Search Publications
Properties of Remote Flare Ribbons Associated with Coronal Mass Ejections
Wang, Haimin
To understand the large-scale structure of flares and coronal mass ejections, we studied the motion and properties of remote flare ribbons of three major events: 2003 May 27 X1.3, 2000 November 24 X1.8, and 2000 November 25 X1.9 flares. The remote ribbons are in addition to the typical two-ribbon pairs in the flare cores. We found two common prope…
Nanodiamond Dust and the Far-Ultraviolet Quasar Break
Krongold, Yair; Morisset, Christophe; Binette, Luc +5 more
We explore the possibility that the steepening observed shortward of 1000 Å in the energy distribution of quasars may result from absorption by dust, being either intrinsic to the quasar environment or intergalactic. We find that a dust extinction curve consisting of nanodiamonds, composed of terrestrial cubic diamonds or with surface impurities a…
The Low Quiescent X-Ray Luminosity of the Transient X-Ray Burster EXO 1747-214
Kaaret, Philip; Gelino, Dawn M.; Tomsick, John A.
We report on X-ray and optical observations of the X-ray burster EXO 1747-214. This source is an X-ray transient, and its only known outburst was observed in 1984-1985 by the EXOSAT satellite. We reanalyzed the EXOSAT data to derive the source position, column density, and a distance upper limit using its peak X-ray burst flux. We observed the EXO…
Far-Ultraviolet Spectroscopy of the Dwarf Novae SS Cygni and WX Hydri in Quiescence
Blair, William P.; Kallman, Timothy R.; Long, Knox S. +3 more
We present time-resolved FUV spectra of the dwarf novae SS Cyg and WX Hyi in quiescence from observations using the Hopkins Ultraviolet Telescope on the Astro-1 and Astro-2 space shuttle missions and the Goddard High Resolution Spectrograph on the Hubble Space Telescope. Both dwarf novae are characterized by blue continua that extend to the Lyman …
Bulk Comptonization of the Cosmic Microwave Background by Extragalactic Jets as a Probe of Their Matter Content
Georganopoulos, Markos; Kazanas, Demosthenes; Perlman, Eric +1 more
We propose a method for estimating the composition, i.e., the relative amounts of leptons and protons, of extragalactic jets that exhibit X-ray-bright knots in their kiloparsec-scale jets. The method relies on measuring, or setting upper limits on, the component of the cosmic microwave background (CMB) radiation that is bulk Comptonized (BC) by co…
A slow coronal mass ejection with rising X-ray source
Mandrini, C. H.; van Driel-Gesztelyi, L.; Harra, L. K. +2 more
An eruptive event, which occurred on 16th April 2002, is discussed. Using images from the Transition Region and Coronal Explorer (TRACE) at 195 Å, we observe a lifting flux rope which gives rise to a slow coronal mass ejection (CME). There are supporting velocity observations from the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliosph…
The X-ray spectrum of NGC 7213 and the Seyfert-LINER connection
Page, M. J.; Branduardi-Raymont, G.; Soria, R. +3 more
We present an XMM-Newton observation of the Seyfert-LINER (low-ionization nuclear emission-line region) galaxy NGC 7213. The RGS soft X-ray spectrum is well fitted with a power law plus soft X-ray collisionally ionized thermal plasma (kT= 0.18+0.03-0.01 keV). We confirm the presence of FeI, FeXXV and FeXXVI Kα emission in the…
Search for 17 µm H2 Pure Rotational Emission from Circumstellar Disks
Onaka, T.; Kataza, H.; Sako, S. +5 more
We report the negative detection of the S(1) pure rotational line emission of molecular hydrogen at 17.035 µm for four young stars, HD 163296, MWC 863, CQ Tau, and LkCa 15, for which Infrared Space Observatory (ISO) observations detected the S(1) emission, with the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the 8.2 m Subaru Tele…
Two Sympathetic Homologous CMEs on 2002 May 22
Ding, Ming-De; Fang, Cheng; Cheng, Jian-Xia +1 more
Sympathetic coronal mass ejections (CMEs) usually occur in different active regions connected by interconnecting magnetic loops, while homologous CMEs occur within the same active region with an almost the same background magnetic field, and so are similar in shapes. Two sympathetic CMEs erupted within 3 hours on 2002 May 22, originating from the …
XMM-Newton surveys of the Canada-France Redshift Survey Fields - III. The environments of X-ray selected active galactic nuclei at 0.4 < z < 0.6
Lilly, S.; McCracken, H. J.; Eales, S. A. +3 more
The environmental properties of a sample of 31 hard X-ray selected active galactic nuclei (AGN) are investigated, from scales of 500 kpc down to 30 kpc, and are compared to a control sample of inactive galaxies. All the AGN lie in the redshift range 0.4 < z < 0.6. The accretion luminosity density of the Universe peaks close to this redshift …