with an emphasis on modelling the resolved Photodetector Array Camera and Spectrometer (PACS) images obtained as a part of the Herschel key programme DEBRIS. We also present new... more
In this paper we present a model of the β Leo debris disc, with an emphasis on modelling the resolved Photodetector Array Camera and Spectrometer (PACS) images obtained as a part of the Herschel key programme DEBRIS. We also present new Spectral and Photometric Imaging REceiver (SPIRE) images of the disc at 250 μm, as well as new constraints on the disc from SCUBA-2, mid-infrared (mid-IR) and scattered light imaging. Combining all the available observational constraints, we find three possible models for the β Leo (HD 102647) debris disc: (i) a two-component model, comprised of a hot component at 2 au and a cold component from 15 to 70 au; (ii) a three-component model with hot dust at 2 au, warm dust at 9 au and a cold component from 30 to 70 au, is equally valid since the cold emission is not resolved within 30 au; (iii) a somewhat less likely possibility is that the system consists of a single very eccentric planetesimal population, with pericentres at 2 au and apocentres at 65 au...
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Aims. We present a panchromatic study, involving a multiple technique approach, of the circumstellar disc surrounding the T Tauri star IM Lupi (Sz 82). Methods. We have undertaken a comprehensive observational study of IM Lupi using... more
Aims. We present a panchromatic study, involving a multiple technique approach, of the circumstellar disc surrounding the T Tauri star IM Lupi (Sz 82). Methods. We have undertaken a comprehensive observational study of IM Lupi using photometry, spectroscopy, millimetre interferometry and multi-wavelength imaging. For the first time, the disc is resolved from optical and near-infrared wavelengths in scattered light, to the millimetre regime in thermal emission.
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A concept to achieve high dynamic range images from the ground is presented. The main idea is to calibrate turbulent fluctuations of wavefronts in a telescope pupil with a fibered fully redundant aperture mask. This is the principle of... more
A concept to achieve high dynamic range images from the ground is presented. The main idea is to calibrate turbulent fluctuations of wavefronts in a telescope pupil with a fibered fully redundant aperture mask. This is the principle of the FIRST instrument whose first prototype version is to see stellar photons in July 2010 at Lick Observatory. Lab results and
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ABSTRACT We present NICMOS and ACS Hubble Space Telescope coronagraphic imaging observations of the AU Mic debris disk. The disk is resolved from about 9 AU to 200 AU from the star. Preliminary results indicate that the outer disk (beyond... more
ABSTRACT We present NICMOS and ACS Hubble Space Telescope coronagraphic imaging observations of the AU Mic debris disk. The disk is resolved from about 9 AU to 200 AU from the star. Preliminary results indicate that the outer disk (beyond 75AU) exhibits a warp, similar to that observed in the Beta Pictoris disk. The sensitivity, wavelength coverage, and PSF stability afforded by our observations provide an accurate measurement of the color gradient of the disk. The optical to near-infrared colors indicate that as the projected distance from the star increases, the dust grains preferentially scatter increasingly bluer light. We compare the observed midplane surface brightness, color, and polarization profiles to models previously suggested in the literature. Results to date indicate that the dynamical models of Strubbe & Chiang (2006) are in qualitative agreement with the observations, assuming reasonable properties for the dust grain composition and porosity. This work was also supported in part by the University of California Lab Research Program 09-LR-01-118057-GRAJ and NSF AST-0909188. Support for GO-10228 was provided by NASA through a grant from STScI under NASA contract NAS5-26555.