arXiv subjects

Stéphane Guilloteau

Publications and source records attributed to Stéphane Guilloteau.

21 records · Page 2Linked to original sources

arXiv2006

Plateau de Bure Interferometer Observations of the Disk and Outflow of HH30

HH30 is a well-known Pre-Main-Sequence star in Taurus. HST observations have revealed a flared, edge-on disk driving a highly-collimated optical jet, making this object a case study for the disk-jet-outflow paradigm. We obtained high angular resolution (about 1") observations of the dust continuum at 2.7 and 1.3 mm, and of the 12CO(2-1), 13CO(2-1) & (1-0), C18O(1-0) emissions around HH30. A standard disk model is used to fit the 13CO(2-1) uv-plane visibilities and derive the disk properties, and the stellar mass. It results that HH30 is a low mass TTauri of spectral type around M1 and age 1 to 4 Myrs, surrounded by a medium size Keplerian disk, of mass around 4e-3 Msun and outer radius 420 AU. The disk rotation vector points toward the North-Eastern jet. Using a distance of 140 pc, we deduce a stellar mass of 0.45 Msun. A highly asymmetric outflow originates from the inner parts of the disk. It presents to first order a conical morphology with a 30 degree half opening angle and a constant (12 km/s) radial velocity field. Outflow rotation was searched for but not found. These observations do not enable to assign the origin of the molecular outflow to entrainment by the optical jet or to a disk wind. In the latter case, the upper limit of the outflow rotation velocity implies an origin in the inner 15 AU of the disk.

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arXiv2006

Deuterated molecules in DM Tau: DCO+, but no HDO

We report the detection of the J=2-1 line of DCO+ in the proto-planetary disk of DM Tau and re-analyze the spectrum covering the 465 GHz transition of HDO in this source, recently published by Ceccarelli et al. (2005). A modelling of the DCO+ line profile with the source parameters derived from high resolution HCO+ observations yields a DCO+/HCO+ abundance ratio of about 0.004, an order of magnitude smaller than that derived in the low mass cores. The re-analysis of the 465 GHz spectrum, using the proper continuum flux (0.5 Jy) and source systemic velocity (6.05 km/s), makes it clear that the absorption features attributed to HDO and C6H are almost certainly unrelated to these species. We show that the line-to-continuum ratio of an absorption line in front of a Keplerian disk can hardly exceed the ratio of the turbulent velocity to the projected rotation velocity at the disk edge, unless the line is optically very thick (tau > 10 000). This ratio is typically 0.1-0.3 in proto-planetary disks and is about 0.15 in DM Tau, much smaller than that for the alleged absorption features. We also show that the detection of H2D+ in DM Tau, previously reported by these authors, is only a 2-sigma detection when the proper velocity is adopted. So far, DCO+ is thus the only deuterated molecule clearly detected in proto-planetary disks.

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arXiv2005

Sub-arcsec imaging of the AB Aur molecular disk and envelope at millimeter wavelengths: a non Keplerian disk

We present sub-arcsecond images of AB Auriga obtained with the IRAM Plateau de Bure interferometer in the isotopologues of CO, and in continuum at 3 and 1.3 mm. Instead of being centrally peaked, the continuum emission is dominated by a bright, asymmetric (spiral-like) feature at about 140 AU from the central star. The large scale molecular structure suggests the AB Aur disk is inclined between 23 and 43 degrees, but the strong asymmetry of the continuum and molecular emission prevents an accurate determination of the inclination of the inner parts. We find significant non-Keplerian motion, with a best fit exponent for the rotation velocity law of 0.41 +/- 0.01, but no evidence for radial motions. The disk has an inner hole about 70 AU in radius. The disk is warm and shows no evidence of depletion of CO. The dust properties suggest the dust is less evolved than in typical T Tauri disks. Both the spiral-like feature and the departure from purely Keplerian motions indicates the AB Aur disk is not in quasi-equilibrium. Disk self-gravity is insufficient to create the perturbation. This behavior may be related either to an early phase of star formation in which the Keplerian regime is not yet fully established and/or to a disturbance of yet unknown origin. An alternate, but unproven, possibility is that of a low mass companion located about 40 AU from AB Aur.

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