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Cloud Fragmentation and Proplyd-like Features in H II Regions Imaged by the Hubble Space Telescope
O'Dell, C. R.; De Marco, Orsola; Rubin, R. H. +2 more
We have analyzed Hubble Space Telescope ACS and WFPC2 new and archival images of eight H II regions to look for new protoplanetary disks (proplyds) similar to those found in the Orion Nebula. We find a wealth of features similar in size (although many are larger) to the bright cusps around the Orion Nebula proplyds. None of them, however, contains…
Mass Modeling of Abell 1689 Advanced Camera for Surveys Observations with a Perturbed Navarro-Frenk-White Model
Ford, H. C.; Jee, M. J.; Illingworth, G. D. +7 more
The combined resolution and sensitivity of the Advanced Camera for Surveys deep imaging provides the capability of high-accuracy lens modeling of Abell 1689. Originally based on the technique of Broadhurst and coworkers, our software is designed to provide a precise and efficient method of modeling cluster lenses without assumptions relating the l…
Application of a New Technique for Deriving Prominence Mass from SOHO EIT Fe XII (19.5 nm) Absorption Features
Gilbert, Holly R.; Holzer, Thomas E.; MacQueen, R. M. +1 more
In a previous study we developed a new technique for deriving prominence mass by observing how much coronal radiation in the Fe XII (19.5 nm) spectral line is absorbed by prominence material. In the present work we apply this new method, which allows us to consider the effects of both foreground and background radiation in our calculations, to a s…
The Warped Circumstellar Disk of HD 100546
Quillen, Alice C.
We propose that the two-armed spiral features seen in visible Hubble Space Telescope images of scattered light in HD 100546's circumstellar disk are caused by the illumination of a warped outer disk. A tilt of 6°-15° from the symmetry plane can cause the observed surface brightness variations, providing the disk is very twisted (highly warped) at …
XMM-Newton View of the z > 0 Warm-Hot Intergalactic Medium toward Markarian 421
Elvis, Martin; Williams, Rik J.; Nicastro, Fabrizio +1 more
The recent detection with Chandra of two warm-hot intergalactic medium (WHIM) filaments toward Mrk 421 by Nicastro et al. provides a measurement of the bulk of the ``missing baryons'' in the nearby universe. Since Mrk 421 is a bright X-ray source, it is also frequently observed by the XMM-Newton Reflection Grating Spectrometer (RGS) for calibratio…
Waves in Jupiter's atmosphere observed by the Cassini ISS and CIRS instruments
West, Robert A.; Porco, Carolyn C.; Achterberg, Richard K. +7 more
The Cassini Imaging Science Subsystem (ISS) and Composite Infrared Spectrometer (CIRS) reported a North Equatorial Belt (NEB) wave in Jupiter's atmosphere from optical images [Porco, C.C., and 23 colleagues, 2003. Science 299, 1541-1547] and thermal maps [Flasar, F.M., and 39 colleagues, 2004. Nature 427, 132-135], respectively. The connection bet…
Direct Measurements of Energetic Neutral Hydrogen in the Interplanetary Medium
Fedorov, A.; Barabash, S.; Lundin, R. +16 more
We present an analysis of hydrogen energetic neutral atoms (ENAs) measured by the ASPERA-3 instrument on board Mars Express. We focus on ENAs that have no Martian origin. The energy spectra of these ENAs are all very similar and can be fitted well by a two-component power law. The fluxes, integrated from 0.2 to 10 keV, vary between 5×103
Shrinking and Cooling of Flare Loops in a Two-Ribbon Flare
Lin, Jun; Temmer, Manuela; Veronig, Astrid +2 more
We analyze the evolution of the flare/postflare-loop system in the two-ribbon flare of November 3, 2003, utilizing multi-wavelength observations that cover the temperature range from several tens of MK down to 104 K. A non-uniform growth of the loop system enables us to identify analogous patterns in the height-time, h(t), curves measur…
Striated auroral kilometric radiation emission: A remote tracer of ion solitary structures
Gurnett, D. A.; Menietti, J. D.; Mutel, R. L. +2 more
We describe the statistical properties of narrowband drifting auroral kilometric radiation ("striated" AKR) based on observations from the Cluster wideband receiver during 2002-2005. We show that the observed characteristics, including frequency drift rate and direction, narrow bandwidth, observed intensity, and beaming angular sizes are all consi…
Electrostatic solitary structures observed at Saturn
Gurnett, D. A.; Dougherty, M. K.; Kurth, W. S. +2 more
We report observations of electric field solitary structures, measured by the Cassini Radio and Plasma Wave Science (RPWS) instrument in the vicinity of Saturn's magnetosphere with ambient magnetic fields that range from ~0.1 nT to 8000 nT. The peak-to-peak electric field amplitudes of the observed solitary structures range from a few µV/m t…