Probing the gaseous disk of T Tau N with CN 5-4 lines
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We present spectrally resolved observations of the young multiple system T Tau in atomic and molecular lines obtained with the Heterodyne Instrument for the Far Infrared on board Herschel. While CO, H2O, [C II], and SO lines trace the envelope and the outflowing gas up to velocities of 33 km s-1 with respect to systemic, the CN 5-4 hyperfine structure lines at 566.7, 566.9 GHz show a narrow double-peaked profile centered at systemic velocity, consistent with an origin in the outer region of the compact disk of T Tau N. Disk modeling of the T Tau N disk with the thermo-chemical code ProDiMo produces CN line fluxes and profiles consistent with the observed ones and constrain the size of the gaseous disk (Rout 110+10-20 AU) and its inclination (i = 25°± 5°). The model indicates that the CN lines originate in a disk upper layer at 40-110 AU from the star, which is irradiated by the stellar UV field and heated up to temperatures of 50-700 K. With respect to previously observed CN 2-1 millimeter lines, the CN 5-4 lines appear to be less affected by envelope emission, due to their larger critical density and excitation temperature. Hence, high-J CN lines are a unique confusion-free tracer of embedded disks, such as the disk of T Tau N.
Podio , L , Kamp , I , Codella , C , Nisini , B , Aresu , G , Brittain , S , Cabrit , S , Dougados , C , Grady , C , Meijerink , R , Sandell , G , Spaans , M , Thi , W-F , White , G J & Woitke , P 2014 , ' Probing the gaseous disk of T Tau N with CN 5-4 lines ' Astrophysical Journal Letters , vol 783 , no. 2 , L26 . DOI: 10.1088/2041-8205/783/2/L26
Astrophysical Journal Letters
© 2014. The American Astronomical Society. All rights reserved.
L.P. and S.D.B. acknowledge funding from the European FP7 (PIEF-GA-2009-253896) and the National Science Foundation (AST-0954811).
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