Search Publications
XMM-Newton/Sloan Digital Sky Survey: Star Formation Efficiency in Galaxy Clusters and Constraints on the Matter-density Parameter
Reiprich, Thomas H.; Schneider, Peter; Zhang, Yu-Ying +1 more
It is believed that the global baryon content of clusters of galaxies is representative of the matter distribution of the universe, and can, therefore, be used to reliably determine the matter-density parameter Ωm. This assumption is challenged by the growing evidence from optical and X-ray observations that the total baryon mass fracti…
X-Ray and Ultraviolet Emission from the Recurrent Nova RS Ophiuchi in Quiescence: Signatures of Accretion and Shocked Gas
Nelson, T.; Mukai, K.; Sokoloski, J. L. +2 more
RS Ophiuchi is a recurrent nova system that experiences outbursts every ~20 years, implying accretion at a high rate onto a massive white dwarf. However, previous X-ray observations of the system in quiescence have detected only faint emission that is difficult to reconcile with the high accretion rate (>2 × 10-8 M sun yr<…
Hubble Space Telescope Observations of Field Ultracool Dwarfs at High Galactic Latitude
Ryan, R. E.; Yan, L.; Fan, X. +8 more
We present a sample of 17 newly discovered ultracool dwarf candidates later than ~M8, drawn from 231.90 arcmin2 of Hubble Space Telescope Wide Field Camera 3 infrared imaging. By comparing the observed number counts for 17.5 <= J 125 <= 25.5 AB mag to an exponential disk model, we estimate a vertical scale height of z <…
The Old Environment of the Faint Calcium-rich Supernova SN 2005cz
Leonard, Douglas C.; Neill, James D.; James, Phil A. +5 more
The supernova SN 2005cz has recently attracted some attention due to the fact that it was spectroscopically similar to type Ib supernovae (SNe Ib), a class that is presumed to result from the core collapse of massive stars, yet it occurred in an elliptical galaxy, where one expects very few massive stars to exist. Two explanations for this remarka…
Pre-flare Activity and Magnetic Reconnection during the Evolutionary Stages of Energy Release in a Solar Eruptive Flare
Joshi, Bhuwan; Veronig, Astrid M.; Tiwari, Sanjiv Kumar +3 more
In this paper, we present a multi-wavelength analysis of an eruptive white-light M3.2 flare that occurred in active region NOAA 10486 on 2003 November 1. The excellent set of high-resolution observations made by RHESSI and the TRACE provides clear evidence of significant pre-flare activities for ~9 minutes in the form of an initiation phase observ…
Fundamental Properties of the Highly Ionized Plasmas in the Milky Way
Savage, B. D.; Lehner, N.; Howk, J. C. +1 more
The cooling transition temperature gas in the interstellar medium (ISM), traced by the high ions, Si IV, C IV, N V, and O VI, helps to constrain the flow of energy from the hot ISM with T>106 K to the warm ISM with T < 2 × 104 K. We investigate the properties of this gas along the lines of sight to 38 stars in the Milky…
Widespread Nanoflare Variability Detected with Hinode/X-Ray Telescope in a Solar Active Region
Reale, Fabio; Tsuneta, Saku; Miceli, Marco +3 more
It is generally agreed that small impulsive energy bursts called nanoflares are responsible for at least some of the Sun's hot corona, but whether they are the explanation for most of the multimillion-degree plasma has been a matter of ongoing debate. We present here evidence that nanoflares are widespread in an active region observed by the X-Ray…
The ACS Survey of Galactic Globular Clusters. XI. The Three-dimensional Orientation of the Sagittarius Dwarf Spheroidal Galaxy and Its Globular Clusters
Anderson, Jay; Dotter, Aaron; Law, David R. +13 more
We use observations from the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) study of Galactic globular clusters to investigate the spatial distribution of the inner regions of the disrupting Sagittarius dwarf spheroidal galaxy (Sgr). We combine previously published analyses of four Sgr member clusters located near or in the Sgr core …
Discovery of a Super-Li-rich Turnoff Star in the Metal-poor Globular Cluster NGC 6397
Lind, Karin; Rich, R. Michael; Koch, Andreas
We report on the discovery of a super-Li-rich turnoff (TO) star in the old (12 Gyr), metal-poor ([Fe/H] = -2.1 dex) globular cluster (GC) NGC 6397, based on high-resolution MIKE/Magellan spectra. This star shows an unusually high lithium abundance of A(Li)NLTE = 4.03 ± 0.06 ± 0.14 dex (or, 4.21, accounting for possible contamination fro…
Coronal Seismology Using EIT Waves: Estimation of the Coronal Magnetic Field Strength in the Quiet Sun
Zhukov, A. N.; Dolla, L.; Rodriguez, L. +1 more
Coronal EIT waves have been observed for many years. The nature of EIT waves is still contentious, however, there is strong evidence that some of them might be fast magnetosonic waves, or at least have a fast magnetosonic wave component. The fast magnetosonic wave speed is formed from two components; the Alfvén speed (magnetic) and the sound speed…