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We describe a method for fiding substellar-mass self-gravitating clumps (proto-brown dwarfs) in nearby molecular clouds, using millimeter-wave telescopes. This method represents a novel approach to looking for brown dwarfs and, for the nearest molecular clouds, has a greater mass, sensitivity than traditional methods. We describe how the method can distinguish between various functional forms of the low-mass (

A new 12 CO survey of the Galactic center region reveals a nearly continuous ring of molecular gas that is centered on and concentric with the nonthermal radio continuum shell G359.1-0.5. The molecular feature has high radial velocities, between -60 and -190 km/s, indicating that it is likely to be located at the distance of the Galactic center; its diameter is then about 75 pc. The mass of the ring, based on its integrated CO line emission, is about 2.5 x 10 6 M ⊙

New millimeter-wavelength observations indicate that the L1551 star-forming region may be more complex than previously thought. CO and CS maps of a nearly 1 deg 2 region show that multiple outflows confuse the interpretation of the structure of the L1551/IRS 5 and HL/YZ Tau molecular outflows. A 8' (0.4 pc) long, collimated redshifted molecular ridge lies near the northern rim of the redshifted lobe of the L1551 CO outflow. Its position and orientation indicates that it may be an outflow associated with the 2' long HH-30 optical jet

At a distance of 65 pc, the molecular cloud MBM 12 is the nearest molecular complex known. Results of extensive molecular and preliminary atomic spectral mapping of the MBM 12 complex are reported. The total H2 mass of the cloud is estimated to be about 30 solar masses. Although there are over 50 distinct emission clumps and the (C-13)O (J = 1-0) maps show structure within the MBM 12 complex down to the resolution limit of about 6500 AU. The large line widths may reflect either the evaporation of the clumps by the ambient hot gas or the presence of an ensemble of blended emission clumps that are smaller than the resolution limit. Preliminary results show H I envelopes about the molecular cores with column densities consistent with that expected for atomic to molecular transition regions. The kinematics of the MBM 12 complex imply kinetic energies of about 10 to the 45th ergs. This energy is typical of that produced by a bipolar flow from a young stellar object. 30 refs.

The nearby molecular clouds MBM 7, 12, 30, 32, 40, 41, and 55 were surveyed for tracers of dense gas, including the (1-0), (2-1), and (3-2) rotational lines of CS and the (1-0) lines of HCO(+) and HCN. MBM 7 and MBM 12 contain dense cores, while the other clouds contain little or no traces of dense gas. Comparison of the emission from dense gas tracers to that of (13)CO reveals that the former are more compact in angular size as well as line width. An extensive CS(2-1) survey of part of MBM 12 reveals that the emission is characterized by clumps on approximately 3 min scales as well as extended emission. Observations of the CS(1-0) and (3-2) lines using telescopes with matched beam sizes reveal that the volume density must be at least approximately 10(exp 4.5)/cc within the (3-2) emitting regions, which are approximately 0.03 pc in radius. Electron excitation of the CS rotational levels is ruled out (in the cores) by comparing the (3-2)/(1-0) line ratios with models including H2 and electron collisions. The volume density in the cores is substantially larger than in the portions of the cloud traced by CO emission. The density increases into the cores as r(exp -2), suggesting dynamical collapse. The masses of the cores are close to the virial mass, suggesting they are dynamically bound. The cores in MBM 7 and MBM 12 are thus likely to form stars; they are the nearest sites of star formation.

Using plates obtained with the Mauna Kea 2.2-m telescope on October 26, 1979, a color-magnitude diagram of the open cluster Mel 71 is produced. A photoelectric sequence was obtained with the CTIO 0.9-m telescope on November 14, 1979 using an S-11 photomultiplier and CTIO UBV filter set. From a Hyades ZAMS fit, it is deduced that Mel 71 has an E(B-V) reddening of 0.10, an (m-M)0 distance modulus of 11.88, and a (B-V)0 corrected main-sequence turnoff color index of 0.18. The estimated age of 9.930 million years is over twice as old as previously calculated. The picture is consistent with that of a typical outer-disk cluster.

Millimeter-wave, near-IR, and 21 cm observations of the radio source G70.7 + 1.2 , which has been proposed to be a recent SNR developing inside a molecular cloud, are presented. A small molecular cloud with properties similar to a large dark cloud or globule is interacting with the nonthermal radio continuum source. The molecular cloud has a lumpy structure with its highest column density portion lying just outside the brightest portion of the radio continuum shell. If the radio source was produced by a supernova explosion, its kinetic energy was several orders of magnitude less than that of most observed supernovae. An OB star wind with certain characteristics is sufficient to drive the bubble, but the high radio continuum nonthermal surface brightness and polarization of the object is not explained by this model. 23 references.