Jeffrey G. Mangum

THE 2014 ALMA LONG BASELINE CAMPAIGN: FIRST RESULTS FROM HIGH ANGULAR RESOLUTION OBSERVATIONS TOWARD THE HL TAU REGION

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0. ′′ 075 (10 AU) to 0. ′′ 025 (3.5 AU), revealing an astonishing level of detail in the cir cumstellar disk surrounding the young solar analogue HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination (46.72 ◦ ± 0.05 ◦ ) and position angle (+138.02 ◦ ± 0.07 ◦ ). We obtain a high-fidelity image of the 1.0 mm spectral index (�), which ranges from � � 2.0 in the optically-thick central peak and two brightest ring s, increasing to 2.3-3.0 in the dark rings. The dark rings are not devoid of emission, and we estimate a grain emissivity index of 0.8 for the innermost dark ring and lower for subsequent dark rings, consistent with some degree of grain growth and evolution. Additional clues that the rings arise from planet formation incl ude an increase in their central offsets with radius and the presence of numerous orbital resonances. At a resolution of 35 AU, we resolve the molecular component of the disk in HCO + (1-0) which exhibits a pattern over LSR velocities from 2-12 km s -1 consistent with Keplerian motion around a �1.3M⊙ star, although complicated by absorption at low blue-shifted velocities. We also serendipitously detect and resolve the nearby protost ars XZ Tau (A/B) and LkH�358 at 2.9 mm. Subject headings: stars: individual (HL Tau, XZ Tau, LkH�358) — protoplanetary disks — stars: formation — submillimeter: planetary systems — techniques: interferometric

Synthesis imaging of the DR 21 (OH) cluster. II: Thermal ammonia and water maser emission

High-sensitivity, 4″ resolution images of the thermal ammonia and water maser emission have been made of the DR 21 (OH) molecular cloud. Images of the NH 3 (1,1) and (2,2) transitions show four primary emission regions embedded in a generally clumpy emission distribution. A total 18 ammonia cores are identified in these images. An analysis of the physical properties of these cores has shown that they are massive (M G ⇒15-1000 M ⊙ ) and warm (T k ⇒20 to greater than 80 K) with a range of sizes (θ s ⇒0.06-0.28 pc).

The On The Fly Imaging Technique

The On-The-Fly (OTF) imaging technique enables single-dish radio telescopes to construct images of small areas of the sky with greater efficiency and accuracy. This paper describes the practical application of the OTF imaging technique. By way of example the implementation of the OTF imaging technique at the NRAO 12 Meter Telescope is described. Specific requirements for data sampling, image formation, and Doppler correction are discussed.

CO: Twenty-Five Years of Millimeter-Wave Spectroscopy

Preface. Molecular Clouds in the Milky Way. Chemistry. Clouds and Cores. Star Formation. Instrumentation. Galaxies and Galactic Nuclei. CO in Planetary Systems and in Stellar Death. Reflections. Poster Abstracts. Author Index. Object Index. Subject Index. Participants.

FORMALDEHYDE DENSITOMETRY OF STARBURST GALAXIES

With a goal toward deriving the physical conditions in external galaxies, we present a survey of the formaldehyde emission in a sample of starburst systems. By extending a technique used to derive the spatial density in star formation regions in our own Galaxy, we show how the relative intensity of the 110-111 and 211-212 K-doublet transitions of H2CO can provide an accurate densitometer for the active star formation environments found in starburst galaxies. Relying on an assumed kinetic temperature and cospatial emission and absorption from both H2CO transitions, our technique is applied to a sample of 19 infrared-bright galaxies which exhibit various forms of starburst activity. In the five galaxies of our sample where both H2CO transitions were detected, we have derived spatial densities. We also use H2CO to estimate the dense gas mass in our starburst galaxy sample, finding similar mass estimates for the dense gas-forming stars in these objects as derived using other dense gas tracers. A related trend can be seen when one compares LIR to our derived n(H2) for the five galaxies within which we have derived spatial densities. Even though our number statistics are small, there appears to be a trend toward higher spatial density for galaxies with higher infrared luminosity. This is likely another representation of the LIR-Mdense correlation.

CO Observations toward Supernova Remnants with Associated OH 1720 MHz Masers

The environs of three supernova remnants (SNRs) with associated OH 1720 MHz masers, G349.7+0.2, CTB 37A, and G16.7+0.1, have been surveyed in the CO J = 1-0 transition with the 12 Meter Telescope of the NRAO, using the on-the-fly technique. These observations have revealed a number of molecular clouds interacting with the SNR shock fronts. Most of the OH 1720 MHz masers have been found to lie over CO concentrations, and the maser velocities are coincident with the CO peak velocities to an accuracy better than 2 km s-1. The present data trace the interstellar medium (ISM) structures interacting with the SNRs; however, to probe the shocked molecular gas in which the OH 1720 MHz emission originates, higher excitation transitions and more complex species should be observed. In CTB 37A, where the shock velocity into the molecular cloud could be determined, it has been found to be of C-type, in agreement with theoretical predictions. Part of the rim of G16.7+0.1 appears to be flattened by a dense external cloud, yet the only associated OH 1720 MHz maser lies near the opposite region of the remnant. This behavior, also observed in IC 443 and 3C 391, seems to contradict the suggestion that OH 1720 MHz maser emission occurs mainly for transverse shocks.

MAIN BEAM EFFICIENCY MEASUREMENTS OF THE CALTECH SUBMILLIMETER OBSERVATORY

We report main beam efficiency measurements at 211-365 GHz of the Caltech Submillimeter Observatory (OSO). These calculations are based on antenna temperature measurements of Mars, Jupiter, Saturn, and the Moon. We also present an analysis and review of the broadband millimeter and submillimeter continuum emission properties of Mars, Jupiter, Saturn, and the Moon. Through this analysis we establish a set of recommended main beam efficiencies for the facility receivers at the CSO.

How to Calculate Molecular Column Density

The calculation of the molecular column density from molecular spectral (rotational or ro-vibrational) transition measurements is one of the most basic quantities derived from molecular spectroscopy. Starting from first principles where we describe the basic physics behind the radiative and collisional excitation of molecules and the radiative transfer of their emission, we derive a general expression for the molecular column density. As the calculation of the molecular column density involves a knowledge of the molecular energy level degeneracies, rotational partition functions, dipole moment matrix elements, and line strengths, we include generalized derivations of these molecule-specific quantities. Given that approximations to the column density equation are often useful, we explore the optically thin, optically thick, and low-frequency limits to our derived general molecular column density relation. We also evaluate the limitations of the common assumption that the molecular excitation temperature is constant, and address the distinction between beam- and source-averaged column densities. We conclude our discussion of the molecular column density with worked examples for C

Synthesis imaging of the DR 21(OH) cluster. I - Dust continuum and C(O-18) emission

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Evaluation of the ALMA Prototype Antennas

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