tokens: compensate for attenuation; a narrower attenuation region would imply a less steep radial dependence of the CO(3–2) effective emissivity. (vi) Values of the intensities integrated over the source size but not corrected for the loss of short spacing have been given for both CO(3–2) emission, 7.1 ± 0.4 Jy km s −1 , and continuum emission, 11.4 ± 0.5 mJy. Crude estimates of the short-spacing correction have been given at the respective levels of 1.6 Jy km s −1 and 5 mJy. The gas value is in good agreement with the value measured earlier by Dent et al. ( 2005 ) but the dust value is larger than that measured by Song et al. ( 2004 ) and close to the predictions of the disc models proposed by Hughes et al. ( 2008 ) and Roberge et al. ( 2013 ), according to which the CO mass of the disc is between ∼2 × 10 −4 and ∼10 −3 Earth masses and the 0.86 mm SED value is ∼19 mJy. The crudeness of our estimated short-spacing correction prevents a reliable resolution of this apparent disagreement, which will require new lower resolution observations. The use in this work of an effective emissivity to model the detected emission mixes the effects of temperature and density and the new results do not justify repeating the detailed analysis that Hughes et al. ( 2008 ) and Roberge et al. ( 2013 ) have made of the disc structure and chemistry for both gas and dust. (vii) Kinematics has been found to be Keplerian over a very broad range of distances from the star, typically 20–200 au, with a power index of and a rotation velocity of 5.1 ± 0.1 km s −1 at a distance of 60 au (1 arcsec) from the star, corresponding to a mass of 1.73 ± 0.10 solar masses for the central star. The observed line width was observed to be dominated by Keplerian shear over most of the disc volume and upper limits to the intrinsic line width (FWHM) have been evaluated, decreasing from 1.4 ± 0.3 km s −1 for | x | 1 arcsec to 0.8 ± 0.1 km s −1 for 2 | x | 3 arcsec. 6.2 Implications on the disc structure and chemistry (Hughes et al. <xref ref-type="bibr" rid="bib9">2008</xref>) The very detailed analysis of the chemistry that governs the morphology and temperature of the disc that was made by Hughes et al. ( 2008 ) remains essentially valid. However, some of the assumptions made by these authors need now to be modified; the inclination angle with respect to the line of sight is definitely non-zero; the dust extends to significantly larger distances from the star than the gas does, both radially and axially; the inner radius of the gas disc is nearly equal to the gravitational radius, ∼20 au, rather than twice this value; the lumpiness of the dust disc contrasts with the smoothness of the gas disc; the apparent warping of the gas disc suggested by the SMA data is not confirmed by the ALMA data; the central attenuation, for which the ALMA data gives strong evidence, can no longer be ignored. Yet, the analysis made by Hughes et al. ( 2008 ) of the factors governing the physics and chemistry of the gas
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