Search Publications
Stellar Populations in NGC 4038/39 (the Antennae): Exploring a Galaxy Merger Pixel by Pixel
Pogge, Richard W.; Frogel, Jay A.; Kassin, Susan A. +2 more
We present deep, photometrically calibrated BVRJHK images of the nearby interacting galaxy pair NGC 4038/39 (the Antennae). Color maps of the images are derived, and those using the B, V, and K bands are analyzed with techniques developed for examining the colors of stars. From these data we derive pixel-by-pixel maps of the distributions of stell…
A spatially resolved limb flare on Algol B observed with XMM-Newton
Schmitt, J. H. M. M.; Ness, J. -U.; Franco, G.
We report XMM-Newton observations of the eclipsing binary Algol A (B8V) and B (K2III). The XMM-Newton data cover the phase interval 0.35-0.58, i.e., specifically the time of optical secondary minimum, when the X-ray dark B-type star occults a major fraction of the X-ray bright K-type star. During the eclipse a flare was observed with complete ligh…
A Probable Dwarf Nova Outburst in the Core of the Globular Cluster M22
Anderson, Jay; Cool, Adrienne M.; King, Ivan R.
We reexamine an event that was previously reported by Sahu et al. as a microlensing event of a Galactic bulge star by a star of M22. We find strong evidence that the event was actually a dwarf nova outburst of a cataclysmic variable in the cluster. The primary evidence consists of the star's proper motion, Hα emission, X-ray luminosity, and variab…
Observations of Giant Outbursts from Cygnus X-1
Cline, T.; Hurley, K.; Golenetskii, S. +5 more
We present interplanetary network localization, spectral, and time history information for seven episodes of exceptionally intense gamma-ray emission from Cyg X-1. The outbursts occurred between 1995 and 2003, with durations up to ~28,000 s. The observed 15-300 keV peak fluxes and fluences reached 3×10-7 ergs cm-2 s-1
Keck Spectroscopy of Globular Clusters in the Elliptical Galaxy NGC 3610
Brodie, Jean P.; Seitzer, Patrick; Strader, Jay +2 more
We present low-resolution Keck spectra of nine candidate globular clusters in the possible merger-remnant elliptical galaxy NGC 3610. Eight of the objects appear to be bona fide globular clusters of NGC 3610. We find that two of the clusters belong to an old metal-poor population, five to an old metal-rich population, and only one to an intermedia…
Small-scale structure of the galactic cirrus emission
del Burgo, C.; Ábrahám, P.; Lemke, D. +4 more
We examined the Fourier power spectrum characteristics of cirrus structures in 13 sky fields with faint to bright cirrus emission observed with ISOPHOT in the 90-200 mu m wavelength range in order to study variations of the spectral index alpha . We found that alpha varies from field to field with -5.3 le alpha le -2.1. It depends on the absolute …
Properties of Solar Plasmas near Solar Maximum above Two Quiet Regions at Distances of 1.02-1.34 Rsolar
Landi, E.; Feldman, U.
In the present work we have analyzed the spectra emitted by two quiet solar regions observed off the solar disk by the SUMER instrument on board the SOHO satellite. The two complete spectra were recorded when the SOHO north-south axis was rotated relative to the Sun north-south axis by ~=150° clockwise. As a result, the SUMER slit could be placed …
Signs of magnetic helicity in interplanetary coronal mass ejections and associated prominences: Case study
Hu, Qiang; Ruzmaikin, Alexander; Martin, Sara
We study the distribution of magnetic helicity in interplanetary coronal mass ejections (CMEs) separated into magnetic clouds and remnants of the prominence structures for three cases with identified remnants of prominences. The magnetic configurations of magnetic clouds and prominence remnants can satisfactorily be described by the flux rope appr…
The Earth's quasi-parallel bow shock: Review of observations and perspectives for Cluster
Wilkinson, William P.
Spacecraft crossings of the Earth's quasi-parallel bow shock under typical high Mach number conditions are characterized by the presence of large-amplitude, compressive, low-frequency magnetic pulsations. Thus, instead of the fairly abrupt jump from upstream to downstream states one associates with their quasi-perpendicular counterparts, quasi-par…
Properties of fast magnetosonic shocklets at the bow shock
Lavraud, B.; Buchert, S.; Stasiewicz, K. +3 more
We present detailed properties of fast magnetosonic shocklets (1000 km in size and amplitude of 10 times the background B-field values) observed in natural unbounded collisionless plasma by a fleet of four Cluster spacecraft at the quasi-parallel bow shock. We provide for the first time details of the internal structure of shocklets which have mag…