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Submillimeter Array Imaging of the Maser Emission from the \(H30\alpha\) Radio Recombination Line in MWC 349A
(American Astronomical Society, 2008)
We used the Submillimeter Array to map the angular distribution of the H30α recombination line (231.9 GHz) in the circumstellar region of the peculiar star MWC 349A. The resolution was 1.2'', but because of high signal-to-noise ...
The Collimated Jet Source in IRAS 16547-4247: Time Variation, Possible Precession, and Upper Limits to the Proper Motions along the Jet Axis
(American Astronomical Society, 2008)
The triple radio source detected in association with the luminous infrared source IRAS 16547-4247 has previously been studied with high angular resolution and high sensitivity with the Very Large Array at 3.6 cm wavelength. ...
The Parsec‐Scale Accretion Disk in NGC 3393
(American Astronomical Society, 2008)
We present a Very Long Baseline Interferometry image of the water maser emission in the nuclear region of NGC 3393. The maser emission has a linear distribution oriented at a position angle of ~–34°, perpendicular to both ...
Infall and Outflow of Molecular Gas in Sgr B2
(American Astronomical Society, 2008)
Observations of two \(H_2CO (3_{03}-2_{02} and 3_{21}-2_{20})\) lines and continuum emission at 1.3 mm toward Sgr B2(N) and Sgr B2(M) have been carried out with the SMA. The mosaic maps of Sgr B2(N) and Sgr B2(M) in both ...
Toward a New Geometric Distance to the Active Galaxy NGC 4258. II. Centripetal Accelerations and Investigation of Spiral Structure
(American Astronomical Society, 2008)
We report measurements of centripetal accelerations of maser spectral components of NGC 4258 for 51 epochs spanning 1994 to 2004. This is the second paper of a series, in which the goal is the determination of a new geometric ...
An X‐Ray, Infrared, and Submillimeter Flare of Sagittarius A*
(American Astronomical Society, 2008)
Energetic flares are observed in the Galactic supermassive black hole Sagittarius A* from radio to X-ray wavelengths. On a few occasions, simultaneous flares have been detected in IR and X-ray observations, but clear ...
Event-Horizon-Scale Structure in the Supermassive Black Hole Candidate at the Galactic Centre
(Nature Publishing Group, 2008)
The cores of most galaxies are thought to harbour supermassive black holes, which power galactic nuclei by converting the gravitational energy of accreting matter into radiation. Sagittarius A* (Sgr A*), the compact source ...
The Black-Hole Accretion Disk in NGC 4258: One of Nature’s Most Beautiful Dynamical Systems
(Astronomical Society of the Pacific, 2008)
In this talk I will summarize some of the work that the CfA group has done to study the structure of the water masers in the accretion disk of NGC4258. A series of 18 epochs of VLBA data taken from 1997.3 to 2000.8 were ...
Parity Violation Constraints Using Cosmic Microwave Background Polarization Spectra from 2006 and 2007 Observations by the QUaD Polarimeter
(American Physical Society, 2009)
We constrain parity-violating interactions to the surface of last scattering using spectra from the QUaD experiment’s second and third seasons of observations by searching for a possible systematic rotation of the polarization ...
Second and Third Season QUaD Cosmic Microwave Background Temperature and Polarization Power Spectra
(IOP Publishing, 2009)
We report results from the second and third seasons of observation with the QUaD experiment. Angular power spectra of the cosmic microwave background are derived for both temperature and polarization at both 100 GHz and ...