Hidden Disk Areas: HPA and DCO

Detection of DCO in a circumstellar disk

We report the first detection of DCO in a circumstellar disk. The DCO J=5–4 line at 360.169 GHz is observed with the 15m James Clerk Maxwell Telescope in the disk around the pre-main sequence star TW Hya. Together with measurements of the HCO and HCO J=4–3 lines, this allows an accurate determination of the DCO/HCO ratio in this disk. The inferred value of 0.035±0.015 is close to that found in ...

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 ≃ 4×10−3, an order of magnitude sm...

Resolving the Chemistry in the Disk of Tw Hydrae. I. Deuterated Species

We present Submillimeter Array observations of several deuterated species in the disk around the classical T Tauri star TW Hydrae at arcsecond scales, including detections of the DCN J 1⁄4 3Y2 and DCO J 1⁄4 3Y2 lines and upper limits to the HDO 31;2Y22;1, ortho-H2D 11;0Y11;1, and para-D2H 11;0Y10;1 transitions. We also present observations of the HCN J 1⁄4 3Y2, HCO J 1⁄4 3Y2, and HCO J 1⁄4 4Y3 ...

Errata for "A TDC-Free Mostly-Digital FDC-PLL Frequency Synthesizer With a 2.8-3.5 GHz DCO"

Communicating object group and protocols for distributed systems

Distributed communicating object groups, relevant algorithms and object communication protocols are presented. The distributed communicating object group system (called DCO) is built on the basis of hierarchy group communication protocols for networks. The system can be used as a speci®cation and design environment for distributed fault-tolerant object-oriented (OO) applications. By combining d...