Search Publications
Star formation triggered by galaxy collisions
Lutz, Dieter; Genzel, Reinhard; Tacconi, Linda
It is becoming increasingly clear that collisions between galaxies play an important role in galaxy evolution. The ultraluminous infrared galaxies are predominantly powered by enormous star-formation events that are triggered in the last phases of such collisions. These bursts occur just before the galaxies merge to form single elliptical galaxies.
General relativistic satellite astrometry. I. A non-perturbative approach to data reduction
Lattanzi, M. G.; Vecchiato, A.; de Felice, F. +1 more
A general relativistic scenario is utilized to build a non-perturbative model, in Schwarzschild metric, for the representation of observed angles among star pairs. This model is then applied to an end-to-end simulation of the GAIA satellite, a concept for global astrometry within the 2000+ scientific program of the European Space Agency. GAIA is e…
Infrared standards for ISO. I. A new calibration of mid infrared photometry
Kessler, M. F.; Bouchet, P.; Metcalfe, L. +5 more
We present N, 8.7 mu m, 9.8 mu m 12.5 mu m and Q bolometry of 26 stars which were observed on the IRTF. These are primarily K giants which have been well measured at other wavelengths and are chosen to be single and non-variable. Hence the data presented provides a new homogeneous set of mid IR standards. As a test of part of the calibration strat…
Systematics of RR Lyrae Statistical Parallax. II. Proper Motions and Radial Velocities
Gould, Andrew; Popowski, Piotr
We investigate whether a misestimate of proper motions or radial velocities could have been a source of substantial systematic errors in the statistical parallax determination of the absolute magnitude of RR Lyrae stars. In an earlier paper, we showed that the statistical parallax method is extremely robust and rather insensitive to various system…
Do coronal mass ejections implode in the solar wind?
Riley, Pete; Gosling, J. T.
Ulysses observations show that many coronal mass ejections observed at high heliographic latitudes expand because they initially have higher internal pressures than that of the surrounding solar wind. This expansion commonly drives a shock wave into the ambient wind in all directions. In the analogous process of an explosion in the Earth's atmosph…
Discovery of an Optical Synchrotron Jet in 3C 15
Baum, Stefi A.; McCarthy, Patrick J.; Sparks, William B. +6 more
We report the discovery of a new optical synchrotron jet in the radio galaxy 3C 15. This brings to nine the number of known optical synchrotron jets in nearby radio galaxies. The jet is well resolved in both length and width and extends to a projected metric distance of ~5 kpc from the galaxy nucleus. The host galaxy shows complex inner structure,…
Unveiling the Hidden Nucleus of IC 5063 with NICMOS
Colina, L.; Calzetti, D.; Axon, D. +16 more
We present high-resolution near-infrared images of the Seyfert 2 galaxy IC 5063 obtained using the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) in broadband filters at 1.1, 1.6, and 2.2 µm (FWHM ~ 0.21" at 2.2 µm). The images show a very red, unresolved point source at the center of the galaxy, confirming the existence of…
Molecular Gas in the Inner 100 Parsecs of M51
Yun, M. S.; Armus, L.; Scoville, N. Z. +1 more
We report imaging of CO (2-1) emission in the nucleus of M51 at 1'' (47 pc) resolution. Molecular gas is found closely associated with the nuclear radio jet and the X-shaped dust absorption feature seen in the Hubble Space Telescope images. The CO emission lies along the side of the nuclear radio continuum ``jet.'' The strongest molecul…
ISOCAM Imaging of Comets 65P/Gunn and 46P/Wirtanen
Fulle, M.; Mennella, V.; Colangeli, L. +4 more
In this paper we present images of Comets 65P/Gunn and 46P/Wirtanen obtained by means of ISOCAM in the broadband filters at 9.62 (LW7) and 15.00 µm (LW3). The observations were performed on 23 March 1996 and on 9 November 1996, respectively. The aim of this work is to analyze the coma and tail dust environment of the targets. The application…
The Height Structure of the Solar Atmosphere from the Extreme-Ultraviolet Perspective
Kundu, M. R.; White, S. M.; Zhang, Jie
We investigate the structure of the solar chromosphere and transition region using full Sun images obtained with the Extreme-Ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory spacecraft. The limb seen in the EIT coronal images (taken in lines of Fe IX/X at 171 Å, Fe XII at 195 Å, and Fe XV at 284 Å) is an absorption…