Search Publications
Star Formation Histories from Hubble Space Telescope Color-Magnitude Diagrams of Six Fields of the Large Magellanic Cloud
Olsen, Knut A. G.
We present results on the analysis of background field stars found in Hubble Space Telescope Wide Field Planetary Camera 2 observations of six of the old globular clusters of the Large Magellanic Cloud. Treated as contaminants by the globular cluster analysts, we produce (V-I,V) color-magnitude diagrams (CMDs) of the field stars and use them to ex…
Seyfert 1 Mutation of the Classical Seyfert 2 Nucleus NGC 7582
Kunth, D.; Aretxaga, Itziar; Terlevich, R. J. +2 more
We report the transition toward a type 1 Seyfert experienced by the classical type 2 Seyfert nucleus in NGC 7582. The transition, found at most 20 days from its maximum peak, presents a unique opportunity to study these rare events in detail. At maximum, the Hα line width is about 12,000 km s-1. We examine three scenarios that could pot…
Water Ice, Silicate, and Polycyclic Aromatic Hydrocarbon Emission Featuresin the Infrared Space Observatory Spectrum of the Carbon-richPlanetary Nebula CPD -56°8032
Barlow, M. J.; Liu, X. -W.; Cox, P. +5 more
Combined Infrared Space Observatory Short-Wavelength Spectrometer and Long-Wavelength Spectrometer spectroscopy is presented of the late WC-type planetary nebula nucleus CPD -56°8032 and its carbon-rich nebula. The extremely broad coverage (2.4-197 µm) enables us to recognize the clear and simultaneous presence of emission features from both…
Structure and colour-magnitude diagrams of Scorpius OB2 based on kinematic modelling of Hipparcos data
de Bruijne, Jos H. J.
All stars in a `moving group' share the same space motion. The presence of such a coherent structure in velocity space can be used to derive (improved) estimates of the stellar parallaxes from the observed positions and proper motions. A Lund Observatory group (Dravins et al.) describes an elegant and sophisticated maximum likelihood procedure to …
The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XV. A Cepheid Distance to the Fornax Cluster and Its Implications
Illingworth, Garth D.; Madore, Barry F.; Freedman, Wendy L. +13 more
Using the Hubble Space Telescope, 37 long-period Cepheid variables have been discovered in the Fornax Cluster spiral galaxy NGC 1365. The resulting V and I period-luminosity relations yield a true distance modulus of µ0=31.35+/-0.07 mag, which corresponds to a distance of 18.6+/-0.6 Mpc. This measurement provides several routes fo…
Looking at the bright side of the rho Ophiuchi dark cloud. Far infrared spectrophotometric observations of the rho Oph cloud with the ISO
Olofsson, G.; Liseau, R.; White, G. J. +9 more
We present far infrared (45-195 mu m) spectrophotometric observations with the Iso-Lws of the active star forming rho Oph main cloud (L 1688). The [C ii] 158 mu m and [O i] 63 mu m lines were detected at each of the 33 positions observed, whereas the [O i] 145 mu m line was clearly seen toward twelve. The principal observational result is that the…
Some Characteristics of Current Star Formation in the 30 Doradus Nebula Revealed by HST/NICMOS
Walborn, Nolan R.; Grebel, Eva K.; Brandner, Wolfgang +3 more
The extensive ``second generation'' of star formation within the 30 Doradus Nebula, evidently triggered by the R136 central cluster around its periphery, has been imaged with the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope. Many new IR sources, including multiple systems, clusters, and nebular structur…
Far-Ultraviolet Imaging Spectroscopy of Io's Atmosphere with HST/STIS
Feldman, P. D.; Moos, H. W.; Strobel, D. F. +7 more
A deep VLA survey at 20 CM of the ISO ELAIS survey regions
Genzel, R.; Cesarsky, C.; Danese, L. +11 more
We have used the Very Large Array (VLA) in C configuration to carry out a sensitive 20-cm radio survey of regions of sky that have been surveyed in the far-infrared (FIR) over the wavelength range 5--200 µm with ISO (Infrared Space Observatory) as part of the European Large-Area ISO Survey (ELAIS). As usual in surveys based on a relatively s…
Seismic Images of a Solar Flare
Braun, D. C.; Lindsey, C.; Donea, A. -C.
We have used helioseismic holography to render seismic images of the solar flare of 1996 July 9, whose helioseismic signature was recently reported by Kosovichev & Zharkova. We computed time series of ``egression power maps'' in 2 mHz bands centered at 3.5 and 6 mHz. These images suggest an oblong acoustic source associated with the flare some…