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Imaging the circumstellar envelopes of AGB stars
Mauron, N.; Huggins, P. J.
Aims.We report the results of an exploratory program to image the extended circumstellar envelopes of asymptotic giant branch (AGB) stars in dust-scattered galactic light. The goal is to characterize the morphology of the envelopes as a probe of the mass-loss process.
Methods: .The observations consist of short exposures with the VLT and longe…
Evolution of Coronal Mass Ejections in the Inner Heliosphere: A Study Using White-Light and Scintillation Images
Manoharan, P. K.
Knowledge of the radial evolution of the coronal mass ejection (CME) is important for the understanding of its arrival at the near-Earth space and of its interaction with the disturbed/ambient solar wind in the course of its travel to 1 AU and further. In this paper, the radial evolution of 30 large CMEs (angular width > 150∘, i.e., …
Radio, X-ray, and γ-ray emission models of the colliding-wind binary WR140
Pittard, J. M.; Dougherty, S. M.
We use hydrodynamical models of the wind-collision region in the archetype colliding-wind system WR140 to determine the spatial and spectral distributions of the radio, X-ray, and γ-ray emission from shock-accelerated electrons. Our calculations are for orbital phase 0.837 when the observed radio emission is close to maximum. Using the observed th…
Models for the Type Ic Hypernova SN 2003lw associated with GRB 031203
Della Valle, Massimo; Tominaga, Nozomu; Nomoto, Ken'ichi +10 more
The gamma-ray burst GRB 031203 at a redshift z=0.1055 revealed a highly reddened Type Ic supernova, SN 2003lw, in its afterglow light. This is the third well-established case of a link between a long-duration GRB and a Type Ic SN. The SN light curve is obtained by subtracting the galaxy contribution and is modeled together with two spectra at near…
A Multiwavelength Study of Sgr A*: The Role of Near-IR Flares in Production of X-Ray, Soft γ-Ray, and Submillimeter Emission
Dowell, C. D.; Bélanger, G.; Goldwurm, A. +8 more
Although Sgr A* is known to be variable in radio, millimeter, near-IR, and X-rays, the correlation of the variability across its spectrum has not been fully studied. Here we describe highlights of the results of two observing campaigns in 2004 to investigate the correlation of flare activity in different wavelength regimes, using a total of nine g…
Ca II Triplet Spectroscopy of Large Magellanic Cloud Red Giants. I. Abundances and Velocities for a Sample of Populous Clusters
Smith, Verne V.; Cole, Andrew A.; Sarajedini, Ata +2 more
Using the FORS2 instrument on the Very Large Telescope, we have obtained near-infrared spectra for more than 200 stars in 28 populous LMC clusters. This cluster sample spans a large range of ages (~1-13 Gyr) and metallicities (-0.3>~[Fe/H]>~-2.0) and has good areal coverage of the LMC disk. The strong absorption lines of the Ca II triplet ar…
Spectral changes during dipping in low-mass X-ray binaries due to highly-ionized absorbers
Kaastra, J. S.; Díaz Trigo, M.; Parmar, A. N. +2 more
X-ray observations have revealed that many microquasars and low-mass X-ray binaries (LMXBs) exhibit narrow absorption features identified with resonant absorption from Fe XXV and Fe XXVI and other abundant ions. In many well studied systems there is evidence for blue-shifts, indicating outflowing plasmas. We succesfully model the changes in both t…
Probing the Coevolution of Supermassive Black Holes and Quasar Host Galaxies
Ho, Luis C.; Rix, Hans-Walter; Peng, Chien Y. +2 more
At low redshift, there are fundamental correlations between the mass of supermassive black holes (MBH) and the mass (Mbulge) and luminosity of the host galaxy bulge. We investigate the same relation at z>~1. Using virial mass estimates for 11 quasars at z>~2 to measure their black hole mass, we find that black holes at …
The multi-phase gaseous halos of star forming late-type galaxies. I. XMM-Newton observations of the hot ionized medium
Pietsch, W.; Dettmar, R. -J.; Rossa, J. +2 more
This study presents first results from an X-ray mini-survey carried out with XMM-Newton to investigate the diffuse Hot Ionized Medium in the halos of nine nearby star-forming edge-on spiral galaxies. Diffuse gaseous X-ray halos are detected in eight of our targets, covering a wide range of star formation rates from quiescent to starburst cases. Fo…
Nonthermal High-Energy Emission from Colliding Winds of Massive Stars
Reimer, A.; Reimer, O.; Pohl, M.
Colliding winds of massive star binary systems are considered as potential sites of nonthermal high-energy photon production. Motivated by the detection of synchrotron radio emission from the colliding wind location, we here investigate the properties of high-energy photon production in colliding winds of long-period WR+OB systems. Analytical form…