Search Publications
Exploring the Origin and Fate of the Magellanic Stream with Ultraviolet and Optical Absorption
Richter, Philipp; Sembach, Kenneth R.; Savage, Blair D. +3 more
We present an analysis of ionization and metal enrichment in the Magellanic Stream (MS), the nearest gaseous tidal stream, using Hubble Space Telescope/STIS and FUSE ultraviolet spectroscopy of two background active galactic nuclei. The targets are NGC 7469, lying directly behind the MS with log N(H I)MS = 18.63 ± 0.03(stat) ± 0.08(syst…
The Importance of Nebular Continuum and Line Emission in Observations of Young Massive Star Clusters
Nidever, David L.; Johnson, Kelsey E.; Reines, Amy E. +1 more
In this spectroscopic study of infant massive star clusters, we find that continuum emission from ionized gas rivals the stellar luminosity at optical wavelengths. In addition, we find that nebular line emission is significant in many commonly used broadband Hubble Space Telescope (HST) filters including the F814W I-band, the F555W V-band, and the…
Quasi-Periodic Pulsations in the Gamma-Ray Emission of a Solar Flare
Foullon, C.; Nakariakov, V. M.; Myagkova, I. N. +1 more
Quasi-periodic pulsations (QPPs) of gamma-ray emission with a period of about 40 s are found in a single loop X-class solar flare on 2005 January 1 at photon energies up to 2-6 MeV with the SOlar Neutrons and Gamma-rays (SONG) experiment aboard the CORONAS-F mission. The oscillations are also found to be present in the microwave emission detected …
A Reconnecting Current Sheet Imaged in a Solar Flare
Liu, Chang; Wang, Haimin; Stenborg, Guillermo +3 more
Magnetic reconnection changes the magnetic field topology and powers explosive events in astrophysical, space, and laboratory plasmas. For flares and coronal mass ejections (CMEs) in the solar atmosphere, the standard model predicts the presence of a reconnecting current sheet, which has been the subject of considerable theoretical and numerical m…
The Mass Structure of the Galaxy Cluster Cl0024+1654 from a Full Lensing Analysis of Joint Subaru and ACS/NIC3 Observations
Broadhurst, Tom; Zitrin, Adi; Umetsu, Keiichi +4 more
We derive an accurate mass distribution of the rich galaxy cluster Cl0024+1654 (z = 0.395) based on deep Subaru BR c z' imaging and our recent comprehensive strong-lensing analysis of Hubble Space Telescope/Advanced Camera for Surveys/NIC3 observations. We obtain the weak-lensing distortion and magnification of undiluted samples of red …
Internal Dynamics and Membership of the NGC 3603 Young Cluster from Microarcsecond Astrometry
Henning, Thomas; Da Rio, Nicola; Gennaro, Mario +5 more
We have analyzed two epochs of HST/WFPC2 observations of the young Galactic starburst cluster in NGC 3603 with the aim to study its internal dynamics and stellar population. Relative proper motions measured over 10.15 yrs of more than 800 stars enable us to distinguish cluster members from field stars. The best-fitting isochrone yields A V
The X-ray Energy Dependence of the Relation Between Optical and X-ray Emission in Quasars
Elvis, M.; Risaliti, G.; Young, M.
We develop a new approach to the well-studied anti-correlation between the optical-to-X-ray spectral index, αox, and the monochromatic optical luminosity, l opt. By cross-correlating the Sloan Digital Sky Survey DR5 quasar catalog with the XMM-Newton archive, we create a sample of 327 quasars with X-ray signal-to-noise ratio …
Highest Resolution Observations of the Quietest Sun
Cao, Wenda; Yurchyshyn, Vasyl; Chae, Jongchul +4 more
Highest resolution observations made with the new 1.6 m aperture solar telescope in Big Bear Solar Observatory during this time of historic inactivity on the Sun reveal new insights into the small-scale dynamics of the Sun's photosphere. The telescope's unprecedented resolution enabled us to observe that the smallest scale photospheric magnetic fi…
Morphologies of Local Lyman Break Galaxy Analogs. II. A Comparison with Galaxies at z ~= 2-4 in ACS and WFC3 Images of the Hubble Ultra Deep Field
Rich, R. M.; Heckman, T. M.; Schiminovich, D. +4 more
Previous work has shown that Lyman break galaxies (LBGs) display a range in structures (from single and compact to more clumpy and extended) that is different from typical local star-forming galaxies. Recently, we have introduced a sample of rare, nearby (z < 0.3) starburst galaxies that appear to be good analogs of LBGs. These "Lyman break ana…
First Complete Determination of Plasma Physical Parameters Across a Coronal Mass Ejection-driven Shock
Bemporad, A.; Mancuso, S.
We report on the study of a fast coronal mass ejection (CME)-driven shock associated with the solar eruption of 2002 March 22. This event was observed in the intermediate corona both in white light and the extreme ultraviolet (EUV) by the LASCO and UVCS instruments on board the Solar and Heliospheric Observatory, as well as in metric and decametri…