GOPAL NARAYANAN's Past Observational Projects

• Detection of Unique Signature of Infall: As part of my dissertation, I undertook a search for the ``blue-bulge'' infall signature (see Walker, Narayanan and Boss 1994) towards a selection of protostellar objects. In CSO and JCMT runs, we detected this unique new infall signature in IRAS 16293 (Narayanan, Walker, and Buckley, 1998). With the help of spectral profiles and maps derived from 3-dimensional collapse models based on the theory of Terebey, Shu and Cassen (TSC, 1984), we set constraints on the region of infall (Narayanan and Walker 1998).

• Near-IR Spectroscopy of YSOs: With George Rieke and Ana Biscaya at Steward Observatory, I observed a sample of YSOs with FSpec at the Steward 90'' telescope (Biscaya et al. 1997). We monitored the 2.3 $\mu$m $\Delta v$=2 band head emission of CO in a selected list of objects. Many of the objects showed considerable variation in both the CO bandhead flux and continuum in timescales as short as a few days.

• Cepheus A: I studied in detail the outflow system in the High Mass Starforming region of Cepheus A (Narayanan and Walker, 1996). Using CO data from the Caltech Submillimeter Observatory (CSO), we deduced that the outflow had multiple epochs of activity. We followed up with BIMA and NRAO 12m observations. The interferometric and single-dish data were combined, and well-sampled, high resolution maps were made. These maps provided further evidence for episodicity and established the morphology of the outflow. We constructed a 3-dimensional, LTE molecular outflow model and wrote a simple self-consistent LTE radiative transfer code that could analyse any geometry to produce line-profiles, integrated intensity maps and velocity moment maps. Combining the outflow and the radiative transfer code, we performed an extensive parameter study of outflow geometries with single and episodic epochs of activity.

• Detection of [CI]: I played an integral part in the first detection of [CI] in molecular outflows associated with Young Stellar Objects (Walker et al. 1993). Eleven sources were surveyed with the CSO. No evidence was found for shock enhancement of [CI] in the swept-up material. We performed mapping of the [CI] emission in the DR21 outflow.

• HH 7-11 EHV Outflow: I worked with John Carlstrom at Caltech in the observation and analysis of Owens Valley Millimeter Interferometer data from the high velocity molecular outflow in HH 7-11. We detected a binary companion in continuum, and mapped the CO outflow.