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We report the first observations of T Tauri stars (T-, HL-, DG-, RY-, and GG-Tau) in the 12 CO (6-5) line. The observations trace the dynamics of warm (T≥60 K) and dense (≥10 5 cm −3 ) gas on a scale below 10″. The CO submillimeter emission probably originates in shocks where a stellar wind interacts with a high column density of molecular material close to the star. Additional 12 CO (3-2) and C 18 O (2-1) data show that the spatial distributions and line widths in T-Tau and HL-Tau are not consistent with Keplerian rotation or residual infall but can be explained by warm, dense, slowly outflowing material

We present observations of 13 CO J=6→5 emission from a variety of Galactic star-forming regions. Sources spanning a luminosity range from 1 to 106 L ○ . have been detected in this isotopic transition. The high line intensity (typically T mb =20-100 K) confirms the presence of large column densities (N H2 ≃10 23 cm −2 ) of warm (T kin ≥100 K) molecular gas in typical regions of massive star formation. The 13 CO/ 12 CO J=6→5 intensity ratio is typically much higher than the 13 CO/ 12 CO abundance ratio

We report the detection of carbon monoxide (CO) J=6-5 emission from the starburst nuclei of the galaxies NGC 253, M82, and IC 342. We have used the 6-5 transition as a thermometer of warm molecular gas in starburst nuclei, unambiguously finding that the nuclear molecular gas in starburst galaxies is substantially warmer than in typical disk clouds.

Using the 15 m James Clerk Maxwell Telescope, the molecular envelope surrounding the planetary nebula NGC 7027 was mapped in the J=3-2 line of 12 CO and the central position in the J=3-2 line of 13 CO and the J=2-1 lines of 12 CO and 13 CO observed. The J=3-2 12 CO map shows substantial deviations from spherical symmetry. The mass-loss rate along the nebula's polar axis appears to be about half that in the equatorial directions. Bright line wings are caused by a bipolar flow of molecular gas along the low-density axis. This gas has an outflow velocity of 23 km/s, larger than the 15 km/s expansion velocity of the bulk of the envelope.

IRAS 4 is a cold, low luminosity source in the active star formation region NGC 1333. The present sub-mm photometry and high spatial resolution 800- and 450-micron maps resolve this source into a binary system whose components are separated by about 31 arcsec and connected by a bridge of faint dust emission. The dust masses associated with the binary component are by far the largest seen toward any star of comparable luminosity, and are a factor of 10 higher than predicted by protostar models. It is suggested that these observations indicate a very young stellar system, possibly an actual protostar, in which most luminosity is generated by accretion. 27 refs.

The first astronomical detection of isotopic (C-13)O J = 6 - 5 emission at 661 GHz from the molecular clouds in Orion A and in NGC 2024 is reported. Strong lines indicate large column densities of warm, dense, molecular gas in these star formation regions. It is estimated that H2 column densities of gas with temperature of 100 K or more lie between 3 x 10 to the 22nd and 4 x 10 to the 23rd/sq cm. These column densities are difficult to explain by present theoretical heating models. In NGC 2024 and the Orion Bar, where lines are narrow, shock heating is very unlikely. The correlation of warm CO column density with UV intensity, also indicated by the nondetection of (C-13)O J = 6 - 5 emission toward the weak UV source NGC 2023, favors heating by UV radiation. However, present photodissociation region models fail to predict the large quantities of warm gas detected in NGC 2024 and in the Orion Bar. 32 refs.

High-angular resolution molecular hydrogen (H2) v = 1-0 S(1) line images of several well-known molecular outflow sources (DR 21, NGC 2071, HH 7-11, and HH 12) are presented. It is found that all of the outflow sources possess highly collimated jets of shock-excited gas that are extremely clumpy and often consist of bright knots that are placed periodically along the jet axis. The H2 emission-line jets are significantly more collimated than their corresponding CO outflows and remain collimated to large distances from their driving source. In DR 21 and NGC 2071, the H2 jets appear to become more collimated with increasing distance from the central source, suggesting that they are pressure-confined by the ambient cloud medium. In HH 7-11 and HH 12 the shock-excited ionized and molecular components are spatially coincident and appear to be of comparable shape and size; this suggests that the shocked gas is highly mixed on scales significantly smaller than the current spatial resolution.

A 144-sq-arcmin region of the Rho Oph star-forming cloud core was surveyed at 2.2 microns, complete to mK = 14. A total of 61 sources are detected, 26 of which have been previously reported, accounting for a total of 35 new sources with mK = 12-14. There is no turnover in the 2-micron luminosity function of the Rho Oph cloud core to a limiting sensitivity of mK = 14. Two of the newly discovered sources are binary companions to previously cataloged objects.