Search Publications
Solar Phenomena Associated with ``EIT Waves''
Thompson, B. J.; Biesecker, D. A.; Vourlidas, A. +2 more
In an effort to understand what an ``EIT wave'' is and what its causes are, we have looked for correlations between the initiation of EIT waves and the occurrence of other solar phenomena. An EIT wave is a coronal disturbance, typically appearing as a diffuse brightening propagating across the Sun. A catalog of EIT waves, covering the period from …
Measurement of Magnetic Helicity Injection and Free Energy Loading into the Solar Corona
Kusano, K.; Sakurai, T.; Yokoyama, T. +1 more
We develop a new methodology that can determine magnetic helicity flux as well as Poynting flux across the photosphere based on magnetograph observation. By applying this method, we study the injection mechanism of magnetic helicity and magnetic free energy into the solar corona. In order to derive the helicity and energy fluxes, first the velocit…
Toward a Mass and Radius Determination of the Nearby Isolated Neutron Star RX J185635-3754
Walter, Frederick M.; Neuhäuser, Ralph; Lattimer, James M. +3 more
We discuss efforts to determine the mass, radius, and surface composition of the nearby compact object RX J185635-3754 from its multiwavelength spectral energy distribution. We compute nonmagnetized model atmospheres and emergent spectra for selected compositions and gravities and discuss efforts to fit existing and new observational data from ROS…
Doppler Shift Oscillations of Hot Solar Coronal Plasma Seen by SUMER: A Signature of Loop Oscillations?
Solanki, S. K.; Curdt, W.; Innes, D. E. +2 more
We report observations of strongly damped Doppler shift oscillations detected in a flare line, Fe XIX, with the Solar Ultraviolet Measurement of Emitted Radiation spectrometer. Spectra were recorded above an active region at the western limb of the Sun, from lines with formation temperatures ranging from 0.01 to 10 MK. However, the oscillations we…
Hubble Space Telescope and Chandra Monitoring of the Crab Synchrotron Nebula
Gallagher, J. S.; Mori, K.; Hester, J. J. +6 more
We report the results of coordinated Hubble Space Telescope and Chandra observations of the Crab synchrotron nebula. Similar dynamical structures, including equatorial wisps moving outward at ~0.5c, are seen in both passbands. The inner X-ray ring is a variable, irregular structure from which wisps and diffuse emission emerge. The X-ray/visible je…
The White Dwarf Cooling Sequence of the Globular Cluster Messier 4
Rich, R. Michael; Gibson, Brad K.; Stetson, Peter B. +7 more
We present the white dwarf sequence of the globular cluster M4, based on a 123 orbit Hubble Space Telescope exposure, with a limiting magnitude of V~30 and I~28. The white dwarf luminosity function rises sharply for I>25.5, consistent with the behavior expected for a burst population. The white dwarfs of M4 extend to approximately 2.5 mag faint…
A High-Resolution X-Ray Image of the Jet in M87
Davis, D. S.; Marshall, H. L.; Harris, D. E. +4 more
We present the first high-resolution X-ray image of the jet in M87 using the Chandra X-Ray Observatory. There is clear structure in the jet and almost all of the optically bright knots are detected individually. The unresolved core is the brightest X-ray feature but is only 2-3 times brighter than knot A (12.3" from the core) and the inner knot HS…
Far-Infrared Galaxies in the Far-Ultraviolet
Sanders, D. B.; Steidel, Charles C.; Heckman, Timothy M. +4 more
In an effort to better understand the UV properties of ultraluminous infrared galaxies (ULIGs), and compare them to the rest-frame UV properties of high redshift submillimeter and Lyman-break galaxies, we have obtained far- and near-UV imaging observations (λeff=1457 and 2364 Å, respectively) of two luminous infrared galaxies (LIGs-VV 1…
Revised Stellar Temperatures for Magellanic Cloud O Supergiants from Far Ultraviolet Spectroscopic Explorer and Very Large Telescope UV-Visual Echelle Spectrograph Spectroscopy
Hillier, D. J.; Crowther, P. A.; Willis, A. J. +3 more
We have undertaken quantitative analysis of four LMC and SMC O4-9.7 extreme supergiants using far-ultraviolet FUSE, ultraviolet IUE/Hubble Space Telescope, and optical Very Large Telescope UV-Visual Echelle Spectrograph spectroscopy. Extended, non-LTE model atmospheres that allow for the consistent treatment of line blanketing, developed by Hillie…
A Statistical Study of Two Classes of Coronal Mass Ejections
Moon, Y. -J.; Yang, Guo; Wang, Haimin +4 more
A comprehensive statistical study is performed to address the question of whether two classes of coronal mass ejections (CMEs) exist. A total of 3217 CME events observed by SOHO/LASCO in 1996-2000 have been analyzed. We have examined the distributions of CMEs according to speed and acceleration, respectively, and investigated the correlation betwe…