Millimeter and submillimeter line surveys of the proto binary source IRAS 16293-2422 are presented in the 230 and 345 GHz windows. In total, 265 lines belonging to 44 molecules and their isotopomers (24 chemically different species) have been detected. Here the data for organic and deuterated molecules are considered; the results for Si-and Shearing species have been discussed in an earlier paper (Blake et al. 1994). The observations have been analyzed through a combination of rotation diagrams and full statistical equilibrium/ radiative transfer calculations. At least three physically and chemically different components can be distinguished within the 20" (3000 AU) beam. The first component is the warm (1icin;;;:; 80 K) and dense [n(H2) ~ (0.5-1) x 10 7 cm-3 ] gas sampled by Si-and S-containing molecules such as SiO and S0 2 • This gas is found to be rich in organic molecules such as CH30H, CH 3 CN, and H2CO, as well. It is only 3"-10" in size (500-1500 AU) and most likely represents the interaction of the bipolar outflow(s) with the circumbinary envelope. The second component is the circumbinary envelope itself, which has Tkin ~ 40 K and n(H 2) ~ 10 6-10 7 cm-3 and is 10"-15" in size (2000 AU). It contains common molecules like CS, Hco+, and H 2 CO. The third component is the colder, lower density outer part of the envelope, which gradually fades into the ambient surrounding cloud core [Tkin ~ 10-20 K; n(H 2) ~ (3 x 10 4)-(2 x 10 5) cm-3 ]. Radicals such as CN, C2H, and C3H 2 appear to reside principally in this region. The ambient cloud material is also probed through self-absorbed features in the line profiles of molecules such as HCN, HCO +, and H 2 CO. Beam-averaged abundances over a 20" scale are presented and are compared with those observed in cold dark clouds such as L134N and TMC-1 and with high-mass star-forming cores such as Orion-KL. Remarkably high deuterium fractionation ratios are found, which are more characteristic of hot core regions than of cold, quiescent clouds. As a whole, the chemical and physical regimes that can be distinguished in the low-mass young stellar object IRAS 16293-2422 are qualitatively similar to those found in high-mass star-forming regions, confirming the earlier conclusion that the chemical composition depends more on the age of the object than its mass.

We present a high-sensitivity spectral line survey of the high-mass star-forming region Orion KL in the 325-360 GHz frequency band. The survey was conducted at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii. The sensitivity achieved is typically 0.1-0.5 K and is limited mostly by the sideband separation method utilized. We find 717 resolvable features consisting of 1004 lines, among which 60 are unidentified. The identified lines are due to 34 species and various isotopomers. Most of the unidentified lines are weak, and many of them most likely due to isotopomers or vibrationally or torsionally excited states of known species with unknown line frequencies, but a few reach the 2-5 K level. No new species have been identified, but we were able to strengthen evidence for the identification of ethanol in Orion and found the first nitrogen sulfide line in this source. The molecule dominating the integrated line emission is S02, which emits twice the intensity of CO, followed by SO, which is only slightly stronger than CO. In contrast, the largest number of lines is emitted from heavy organic rotors like HCOOCH3, CH3CH2CN, and CH3OCH3, but their contribution to the total flux is unimportant. CH3OH is also very prominent, both in the number of lines and in integrated flux. An interesting detail of this survey is the first detection of vibrationally excited HCN in the v2 = 2 state, 2000 K above ground. Clearly this is a glimpse into the very inner part of the Orion hot core.

Molecular line surveys and fully sampled spectral line maps at 1.3 and 0.87 mm are used to examine the physical and chemical characteristics of the extreme Class I sources IRAS 4A and 4B in the L1450/NGC 1333 molecular cloud complex. A very well collimated, jetlike molecular outflow emanates from IRAS 4A, with a dynamical age of a few thousand years. Symmetric, clumpy structure along the outflow lobes suggests that there is considerable variability in the mass-loss rate or wind velocity even at this young age. Molecular emission lines toward IRAS 4A and 4B are observed to be weak in the velocity range corresponding to quiescent material surrounding the young stellar objects (YSOs). Depletion factors of 10-20 are observed for all molecules, including CO, even for even for very conservative mass estimates from the measured millimeter and submillimeter dust continuum. However, abundances scaled with respect to CO are similar to other dark molecular cloud cores. Such depletions could be mimicked by high dust optical depths or increased grain emissivities at the observing frequencies of 230 and 345 GHz, but the millimeter and submillimeter spectral energy distributions suggest that this is unlikely over the single-dish size scales of 5000-10,000 AU. Dense, outflowing gas is found to be kinematically, but not spatially, distinct from the quiescent material on these size scales. If CO is used as a chemical standard for the high-velocity gas, we find substantial enhancements in the abundances of several molecules in outflowing material, most notably CS, SiO, and CH3OH. The SiO emission is kinematically well displaced from the bulk cloud velocity and likely arises from directly shocked material. As is the case for CO, however, the outflow features from more volatile species are centered near the cloud velocity and are often characterized by quite low rotational temperatures. We suggest that grain-grain collisions induced by velocity shear zones surrounding the outflow axes transiently desorb the grain mantles, resulting in large abundance enhancements of selected species. Similar results have recently been obtained in several other low-mass YSOs, where the outflowing gas is often both kinematically and spatially distinct, and are illustrative of the ability of accretion and outflow processes to simultaneously modify the composition of the gas and dust surrounding young stars.

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Abstract. Results are presented of the 345 GHz spectral survey toward three sources in the W 3 Giant Molecular Cloud: W 3 IRS4, W 3 IRS5 and W 3(H 2 O). Nearly 90% of the atmospheric window between 334 and 365 GHz has been scanned using the James Clerk Maxwell Telescope (JCMT 1 ) down to a noise level of ∼ 80 mK per resolution element. These observations are complemented by a large amount of data in the 230 GHz atmospheric window. From this data set physical conditions and beam-averaged column densities are derived for more than 14 chemically different species (over 24 different isotopes). The physical parameters derived in Paper I (Helmich et al. 1994) are confirmed by the analysis of the excitation of other species, although there is evidence that the silicon-and sulfurbearing molecules exist in a somewhat denser and warmer environment. The densities are high, ≥ 10 6 cm −3 , in the three sources and the kinetic temperatures for the bulk of the gas range from 55 K for IRS4 to 220 K for W 3(H 2 O). The chemical differences between the three sources are very striking: silicon-and sulfur-bearing molecules such as SiO and SO 2 are prominent toward IRS5, whereas organic molecules like CH 3 OH, CH 3 OCH 3 and CH 3 OCHO are at least an order of magnitude more abundant toward W 3(H 2 O). Vibrationally excited molecules are also detected toward this source. Only simple molecules are found toward IRS4. The data provide constraints on the amount of deuterium fractionation and the ionization fraction in the observed regions as well. These chemical character- istics are discussed in the context of an evolutionary sequence, in which IRS5 is the youngest, W 3(H 2 O) somewhat older and IRS4, although still enigmatic, the oldest.