Search Publications
First identification and modelling of SPI background lines
Knödlseder, J.; Schönfelder, V.; Diehl, R. +17 more
On Oct. 17, 2002, the ESA INTEGRAL observatory was launched into a highly elliptical orbit. SPI, a high resolution Ge spectrometer covering an energy range of 20-8000 keV, is one of its two main instruments. We use data recorded early in the mission (i.e. in March 2003) to characterize the instrumental background, in particular the many gamma-ray …
Space Telescope Imaging Spectrograph Slitless Observations of Small Magellanic Cloud Planetary Nebulae: A Study on Morphology, Emission-Line Intensity, and Evolution
Mutchler, Max; Villaver, Eva; Blades, J. Chris +3 more
A sample of 27 planetary nebulae (PNs) in the Small Magellanic Cloud (SMC) have been observed with the Hubble Space Telescope Imaging Spectrograph (HST/STIS) to determine their morphology, size, and the spatial variation of the ratios of bright emission lines. The morphologies of SMC PNs are similar to those of LMC and Galactic PNs. However, only …
NICMOS Coronagraphic Observations of the GM Aurigae Circumstellar Disk
Schneider, G.; Wood, K.; Silverstone, M. D. +5 more
We present Hubble Space Telescope Near Infrared Camera and Multi-Object Spectrometer (NICMOS) coronagraphic observations of the environment in the region of the young star-disk system GM Aurigae. Scattered near-infrared light in two spectral bands (F110W=1.1 µm and F160W=1.6 µm) trace the morphology of circumstellar dust to a distance …
Discovery of Two Distant Type Ia Supernovae in the Hubble Deep Field-North with the Advanced Camera for Surveys
White, Richard L.; Broadhurst, Tom; Franx, Marijn +30 more
We present observations of the first two supernovae discovered with the recently installed Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). The supernovae were found in Wide Field Camera images of the Hubble Deep Field-North taken with the F775W, F850LP, and G800L optical elements as part of the ACS guaranteed time observatio…
Properties of high heliolatitude solar energetic particle events and constraints on models of acceleration and propagation
Balogh, A.; Krucker, S.; Dalla, S. +10 more
We analyse 9 large solar energetic particle (SEP) events detected by the Ulysses spacecraft at high heliolatitudes during the recent solar maximum polar passes. Properties of time intensity profiles from the Ulysses/COSPIN instrument are compared with those measured by SOHO/COSTEP and Wind/3DP near Earth. We find that onset times and times to maxi…
The Phase Coherence of Light from Extragalactic Sources: Direct Evidence against First-Order Planck-Scale Fluctuations in Time and Space
Lieu, Richard; Hillman, Lloyd W.
We present a method of directly testing whether time continues to have its usual meaning on scales of <=tP=(ℏG/c5)1/2~5.4×10-44 s, the Planck time. According to quantum gravity, the time t of an event cannot be determined more accurately than a standard deviation of the form σt/t=a0
ISOCAM view of the starburst galaxies M 82 , NGC 253 and NGC 1808
Förster Schreiber, N. M.; Sauvage, M.; Vigroux, L. +4 more
We present results of mid-infrared lambda = 5.0-16.5 µm spectrophotometric imaging of the starburst galaxies
Further Evidence for Chemical Fractionation from Ultraviolet Observations of Carbon Monoxide
Andersson, B. -G.; van Dishoeck, Ewine F.; Federman, S. R. +4 more
Ultraviolet absorption from interstellar 12CO and 13CO was detected toward ρ Oph A and χ Oph. The measurements were obtained at medium resolution with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. Column density ratios, N(12CO)/N(13CO), of 125+/-23 and 117+/-35 were derived for …
Follow-Up Hubble Space Telescope/Space Telescope Imaging Spectroscopy of Three Candidate Tidal Disruption Events
Komossa, S.; Grupe, D.; Halpern, J. P. +2 more
Large-amplitude, high-luminosity, soft X-ray flares were detected by the ROSAT All-Sky Survey in several galaxies with no evidence for Seyfert activity in their ground-based optical spectra. These flares had the properties predicted for a tidal disruption event by a central supermassive black hole: soft X-ray spectrum, timescale of months, and lar…
Star cluster formation and disruption time-scales - II. Evolution of the star cluster system in the fossil starburst of M82
de Grijs, Richard; Bastian, Nate; Lamers, Henny J. G. L. M.
We obtain new age and mass estimates for the star clusters in the fossil starburst region B of M82, based on improved fitting methods. Our new age estimates confirm the peak in the age histogram attributed to the last tidal encounter with M81; we find a peak formation epoch at slightly older ages than previously published, log(tpeak yr<…