Search Publications
Scanning an Interplanetary Magnetic Cloud Using High-Energy Protons
Riihonen, E.; Torsti, J.; Kocharov, L. +2 more
We applied a numerical modeling of the solar energetic particle (SEP) event inside a magnetic cloud in the solar wind to analyze the 17-22 MeV proton flux anisotropy observed on 1998 May 2 with the Energetic and Relativistic Nuclei and Electron (ERNE) instrument on the Solar and Heliospheric Observatory (SOHO), when SOHO was inside a magnetic clou…
On the Effects of Dissipative Turbulence on the Narrow Emission-Line Ratios in Seyfert Galaxies
Kraemer, S. B.; Crenshaw, D. M.; Bottorff, M. C.
We present a photoionization model study of the effects of microturbulence and dissipative heating on emission lines for number and column densities, elemental abundances, and ionizations typical for the narrow emission line regions (NLRs) of Seyfert galaxies. Earlier studies of NLR spectra generally found good agreement between the observations a…
Revisiting the Soft X-Ray Excess Emission in Clusters of Galaxies Observed with XMM-Newton
Kaastra, J.; Bonamente, M.; Nevalainen, J.
We analyze XMM-Newton galaxy clusters Abell 1795, Abell S1101, Abell 1835, and MKW 3s in order to test whether their soft X-ray excess emission in the 0.2-0.5 keV band as reported by Kaastra et al. maintains after application of current knowledge of the XMM-Newton background and calibration. In this context, we examine the claim (Bregman & Llo…
A Multiwavelength Study of 1WGA J1346.5-6255: A New γ Cas Analog Unrelated to the Background Supernova Remnant G309.2-00.6
Safi-Harb, Samar; Lu, Fangjun; Chen, Yong +5 more
1WGA J1346.5-6255 is a ROSAT X-ray source found within the radio lobes of the supernova remnant (SNR) G309.2-00.6. It appears to coincide with the bright and early-type star HD 119682, in the galactic open cluster NGC 5281. Its radio morphology, consisting of two brightened and distorted arcs of emission on opposite sides of the 1WGA J1346.5-6255 …
Statistical Correlations between Parameters of Photospheric Magnetic Fields and Coronal Soft X-Ray Brightness
Jing, Ju; Wang, Haimin; Song, Hui +4 more
Using observations of more than 160 active regions, we investigate the relationship between the coronal X-ray brightness, LB, and five parameters derived from the photospheric magnetic fields. The coronal X-ray brightness and the magnetic measures were obtained from co-aligned SFD composite images from the Yohkoh SXT and full-disk magne…
Discovery of 13 Nova Candidates in M87
Ferguson, Henry C.; Livio, Mario; Sparks, William B. +2 more
We have made 13 positive identifications of near-ultraviolet (NUV) transient sources in the giant elliptical galaxy M87 using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). We give a representative sample of the light curves that we derive for these transients, and based on their characteristics we ident…
Soft and Hard X-Ray Excess Emission in Abell 3112 Observed with Chandra
Bonamente, Massimiliano; Lieu, Richard; Nevalainen, Jukka
Chandra ACIS-S observations of the galaxy cluster Abell 3112 feature the presence of an excess of X-ray emission above the contribution from the diffuse hot gas, which can be equally well modeled with an additional nonthermal power-law model or with a low-temperature thermal model of low metal abundance. We show that the excess emission cannot be …
High-Energy Protons Associated with Liftoff of a Coronal Mass Ejection
Riihonen, E.; Torsti, J.; Klein, K. -L. +7 more
Large solar energetic particle (SEP) events occur in association with fast coronal mass ejections (CMEs) and flares. We have studied in detail the rise phase of the SEP event of 1998 May 2 observed with the particle telescope ERNE aboard the Solar and Heliospheric Observatory (SOHO) spacecraft and ground-based neutron monitors. Using the ERNE data…
VLA H53α Observations of the Central Region of the Super Star Cluster Galaxy NGC 5253
Gómez, Y.; Rodríguez-Rico, C. A.; Goss, W. M. +1 more
We present observations in the H53α line and radio continuum at 43 GHz carried out with the VLA in the D configuration (2" angular resolution) toward the starburst galaxy NGC 5253. VLA archival data have been reprocessed to produce a uniform set of 2, 1.3, and 0.7 cm high angular (0.2''×0.1'') radio continuum images. The radi…
The Spitzer IRS Infrared Spectrum and Abundances of the Planetary Nebula IC 2448
Pottasch, S. R.; Bernard-Salas, J.; Roellig, T. L. +1 more
We present the mid-infrared spectrum of the planetary nebula IC 2448. In order to determine the chemical composition of the nebula, we use the infrared line fluxes from the Spitzer spectrum along with optical line fluxes from the literature and ultraviolet line fluxes from archival IUE spectra. We determine an extinction of CHβ=0.27 fro…