Search Publications
The Global Solar Wind Between 1 AU and the Termination Shock
Whang, Y. C.
This paper studies the global solar wind between 1 AU and the termination shock, taking into account the highly latitude dependent solar wind at the 1 AU boundary and the ionization of interstellar neutral hydrogen. A system of two-fluid magnetohydrodynamics equations governs the flow of solar wind plasma; the conditions of the solar wind at 1 AU …
Sub-surface Meridional Flow, Vorticity, and the Lifetime of Solar Active Regions
Maurya, R. A.; Ambastha, A.
Solar sub-surface fluid topology provides an indirect approach to examine the internal characteristics of active regions (ARs). Earlier studies have revealed the prevalence of strong flows in the interior of ARs having complex magnetic fields. Using the Doppler data obtained by the Global Oscillation Network Group project for a sample of 74 ARs, w…
Tomographic Reconstruction of the Three-dimensional Structure of the HH30 Jet
del Burgo, C.; De Colle, F.; Raga, A. C.
The physical parameters of Herbig-Haro (HH) jets are usually determined from emission-line ratios, obtained from spectroscopy or narrowband imaging, assuming that the emitting region is homogeneous along the line of sight. Under the more general hypothesis of axisymmetry, we apply tomographic reconstruction techniques to the analysis of HH jets. W…
X-ray Shadowing Experiments Toward Infrared Dark Clouds
Snowden, S. L.; Anderson, L. D.; Bania, T. M.
We searched for X-ray shadowing toward two infrared dark clouds (IRDCs) using the MOS detectors on XMM-Newton to learn about the Galactic distribution of X-ray emitting plasma. IRDCs make ideal X-ray shadowing targets of 3\over 4 keV photons due to their high column densities, relatively large angular sizes, and known kinematic distances. Here we …
Characteristics and Evolution of the Magnetic Field and Chromospheric Emission in an Active Region Core Observed by Hinode
Winebarger, Amy R.; Warren, Harry P.; Brooks, David H.
We describe the characteristics and evolution of the magnetic field and chromospheric emission in an active region core observed by the Solar Optical Telescope (SOT) on Hinode. Consistent with previous studies, we find that the moss is unipolar, the spatial distribution of magnetic flux evolves slowly, and that the magnetic field is only moderatel…
Cosmic Origins Spectrograph Observations of Translucent Clouds: Cyg OB2 8A
Danforth, Charles W.; Snow, Theodore P.; Destree, Joshua D. +3 more
Data from the Cosmic Origins Spectrograph (COS) are presented for the first highly reddened target (Cyg OB2 8A) under the COS Science Team's guaranteed time allocation. Column densities of ionic, atomic, and molecular species are reported and implications are discussed. Data from Cyg OB2 8A demonstrate the ability to analyze highly reddened inters…
Very High Energy Observations of Gamma-ray Bursts with STACEE
Fortin, P.; Aune, T.; Mukherjee, R. +14 more
Gamma-ray bursts (GRBs) are the most powerful explosions known in the universe. Sensitive measurements of the high-energy spectra of GRBs can place important constraints on the burst environments and radiation processes. Until recently, there were no observations during the first few minutes of GRB afterglows in the energy range between 30 GeV and…
New Results from the Magellan IMACS Spectroscopic Lyα Survey: NICMOS Observations of Lyα Emitters at z = 5.7
Martin, Crystal L.; Sawicki, Marcin; Dressler, Alan +2 more
We present NICMOS J 110 (rest-frame 1200-2100 Å) observations of the three z = 5.7 Lyα emitters discovered in the blind multislit spectroscopic survey by Martin et al. These images confirm the presence of the two sources that were previously only seen in spectroscopic observations. The third source, which is undetected in our J 110…
The Effect of Hot Coronal Electrons on Extreme-Ultraviolet Spectral Lines of He II Emitted by Solar Transition Region Plasmas
Doschek, G. A.; Feldman, U.; Ralchenko, Yu.
The cause of the lower intensities of extreme-ultraviolet (EUV) He II lines emitted by coronal hole (CH) plasmas compared with quiet Sun (QS) plasmas has been the subject of many studies dating back over half a century. In this paper, we study the effect of small amounts of "hot" electrons at coronal temperatures (Te = 1.4 × 106
The Formation of Spheroids in Early-type Spirals: Clues from Their Globular Clusters
Chandar, Rupali; Goudfrooij, Paul; Puzia, Thomas H. +1 more
We use deep Hubble Space Telescope images taken with the Advanced Camera for Surveys (ACS) in the F475W and F814W filters to investigate the globular cluster (GC) systems in four edge-on Sa spiral galaxies covering a factor of four in luminosity. The specific frequencies of the blue GCs in the galaxies in our sample fall in the range 0.34-0.84, si…