Search Publications
Multiheight Properties of Moving Magnetic Features
Choudhary, Debi Prasad; Balasubramaniam, K. S.
We report on spectropolarimetric and dynamical properties of a moving magnetic feature (MMF) around a disk-center sunspot observed using photospheric (Fe I λλ6301.5 and 6302.5) and lower chromospheric (Mg b2 λ5172.7) lines. We find that there are 33% fewer MMFs at the lower chromosphere compared to the photosphere, implying a sophistica…
FUSE Observations of a Full Orbit of Hercules X-1: Signatures of Disk, Star, and Wind
Raymond, John C.; Vrtilek, Saeqa Dil; Still, Martin +1 more
We observed an entire 1.7 day orbit of the X-ray binary Hercules X-1 with the Far Ultraviolet Spectroscopic Explorer (FUSE). Changes in the O VI λλ1032, 1037 line profiles through eclipse ingress and egress indicate a Keplerian accretion disk spinning prograde with the orbit. These observations may show the first double-peaked accretion disk line …
Witnessing the Formation of a Galaxy Cluster at z = 0.485: Optical and X-Ray Properties of RX J1117.4+0743 ([VMF 98] 097)
Cypriano, E. S.; Ramirez, A.; Carrasco, E. R. +4 more
We present a multiwavelength study of the poor cluster RX J1117.4+0743 ([VMF 98] 097) at z=0.485, based on GMOS/Gemini South g' and r' photometry and spectroscopy, and XMM-Newton observations. We examine its nature and surroundings by analyzing the projected galaxy distribution, the galaxy velocity distribution, the weak-lensing mass reconstructio…
Molecular and Atomic Excitation Stratification in the Outflow of the Planetary Nebula M27
France, Kevin; Feldman, Paul D.; Andersson, B. -G. +5 more
High-resolution spectroscopy with FUSE and HST STIS of atomic and molecular velocity stratification in the nebular outflow of M27 challenge models of the abundance kinematics in planetary nebulae. The simple picture of a very high speed (~1000 km s-1), high-ionization, radiation-driven stellar wind surrounded by a slower (~10 km s-…
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…