Search Publications
Starbursts in the Local Universe: New Hubble Space Telescope Advanced Camera for Surveys Observations of the Irregular Galaxy NGC 4449
Leitherer, C.; Tosi, M.; van der Marel, R. P. +5 more
We present photometry with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope of stars in the Magellanic starburst galaxy NGC 4449. The galaxy has been imaged in the F435W (B), F555W (V), and F814W (I) broadband filters, and in the F658N (Hα) narrowband filter. Our photometry includes ≈300,000 objects in the (B, V) color-magnitude…
NGC 3147: a `true' type 2 Seyfert galaxy without the broad-line region
Bianchi, S.; Jiménez-Bailón, E.; Barcons, X. +5 more
We report on simultaneous optical and X-ray observations of the Seyfert galaxy, NGC 3147. The XMM-Newton spectrum shows that the source is unabsorbed in the X-rays (NH < 5 × 1020 cm-2). On the other hand, no broad lines are present in the optical spectrum. The origin of this optical/X-rays misclassification (wit…
Constraining Cosmic Evolution of Type Ia Supernovae
Becker, A. C.; Sollerman, J.; Spyromilio, J. +27 more
We present a large-scale effort of creating composite spectra of high-redshift SNe Ia and comparing them to low-redshift counterparts in an attempt to understand possible cosmic evolution of SNe Ia, which has major implications for studies of dark energy. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with exc…
X-Ray Spectroscopy of SN 1006 with Suzaku
Katsuda, Satoru; Yamaguchi, Hiroya; Koyama, Katsuji +7 more
We report on observations of SN 1006 with Suzaku. We firmly detected K-shell emission from Fe, for the first time, and found that the Fe ionization state is quite low. The broad-band spectrum extracted from southeast of the remnant was well-fitted with a model consisting of three optically thin thermal non-equilibrium ionization plasmas and a powe…
Magnetosheath Plasma Turbulence and Its Spatiotemporal Evolution as Observed by the Cluster Spacecraft
André, M.; Vaivads, A.; Vörös, Z. +2 more
We study the plasma turbulence, at scales larger than the ion inertial length scale, downstream of a quasiparallel bow shock using Cluster multispacecraft measurements. We show that turbulence is intermittent and well described by the extended structure function model, which takes into account the spatial inhomogeneity of the cascade rate. For the…
Revised Orbits of Saturn's Small Inner Satellites
Porco, C. C.; Cooper, N. J.; Murray, C. D. +4 more
We have updated the orbits of the small inner Saturnian satellites using additional Cassini imaging observations through 2007 March. Statistically significant changes from previously published values appear in the eccentricities and inclinations of Pan and Daphnis, but only small changes have been found in the estimated orbits of the other satelli…
SDSSJ124155.33+114003.7 - a missing link between compact elliptical and ultracompact dwarf galaxies
Mamon, Gary A.; Chilingarian, Igor V.
We report the discovery of a compact object (Re = 32 pc, MB = -12.34 mag) at a projected distance of 9 kpc from Messier 59, a giant elliptical in the Virgo cluster. Using HST imaging and SDSS spectroscopy, both available in the Virtual Observatory, we find that this object has a blue core containing one-quarter of the light, …
Superdiffusive transport of electrons accelerated at corotating interaction regions
Zimbardo, Gaetano; Perri, Silvia
Energetic particles in the solar wind are accelerated at interplanetary shock waves associated with corotating interaction regions (CIRs) and propagate in the presence of a spectrum of magnetic turbulence, which causes pitch angle scattering upstream of the shock. Besides normal diffusive transport, we study the possibility of superdiffusive trans…
Calibrated griz Magnitudes of Tycho Stars: All-Sky Photometric Calibration Using Bright Stars
Ofek, Eran O.
Photometric calibration to ∼5% level is frequently needed at arbitrary celestial location. However, existing all-sky astronomical catalogs do not reach this accuracy, and time consuming photometric calibration procedures are required. I fitted the Hipparcos BT and VT magnitudes, along with the 2MASS J, H, and K magnitudes of …
An active region jet observed with Hinode
Young, P. R.; Mason, H. E.; Isobe, H. +4 more
Aims:We study the physical properties of an active region (AR) jet in order to probe the mechanisms responsible for it.
Methods: We report 2007 January 15/16 observations of a recurring jet situated on the west side of NOAA AR 10938. Multi-wavelength data from all three instruments onboard Hinode were analysed. This paper focuses on one instan…