Search Publications
Comparison of GONG and MDI: Sound-Speed Anomalies beneath Two Active Regions
Thompson, M. J.; Rajaguru, S. P.; Hughes, S. J.
Travel times of acoustic waves are calculated from Dopplergrams of solar oscillations obtained using the Global Oscillation Network Group (GONG) ground-based network and the Michelson Doppler Imager (MDI) instrument on board the SOHO satellite. These travel times are inverted using a standard ray approximation to ascertain the sound-speed anomalie…
Modeling the Energy Budget of Solar Wind Minor Ions: Implications for Temperatures and Abundances
Lie-Svendsen, Øystein; Esser, Ruth
The outflow of oxygen and silicon ions in the solar wind has been studied using a model that extends from the chromosphere into interplanetary space, with emphasis on understanding the energy budget of the minor ions. The model solves coupled gyrotropic transport equations, which account for temperature anisotropies and heat conduction, for all ch…
Mass Flows in a Disappearing Sunspot Plume
Brosius, Jeffrey W.
We observed a large sunspot in NOAA Active Region 9535 on 2001 July 12, 15, 17, and 19 with three instruments (CDS, EIT, and MDI) on board SOHO. EUV emission lines of O IV (formed at logarithmic temperature of 5.2), O V (5.4), Ne IV (5.2), Ne V (5.5), Ne VI (5.6), Ne VII (5.7), and Ca X (5.9) revealed a large bright plume within the sunspot penumb…
The Ultraluminous X-Ray Source X-37 Is a Background Quasar in the Antennae Galaxies
Hayward, T. L.; Brandl, B. R.; Eikenberry, S. S. +8 more
In this Letter we report that a bright, X-ray source in the Antennae galaxies (NGC 4038/9), previously identified as an ultraluminous X-ray source (ULX), is in fact a background quasar. We identify an isolated infrared and optical counterpart within 0.3" +/- 0.5" of the X-ray source X-37. After acquiring an optical spectrum of its counterpart, we …
The Interaction of the Galactic Center Arches Cluster and the Thermal Filaments
Rubin, Robert H.; Colgan, Sean W. J.; Simpson, Janet P. +1 more
We present Infrared Space Observatory (ISO) measurements of the far-infrared (FIR) fine-structure lines [S IV] (10.5 µm), [S III] (33.5 µm), [O III] (51.8 and 88.4 µm), [N III] (57.3 µm), [N II] (121.9 µm), [O I] (63.2 and 145.5 µm), and [C II] (157.7 µm) at five positions on the thermal ``Arched'' Filamen…
The SDSS/XMM-Newton Quasar Sample. I. First Results
Elvis, Martin; Risaliti, Guido
We have searched in the XMM-Newton public archive for quasars in the Sloan Digital Sky Survey First Data Release and found 55 lying in the field of an XMM-Newton observation with exposure times >20 ks (as of 2004 August). The 35 quasars that yielded good X-ray spectra span redshifts from 0.5 to 2.5. The large collecting area of XMM-Newton allow…
A Deep Search with the Hubble Space Telescope for Late-Time Supernova Signatures in the Hosts of XRF 011030 and XRF 020427
Wood-Vasey, W. Michael; Ramirez-Ruiz, Enrico; Tanvir, Nial +16 more
X-ray flashes (XRFs) are, like gamma-ray bursts (GRBs), thought to signal the collapse of massive stars in distant galaxies. Many models posit that the isotropic equivalent energies of XRFs are lower than those for GRBs, such that they are visible from a reduced range of distances when compared with GRBs. Here we present the results of two-epoch H…
Discovery of Optical Emission in the Hot Spots of Three 3CR Quasars: High-Energy Particle Acceleration in Powerful Radio Hot Spots
Cheung, C. C.; Wardle, J. F. C.; Chen, Tingdong
Archival Hubble Space Telescope WFPC2 images were used to search for optical emission associated with the radio jets of a number of luminous quasars. From this search, we report new optical hot spot detections in the well-known blazar 3C 454.3 and the lobe-dominated quasars 3C 275.1 and 3C 336. We also find optical emission in the vicinity of the …
Fourier-Resolved Spectroscopy of the XMM-Newton Observations of MCG -06-30-15
Papadakis, I. E.; Akylas, A.; Kazanas, Demosthenes
We study the frequency-resolved spectra of the Seyfert galaxy MCG -06-30-15 obtained during two recent XMM-Newton observations. Splitting the Fourier spectra in soft (E<~2 keV) and hard (E>~2 keV) bands, we find that the soft band has a variability amplitude larger than the hard one on timescales longer than 10 ks, while the opposite is true…
X-Rays from Cepheus A East and West
Tsuboi, Yohko; Pravdo, Steven H.
We report the discovery of X-rays from both components of Cepheus A, East and West, with the XMM-Newton observatory. HH 168 joins the ranks of other energetic Herbig-Haro objects that are sources of T>=106 K X-ray emission. The effective temperature of HH 168 is T=5.8+3.5-2.3×106 K, and its unabsorbed…