Search Publications
Inverse Compton X-rays from the radio galaxy 3C 219
Bondi, M.; Brunetti, G.; Comastri, A. +3 more
We report the results from a Chandra observation of the powerful nearby (z= 0.1744) radio galaxy 3C 219. We find evidence for non-thermal X-ray emission from the radio lobes which fits fairly well with a combination of inverse Compton scattering of Cosmic Microwave Background radiation and of nuclear photons with the relativistic electrons in the …
Adaptive Optics Imaging and Spectroscopy of Cygnus A. I. Evidence for a Minor Merger
Canalizo, Gabriela; Dahm, Scott E.; Antonucci, Robert +2 more
We present Keck II adaptive optics near-infrared imaging and spectroscopic observations of the central regions of the powerful radio galaxy Cyg A. The 0.05" resolution images clearly show an unresolved nucleus between two spectacular ionization/scattering cones. We report the discovery of a relatively bright (K'~19) secondary point sour…
The Identification of Infrared Synchrotron Radiation from Cassiopeia A
Rudnick, L.; Jones, T. J.; DeLaney, T. +1 more
We report the discovery of polarized flux at 2.2 µm from the bright shell of the ~320 yr old supernova remnant Cas A. The fractional polarizations are comparable at 6 cm and 2.2 µm, and the polarization angles are similar, demonstrating that synchrotron radiation from the same relativistic plasma is being observed at these widely separ…
A Quantitative Method to Optimise Magnetic Field Line Fitting of Observed Coronal Loops
Wiegelmann, T.; Hood, A. W.; Carcedo, L. +2 more
Many authors use magnetic-field models to extrapolate the field in the solar corona from magnetic data in the photosphere. The accuracy of such extrapolations is usually judged qualitatively by eye, where a less judgemental quantitative approach would be more desirable. In this paper, a robust method for obtaining the best fit between a theoretica…
Kink mode oscillation of the current sheet
Balogh, A.; Zhang, T. L.; Glassmeier, K. -H. +6 more
Oscillations of the current sheet observed by the Cluster spacecraft are investigated, using the special ability of Cluster to separate between spatial and temporal variations. We find that before substorm onset, a thin current sheet moves with a velocity of 10 km/s mainly in the vertical direction; after substorm onset the current sheet thickens …
High-Resolution Near-Infrared Imaging and Polarimetry of Four Proto-Planetary Nebulae
Kwok, Sun; Hrivnak, Bruce J.; Su, Kate Y. L. +1 more
High-resolution near-infrared Hubble Space Telescope (HST) NICMOS (F160W, F222M) images and polarization (2 µm) observations were made of four bipolar proto-planetary nebulae (PPNs): IRAS 17150-3224, 17441-2411, 17245-3951, and 16594-4656. The first three of these are viewed nearly edge-on, and for the first time the central stars in them ar…
Two Embedded Young Stellar Objects in NGC 2264 with FU Orionis Characteristics
Reipurth, Bo; Aspin, Colin
We report the discovery of two young stars in the NGC 2264 star-forming molecular cloud whose physical and morphological characteristics are similar to FU Orionis objects. The objects form a close pair and exhibit a curved reflection nebula in the near-IR. The brighter of the two stars, AR 6A, is optically visible but considerably reddened, has a …
Neptune's far-infrared spectrum from the ISO long-wavelength and short-wavelength spectrometers
Swinyard, Bruce M.; Orton, Glenn S.; Feuchtgruber, Helmut +4 more
Neptune was observed by the Infrared Space Observatory (ISO) Long-Wavelength Spectrometer (LWS) between 46 and 185 µm. At wavelengths between 50 and 110 µm the accuracy of these measurements is ⩽0.3 K. Observations of this planet made by the ISO Short-Wavelength Spectrometer between 28 and 44 µm were combined with the LWS data to…
Properties of narrow coronal mass ejections observed with LASCO
Howard, R. A.; Gopalswamy, N.; Michalek, G. +1 more
We report the statistical properties of narrow coronal mass ejections (CMEs, angular width < 20°) withparticular emphasis on comparison with normal CMEs. We investigated 806 narrow CMEs from an online LASCO/CME catalog and found that (1) the fraction of narrow CMEs increases from 12% to 22% towards solar maximum, (2) during the solar maximum, t…
Nuclear Activity and Massive Star Formation in the Low-Luminosity Active Galactic Nucleus NGC 4303: Chandra X-Ray Observations
Mas-Hesse, J. M.; Colina, L.; Guainazzi, M. +4 more
We present evidence of the coexistence of either an AGN or an ultraluminous X-ray source, together with a young superstellar cluster, in the central 3 pc of NGC 4303. The galaxy contains a low-luminosity AGN and hosts a number of starburst regions in a circumnuclear spiral, as well as in the nucleus itself. A high spatial resolution Chandra image …