Search Publications
The Spiros imaging software for the Integral SPI spectrometer
Connell, P.; Skinner, G.
A key tool in the package of software available for the analysis of data from the SPI spectrometer of Integral is the SPIROS system developed at the University of Birmingham. Although intended primarily for the analysis of point sources and for the extraction of spectral information, SPIROS has many additional capabilities. The software is describ…
The Dust in Lyman Break Galaxies
Gordon, Karl D.; Witt, Adolf N.; Vijh, Uma P.
We present our analysis of UV attenuation by internal dust of a large sample (N=906 galaxies) of Lyman break galaxies (LBGs). Using spectral energy distributions (SEDs) from the PÉGASE galaxy spectral evolution model, we apply dust attenuation corrections to the G-R colors, using the Witt & Gordon models for radiative transfer in dusty galacti…
Delayed Soft X-Ray Emission Lines in the Afterglow of GRB 030227
Watson, D.; Reeves, J. N.; Pedersen, K. +2 more
Strong delayed X-ray line emission is detected in the afterglow of gamma-ray burst GRB 030227, appearing near the end of the XMM-Newton observation, nearly 20 hr after the burst. The observed flux in the lines, not simply the equivalent width, sharply increases from an undetectable level (<1.7×10-14 ergs cm-2 s-1
Deep Hubble Space Telescope Imaging of Sextans A. II. Cepheids and Distance
Dolphin, Andrew E.; Skillman, Evan D.; Saha, A. +6 more
We have identified 82 short-period variable stars in Sextans A from deep Wide Field Planetary Camera 2 observations. All the periodic variables appear to be short-period Cepheids, with periods as small as 0.8 days for fundamental mode Cepheids and 0.5 days for first-overtone Cepheids. These objects have been used, along with measurements of the re…
An extragalactic supernebula confined by gravity
Larkin, J. E.; Turner, J. L.; Beck, S. C. +3 more
Little is known about the origins of globular clusters, which contain hundreds of thousands of stars in a volume only a few light years across. Radiation pressure and winds from luminous young stars should disperse the star-forming gas and disrupt the formation of the cluster. Globular clusters in our Galaxy cannot provide answers; they are billio…
The Solar Wind and Its Magnetic Sources at Sunspot Maximum
Sheeley, N. R., Jr.; Wang, Y. -M.
We use in situ measurements from the Advanced Composition Explorer and magnetograph data from the National Solar Observatory to relate the properties of the solar wind during 1998-2002 to its source region magnetic fields. The great bulk of the solar maximum wind is characterized by low proton speeds (vp~420 km s-1) and high …
The interferometric diameter and internal structure of Sirius A
Bordé, P.; Morel, P.; Kervella, P. +2 more
The interferometric observations of dwarf stars in the solar neighbourhood, combined with HIPPARCOS parallaxes provide very precise values of their linear diameters. In this paper, we report the direct measurement of the angular diameter of the bright star Sirius A with the VINCI/VLTI instrument. We obtain a uniform disk angular diameter of theta_…
Consequences of proton and alpha anisotropies in the solar wind: Hybrid simulations
Goldstein, Bruce E.; Neugebauer, Marcia; Gary, S. Peter +3 more
Alfvén fluctuations propagating away from the Sun in the solar corona and solar wind transfer energy via cyclotron resonances to ions of successively larger charge-to-mass ratios. This can yield T⟂/T∥ > 1 for each ion species, where the subscripts refer to directions relative to the background magnetic field. If these anis…
A measure from line-of-sight magnetograms for prediction of coronal mass ejections
Falconer, D. A.; Moore, R. L.; Gary, G. A.
From a sample of 17 vector magnetograms of 12 bipolar active regions we have recently found (1) that a measure of the overall nonpotentiality (the overall twist and shear in the magnetic field) of an active region is given by the strong shear length LSS, the length of the portion of the main neutral line on which the observed transverse…
Experimental simulation of Titan's atmosphere: Detection of ammonia and ethylene oxide
Coustenis, A.; Coll, P.; Raulin, F. +1 more
For several years now, an experimental simulation of Titan's atmosphere has been on going at LISA. A cold plasma is established in a gas mixture representative of the atmosphere of the satellite. In these experiments, more than 70 organic compounds have been identified, including the first identification in this type of experimental simulation of …