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Photometric Calibration of the Lasco-C3 Coronagraph Using Stars
Thernisien, A. F.; Howard, R. A.; Wang, D. +1 more
The LASCO-C3 coronagraph on SOHO, launched in December 1995, has been collecting images of the corona and background star fields in a regular manner since 1996. This instrument contains a number of broadband filters with various passbands in the range between 400 and 1100 nm. The filter used most often has been the Clear filter (400-900 nm) but th…
XMM-Newton Observation of Diffuse Gas and Low-Mass X-Ray Binaries in the Elliptical Galaxy NGC 4649 (M60)
Sarazin, Craig L.; Irwin, Jimmy A.; Randall, Scott W.
We present an XMM-Newton X-ray observation of the X-ray-bright E2 elliptical galaxy NGC 4649. In addition to bright diffuse emission, we resolve 158 discrete sources, ~50 of which are likely to be LMXBs associated with NGC 4649. We find evidence for variability in three sources between this observation and a previous Chandra observation. Additiona…
Are short γ-ray bursts collimated? GRB 050709, a flare but no break
Sollerman, J.; Watson, D.; Fynbo, J. P. U. +5 more
Context: .From the small sample of afterglow lightcurves of short duration γ-ray bursts (GRBs), the decays are rapid, roughly following a power-law in time. It has been assumed that the afterglow emission in short GRBs is collimated in jets in the same way as in long GRBs.
Aims: .An achromatic break in a short GRB afterglow lightcurve would th…
Spectral Evolution of the Luminous Blue Variable NGC 2363-V1. I. Observations and Qualitative Analysis of the Ongoing Giant Eruption
Drissen, Laurent; Crowther, Paul A.; Petit, Véronique
We describe the spectroscopic evolution of the extragalactic luminous blue variable NGC 2363-V1 from 1997 to 2004. Photometrically, this star has gradually faded by 0.3 mag in the V band over this period, while spectra obtained with the Hubble Space Telescope show dramatic changes: a gradual strengthening of the UV flux (a fourfold increase at 120…
Remarkable Disk and Off-Nuclear Starburst Activity in the Tadpole Galaxy as revealed by the Spitzer Space Telescope
Berta, S.; Rodighiero, G.; Hatziminaoglou, E. +20 more
We present ground-based optical and Spitzer Space Telescope infrared imaging observations of the interacting galaxy UGC 10214, the Tadpole galaxy (z=0.0310), focusing on the star formation activity in the nuclear, disk, spiral arms, and tidal tail regions. The ground-based optical data set spans a wavelength range between 0.3 and 0.8 µm, the…
Spectral States of the X-Ray Binary IGR J17091-3624 Observed by INTEGRAL and RXTE
Capitanio, F.; Bird, A. J.; Ubertini, P. +6 more
IGR J17091-3624 was discovered in 2003 April by IBIS, the gamma-ray imager on board the INTEGRAL satellite, during its Galactic Center Deep Exposure program. The source was initially detectable only in the 40-100 keV range but after 2 days was also detected in the 15-40 keV range. Its flux had by then increased to 40 and 25 mcrab in the 15-40 and …
Ultracompact Blue Dwarf Galaxies: Hubble Space Telescope Imaging and Stellar Population Analysis
Somerville, Rachel S.; Windhorst, Rogier A.; Vacca, William D. +3 more
We present deep Hubble Space Telescope (HST) Advanced Camera for Surveys/High Resolution Channel U-, narrow-V-, and I-band images of nine ``ultracompact'' blue dwarf galaxies (UCBDs) selected from the Sloan Digital Sky Survey (SDSS). We define UCBDs as local (z<0.01) star-forming galaxies having angular diameters less than 6" and physical diame…
Stellar populations in the CFHTLS. I. New constraints on the IMF at low mass
Schultheis, M.; Bertin, E.; McCracken, H. J. +4 more
We present a stellar populations analysis of the first release of the CFHTLS (Canada-France-Hawai Telescope Legacy Survey) data. A detailed comparison between the Besançon model of the Galaxy and the first data release of the CFHTLS-Deep survey is performed by implementing the MEGACAM photometric system in this model using stellar atmosphere model…
New nearby active galactic nuclei among INTEGRAL and RXTE X-ray sources
Bikmaev, I. F.; Sunyaev, R. A.; Revnivtsev, M. G. +1 more
We present the first results of a campaign to optically identify X-ray sources discovered in the all-sky surveys of the RXTE and INTEGRAL observatories. Six newly discovered sources proved to be hitherto unknown nearby active galactic nuclei (z < 0.1). Spectrophotometric studies of these sources were performed with the Russian-Turkish 1.5-m tel…
Interaction of moist convection with zonal jets on Jupiter and Saturn
Ingersoll, Andrew P.; Li, Liming; Huang, Xianglei
Observations suggest that moist convection plays an important role in the large-scale dynamics of Jupiter's and Saturn's atmospheres. Here we use a reduced-gravity quasigeostrophic model, with a parameterization of moist convection that is based on observations, to study the interaction between moist convection and zonal jets on Jupiter and Saturn…