Oral Presentation
High resolution ALMA observation of the CO(3-2) and 350 GHz continuum emissions of the debris disc of 49 Ceti
Presenter: Nhung Pham (Vietnam National Satellite Centre /VAST)
We present high resolution ALMA observations of the CO(3-2) and 350 GHz continuum emissions of the debris disc of 49 Ceti, known to be particularly rich in molecular gas in spite of its age. The main new results are: i) both CO and dust discs share a same position angle and a same inclination but the gas disc is more homogeneous, more central and thinner than the dust disc; ii) evidence is obtained for a significant deficit of observed CO(3-2) emission at Doppler velocities differing from the star systemic velocity by less than 1 \kms; iii) the source brightness is measured to correspond to a CO mass of $\sim$3$\times$10$^{-4}$ Earth masses and the continuum flux density is in good agreement with current SED estimates; iv) gas velocities are accurately measured and found Keplerian over a broad range of disc radii; v) the observed CO(3-2) line width is dominated by Keplerian shear and upper limits are obtained to the intrinsic line width. Simple phenomenological models of both CO(3-2) and \mbox{350 GHz} continuum emissions are presented, requiring the use of only very few parameters. The results are discussed in the frame of currently favoured models.
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