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تسجيل مستخدم جديدThe circumestellar disk of the B0 protostar powering the HH 80-81 radio jet
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We present subarcsecond angular resolution observations carried out with the Submillimeter Array (SMA) at 880 $mu$m centered at the B0-type protostar GGD27~MM1, the driving source of the parsec scale HH 80-81 jet. We constrain its polarized continuum emission to be $lesssim0.8%$ at this wavelength. Its submm spectrum is dominated by sulfur-bearing species tracing a rotating disk--like structure (SO and SO$_2$ isotopologues mainly), but also shows HCN-bearing and CH$_3$OH lines, which trace the disk and the outflow cavity walls excavated by the HH 80-81 jet. The presence of many sulfurated lines could indicate the presence of shocked gas at the disks centrifugal barrier or that MM1 is a hot core at an evolved stage. The resolved SO$_2$ emission traces very well the disk kinematics and we fit the SMA observations using a thin-disk Keplerian model, which gives the inclination (47$^{circ}$), the inner ($lesssim170$ AU) and outer ($sim950-1300$~AU) radii and the disks rotation velocity (3.4 km s$^{-1}$ at a putative radius of 1700 AU). We roughly estimate a protostellar dynamical mass of 4-18msun. MM2 and WMC cores show, comparatively, an almost empty spectra suggesting that they are associated with extended emission detected in previous low-angular resolution observations, and therefore indicating youth (MM2) or the presence of a less massive object (WMC).
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