Search Publications
Spatiotemporal Organization of Energy Release Events in the Quiet Solar Corona
Davila, Joseph M.; Uritsky, Vadim M.
Using data from the STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. T…
Comparison of Prestellar Core Elongations and Large-scale Molecular Cloud Structures in the Lupus I Region
Ward-Thompson, Derek; Fissel, Laura M.; Savini, Giorgio +28 more
Turbulence and magnetic fields are expected to be important for regulating molecular cloud formation and evolution. However, their effects on sub-parsec to 100 parsec scales, leading to the formation of starless cores, are not well understood. We investigate the prestellar core structure morphologies obtained from analysis of the Herschel-SPIRE 35…
Are the Faint Structures Ahead of Solar Coronal Mass Ejections Real Signatures of Driven Shocks?
Moon, Y. -J.; Lee, Kyoung-Sun; Kim, Sujin +3 more
Recently, several studies have assumed that the faint structures ahead of coronal mass ejections (CMEs) are caused by CME-driven shocks. In this study, we have conducted a statistical investigation to determine whether or not the appearance of such faint structures depends on CME speeds. For this purpose, we use 127 Solar and Heliospheric Observat…
A 30 kpc Chain of "Beads on a String" Star Formation between Two Merging Early Type Galaxies in the Core of a Strong-lensing Galaxy Cluster
Baum, Stefi A.; O'Dea, Christopher P.; Rigby, Jane R. +10 more
New Hubble Space Telescope ultraviolet and optical imaging of the strong-lensing galaxy cluster SDSS J1531+3414 (z = 0.335) reveals two centrally dominant elliptical galaxies participating in an ongoing major merger. The interaction is at least somewhat rich in cool gas, as the merger is associated with a complex network of 19 massive supercluster…
Merger Signatures in the Galaxy Cluster A98
Paterno-Mahler, R.; Johnson, R. E.; Bulbul, E. +5 more
We present results from Chandra and XMM-Newton observations of Abell 98 (A98), a galaxy cluster with three major components: a relatively bright subcluster to the north (A98N), a disturbed subcluster to the south (A98S), and a fainter subcluster to the far south (A98SS). We find evidence for surface brightness and temperature asymmetries in A98N c…
Relaxation Processes in Solar Wind Turbulence
Carbone, V.; Gurgiolo, C.; Goldstein, M. L. +1 more
Based on global conservation principles, magnetohydrodynamic (MHD) relaxation theory predicts the existence of several equilibria, such as the Taylor state or global dynamic alignment. These states are generally viewed as very long-time and large-scale equilibria, which emerge only after the termination of the turbulent cascade. As suggested by hy…
An HST/COS Observation of Broad Lyα Emission and Associated Absorption Lines of the BL Lacertae Object H 2356-309
Shull, J. Michael; Danforth, Charles W.; Stocke, John T. +4 more
Weak spectral features in BL Lacertae objects (BL Lacs) often provide a unique opportunity to probe the inner region of this rare type of active galactic nucleus. We present a Hubble Space Telescope/Cosmic Origins Spectrograph observation of the BL Lac H 2356-309. A weak Lyα emission line was detected. This is the fourth detection of a weak Lyα em…
A Transient Supergiant X-Ray Binary in IC 10: An Extragalactic SFXT?
Cappallo, Rigel; Laycock, Silas; Oram, Kathleen +1 more
We report the discovery of a large amplitude (factor of ~100) X-ray transient (IC 10 X-2, CXOU J002020.99+591758.6) in the nearby dwarf starburst galaxy IC 10 during our Chandra monitoring project. Based on the X-ray timing and spectral properties, and an optical counterpart observed with Gemini, the system is a high-mass X-ray binary consisting o…
A Detailed Analysis of the High Resolution X-Ray Spectra of NGC 3516: Variability of the Ionized Absorbers
Nicastro, F.; Krongold, Y.; Longinotti, A. L. +3 more
The 1.5 Seyfert galaxy NGC 3516 presents a strong time variability in X-rays. We re-analyzed the nine observations performed in 2006 October by XMM-Newton and Chandra in the 0.3 to 10 keV energy band. An acceptable model was found for the XMM-Newton data fitting the EPIC-PN and RGS spectra simultaneously; later, this model was successfully applied…
Stochasticity and Persistence of Solar Coronal Mass Ejections
Carbone, V.; Antonucci, E.; Telloni, D. +1 more
The study of the statistical properties of coronal mass ejections (CMEs) reveals that their properties depend on the period of solar activity. In particular, when investigating the origin of the waiting time distribution between CMEs, a significant departure from a Poisson process during periods of high solar activity has been found, thus suggesti…