Search Publications
The Long-Term Radiative Evolution of Anomalous X-Ray Pulsar 1E 2259+586 After Its 2002 Outburst
Zhu, Weiwei; Kaspi, Victoria M.; Woods, Peter M. +3 more
We present an analysis of five XMM-Newton observations of the anomalous X-ray pulsar (AXP) 1E 2259+586 taken in 2004 and 2005 during its relaxation following its 2002 outburst. We compare these data with those of five previous XMM-Newton observations taken in 2002 and 2003, and find the observed flux decay is well described by a power law of index…
A Statistical Study on Rotating Sunspots: Polarities, Rotation Directions, and Helicities
Yan, X. L.; Qu, Z. Q.; Xu, C. L.
Observations of white-light images from SOHO MDI, TRACE, Hinode, SOHO MDI magnetograms, and Hinode SP vector magnetograms show sufficient samples of rotating sunspots on the solar photosphere for a statistical study. During the period from 1996 December to 2007 December, after individually checking the active regions in detail, we found 182 measur…
Magnetic Flux Loss and Flux Transport in a Decaying Active Region
Kubo, M.; Lites, B. W.; Ichimoto, K. +1 more
We estimate the temporal change of magnetic flux normal to the solar surface in a decaying active region by using a time series of the spatial distribution of vector magnetic fields in the photosphere. The vector magnetic fields are derived from full spectropolarimetric measurements with the Solar Optical Telescope aboard Hinode. We compare a magn…
Small-Scale Behavior of the Physical Conditions and the Abundance Discrepancy in the Orion Nebula
Mesa-Delgado, Adal; Esteban, César; García-Rojas, Jorge
We present the results of long-slit spectroscopy, in several positions, of the Orion Nebula. Our goal is to study the spatial distributions of a large number of nebular quantities, including line fluxes, physical conditions, and ionic abundances, at a spatial resolution of about 1''. In particular, we have compared the O++ abundance det…
Probing the Nature of the Vela X Cocoon
Slane, Patrick O.; LaMassa, Stephanie M.; de Jager, Okkie C.
Vela X is a pulsar wind nebula (PWN) associated with the active pulsar B0833-45 and contained within the Vela supernova remnant (SNR). A collimated X-ray filament ("cocoon") extends south-southwest from the pulsar to the center of Vela X. VLA observations uncovered radio emission coincident with the eastern edge of the cocoon, and H.E.S.S. has det…
A Broadband Microwave Burst Produced by Electron Beams
Melnikov, V. F.; Fleishman, G. D.; Huang, G. -L. +1 more
The theoretical and experimental study of fast electron beams attracts much attention in astrophysics and the laboratory. In the case of solar flares, the problem of reliable beam detection and diagnostics is of exceptional importance. This paper explores the fact that electron beams moving obliquely to the magnetic field or along the field with s…
Low-Level Nuclear Activity in Nearby Spiral Galaxies
Fiore, Fabrizio; Mathur, Smita; Ferrarese, Laura +1 more
We are conducting a search for supermassive black holes (SMBHs) with masses below ~107 M⊙ by looking for signs of extremely low-level nuclear activity in nearby galaxies that are not known to be AGNs. Our survey has the following characteristics: (1) X-ray selection using the Chandra X-Ray Observatory, since X-rays are a ubiq…
VLT Spectroscopy of Globular Clusters in Low Surface Brightness Dwarf Galaxies
Puzia, Thomas H.; Sharina, Margarita E.
We present VLT/FORS2 spectroscopic observations of globular clusters (GCs) in five low surface brightness dwarf galaxies: KK 211 and KK 221, both dwarf spheroidal satellites (dSph) of NGC 5128; dSph KK 84 located close to the isolated S0 galaxy NGC 3115; and two isolated dwarf irregular (dIrr) galaxies, UGC 3755 and ESO 490-17. Our sample is selec…
Self-Regulated Fueling of Galaxy Centers: Evidence for Star Formation Feedback in IC 342's Nucleus
Meier, David S.; Böker, Torsten; Calzetti, Daniela +1 more
Using new, high-resolution interferometric observations of the CO and HCN molecules, we directly compare the molecular and ionized components of the interstellar medium in the center of the nearby spiral galaxy IC 342, on spatial scales of ≈10 pc. The morphology of the tracers suggests that the molecular gas flow caused by a large-scale stellar ba…
The Solar Magnetic Field and Coronal Dynamics of the Eruption on 2007 May 19
Luhmann, J. G.; Li, Y.; Lynch, B. J. +5 more
The solar eruption on 2007 May 19, from AR 10956 near solar disk center, consisted of a B9.5 flare (12:48 UT), a filament eruption, an EUV dimming, a coronal wave, and a multifront CME. The eruption was observed by the twin STEREO spacecraft at a separation angle of 8.5°. We report analysis of the source region photospheric magnetic field and its …