Browsing FAS Scholarly Articles by Author "Humphreys, E. M. L."
Now showing items 1-4 of 4
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First Detection of Millimeter/Submillimeter Extragalactic H2O Maser Emission
Humphreys, E. M. L.; Greenhill, L. J.; Reid, M. J.; Beuther, H.; Moran, James M.; Gurwell, Mark Andrew; Wilner, David J.; Kondratko, P. T. (IOP Publishing, 2005)We report the first detection of an extragalactic millimeter wavelength H2O maser at 183 GHz towards NGC 3079 using the Submillimeter Array (SMA), and a tentative submillimeter wave detection of the 439 GHz maser towards ... -
Toward a New Geometric Distance to the Active Galaxy NGC 4258. I. VLBI Monitoring of Water Maser Emission
Argon, A; Greenhill, Lincoln Jared; Reid, Mark Jonathan; Moran, James M.; Humphreys, E. M. L. (IOP Publishing, 2007)We report a three year, 18 epoch, VLBI monitoring study of H 2O masers in the sub-parsec, warped, accretion disk within the NGC 4258 AGN. Our immediate goals are to trace the geometry of the underlying disk, track rotation ... -
Toward a New Geometric Distance to the Active Galaxy NGC 4258. II. Centripetal Accelerations and Investigation of Spiral Structure
Humphreys, E. M. L.; Reid, Mark Jonathan; Greenhill, Lincoln J.; Moran, James M.; Argon, Alice L. (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 ... -
Toward a New Geometric Distance To the Active Galaxy NGC 4258. III. Final Results and The Hubble Constant
Humphreys, E. M. L.; Reid, Mark Jonathan; Moran, James M.; Greenhill, Lincoln Jared; Argon, Alice L. (American Astronomical Society, 2013)We report a new geometric maser distance estimate to the active galaxy NGC 4258. The data for the new model are maser line-of-sight (LOS) velocities and sky positions from 18 epochs of very long baseline interferometry ...