Interpretation of Infrared Vibration-Rotation Spectra of Interstellar and Circumstellar Molecules

Infrared vibration-rotation lines can be valuable probes of interstellar and circumstellar molecules, especially symmetric molecules, which have no pure rotational transitions. But most such observations have been interpreted with an isothermal absorbing slab model, which leaves out important radiative transfer and molecular excitation effects. A more realistic non-LTE and non-isothermal radiative transfer model has been constructed. The results of this model are in much better agreement with the observations, including cases where lines in one branch of a vibration-rotation band are in absorption and another in emission. In general, conclusions based on the isothermal absorbing slab model can be very misleading, but the assumption of LTE may not lead to such large errors, particularly if the radiation field temperature is close to the gas temperature.Comment: 10 pages, 5 figures, ApJ in pres

Absolute Properties of the Eclipsing Binary Star V501 Herculis

V501 Her is a well detached G3 eclipsing binary star with a period of 8.597687 days for which we have determined very accurate light and radial-velocity curves by using robotic telescopes. Results of these data indicate that the component stars have masses of 1.269 +/- 0.004 and 1.211 +/- 0.003 solar masses, radii of 2.001 +/- 0.003 and 1.511 +/- 0.003 solar radii, and temperatures of 5683 +/- 100K and 5720 +/- 100K, respectively. Comparison with the Yonsei-Yale series of evolutionary models results in good agreement at an age of about 5.1 Gyr for a somewhat metal rich composition. Those models indicate that the more massive, larger, slightly cooler star is just beyond core hydrogen exhaustion while the less massive, smaller, slightly hotter star has not quite reached core hydrogen exhaustion. The orbit is not yet circularized, and the components are rotating at or near their pseudosynchronous velocities. The distance to the system is 420 +/- 30 pc

The Infrared Nucleus of the Wolf-Rayet Galaxy Henize 2-10

We have obtained near-infrared images and mid-infrared spectra of the starburst core of the dwarf Wolf-Rayet galaxy He 2-10. We find that the infrared continuum and emission lines are concentrated in a flattened ellipse 3-4'' or 150 pc across which may show where a recent accretion event has triggered intense star formation. The ionizing radiation from this cluster has an effective temperature of 40,000 K, corresponding to $30M_\odot$ stars, and the starburst is $0.5-1.5 \times 10^7$ years old.Comment: 17 pages Latex, 7 postscript figures, 1 postscript table, accepted to A

Ionized Gas in the Galactic Center: New Observations and Interpretation

We present new observations of the [Ne II] emission from the ionized gas in Sgr A West with improved resolution and sensitivity. About half of the emission comes from gas with kinematics indicating it is orbiting in a plane tipped about 25\degree\ from the Galactic plane. This plane is consistent with that derived previously for the circumnuclear molecular disk and the northern arm and western arc ionized features. However, unlike most previous studies, we conclude that the ionized gas is not moving along the ionized features, but on more nearly circular paths. The observed speeds are close to, but probably somewhat less than expected for orbital motions in the potential of the central black hole and stars and have a small inward component. The spatial distribution of the emission is well fitted by a spiral pattern. We discuss possible physical explanations for the spatial distribution and kinematics of the ionized gas, and conclude that both may be best explained by a one-armed spiral density wave, which also accounts for both the observed low velocities and the inward velocity component. We suggest that a density wave may result from the precession of elliptical orbits in the potential of the black hole and stellar mass distribution.Comment: 28 pages, 13 figures, ApJ in pres

Artificial Pothole and Level Ditch Development as a Means of Increasing Waterfowl Production

The glaciated prairie pothole country of the Midwest forms a vital segment of the most important waterfowl breeding habitat in North America. Here are hatched three-quarters of all the ducks raised in the United States. During a recent seven-year period the three-state area of Minnesota and the Dakotas produced an average of 4 to 5 million ducks annually (Janzon, 1947). This wetland region which once comprised 115,000 square miles in five states had shrunk to about 56,000 square miles by 19.56 (Lynch, 1956). To maintain the pre,;ent rate of waterfowl production in the face of continued destruction of habitat through drainage and other land use practices detrimental to breeding ducks will require that remaining wet lands, particularly those in public ownership, be developed as much .as possible toward their maximum potential for waterfowl production. In recent years the U. S. Fish and Wildlife Service has excavated several hundred experimental artificial potholes and level ditches on its refuges in the Dakotas and Minnesota. It was believed that these water areas would increase the number of ducks breeding on the refuge marshes by providing additional territorial sites. Before more funds are invested to expand this work it is important to determine the success of the existing development in meeting this objective. This study, to evaluate the artificial pothole and level ditch development, was initiated. in 1957 by the U.S. Fish and Wildlife Service at Lower Souris National Wildlife Refuge in North Dakota. The project was carried out in collaboration with the Utah Cooperative wildlife Research Unit and the Department of Wildlife Management, Utah State University