Search Publications
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…
A Chandra-HETG View of MCG +8-11-11
Nowak, M. A.; Murphy, K. D.
We present a spectral analysis of the 118 ks Chandra High Energy Transmission Gratings (HETG) observation of the X-ray bright Seyfert 1.5 galaxy MCG +8-11-11, in conjunction with 100 ks of archival Suzaku data, aimed at investigating the signatures of warm absorption and Compton reflection reported from previous Suzaku and XMM-Newton studies of th…
Stellar Encounter Driven Red-giant Star Mass Loss in Globular Clusters
Chung, Chul; Pasquato, Mario; Lee, Young-Wook +5 more
Globular cluster (GC) color-magnitude diagrams (CMDs) are reasonably well understood in terms of standard stellar evolution. However, there are still some open issues, such as fully accounting for the horizontal branch (HB) morphology in terms of chemical and dynamical parameters. Mass loss on the red giant branch (RGB) shapes the mass distributio…
The Temperature of Quiescent Streamers during Solar Cycles 23 and 24
Landi, E.; Testa, P.
Recent in-situ determinations of the temporal evolution of the charge state distribution in the fast and slow solar wind have shown a general decrease in the degree of ionization of all the elements in the solar wind along solar cycles 23 and 24. Such a decrease has been interpreted as a cooling of the solar corona which occurred during the declin…