Hot and Diffuse Clouds near the Galactic Center Probed by Metastable H3+

Using an absorption line from the metastable (J, K) = (3, 3) level of H3+ together with other lines of H3+ and CO observed along several sightlines, we have discovered a vast amount of high temperature (T ~ 250 K) and low density (n ~ 100 cm-3) gas with a large velocity dispersion in the Central Molecular Zone (CMZ) of the Galaxy, i.e., within 200 pc of the center. Approximately three fourths of the H3+ along the line of sight to the brightest source we observed, the Quintuplet object GCS 3-2, is inferred to be in the CMZ, with the remaining H3+ located in intervening spiral arms. About half of H3+ in the CMZ has velocities near ~ - 100 km s-1 indicating that it is associated with the 180 pc radius Expanding Molecular Ring which approximately forms outer boundary of the CMZ. The other half, with velocities of ~ - 50 km s-1 and ~ 0 km s-1, is probably closer to the center. CO is not very abundant in those clouds. Hot and diffuse gas in which the (3, 3) level is populated was not detected toward several dense clouds and diffuse clouds in the Galactic disk where large column densities of colder H3+ have been reported previously. Thus the newly discovered environment appears to be unique to the CMZ. The large observed H3+ column densities in the CMZ suggests an ionization rate much higher than in the diffuse interstellar medium in the Galactic disk. Our finding that the H3+ in the CMZ is almost entirely in diffuse clouds indicates that the reported volume filling factor (f ≥ 0.1) for n ≥ 104 cm-3 clouds in the CMZ is an overestimate by at least an order of magnitude.Comment: 33 pages, 5 figures, 3 table

Shellfish Culture Forum: Industry Issues An Annual Evaluation 2002

Virginia Institute of Marine Scienc

Clam Culture: The Possibilities and the Pitfalls

Clam culture in-Virginia has recently received a ·great deal of attention due to the declining production of wild fishery stocks, and to the apparent success of some commercial clam farms. A 1994 survey of Virginia aquaculture by the Virginia Agricultural Statistics Service identified hard clams as the most valuable cultured product in the Commonwealth; production in 1993 exceeded $11 million in gross sales. Be wary of reports that clam farming is easy and guarantees financial rewards. Farming clams is much more complicated than throwing clams overboard and returning a few years later to harvest them for market. The financial risks associated with aquaculture ventures can be substantial, depending upon your scale of operation and any loan equity you may have committed

First Acetic Acid Survey with CARMA in Hot Molecular Cores

Acetic acid (CH$_3$COOH) has been detected mainly in hot molecular cores where the distribution between oxygen (O) and nitrogen (N) containing molecular species is co-spatial within the telescope beam. Previous work has presumed that similar cores with co-spatial O and N species may be an indicator for detecting acetic acid. However, does this presumption hold as higher spatial resolution observations become available of large O and N-containing molecules? As the number of detected acetic acid sources is still low, more observations are needed to support this postulate. In this paper, we report the first acetic acid survey conducted with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at 3 mm wavelengths towards G19.61-0.23, G29.96-0.02 and IRAS 16293-2422. We have successfully detected CH$_3$COOH via two transitions toward G19.61-0.23 and tentatively confirmed the detection toward IRAS 16293-2422 A. The determined column density of CH$_3$COOH is 2.0(1.0)$\times 10^{16}$ cm$^{-2}$ and the abundance ratio of CH$_3$COOH to methyl formate (HCOOCH$_3$) is 2.2(0.1)$\times 10^{-1}$ toward G19.61-0.23. Toward IRAS 16293 A, the determined column density of CH$_3$COOH is $\sim$ 1.6 $\times 10^{15}$ cm$^{-2}$ and the abundance ratio of CH$_3$COOH to methyl formate (HCOOCH$_3$) is $\sim$ 1.0 $\times 10^{-1}$ both of which are consistent with abundance ratios determined toward other hot cores. Finally, we model all known line emission in our passband to determine physical conditions in the regions and introduce a new metric to better reveal weak spectral features that are blended with stronger lines or that may be near the 1-2$\sigma$ detection limit.Comment: 28 pages, 8 figures, accepted for publication in the ApJ; Revised citation in session 2, references remove