Search Publications
Weak gravitational lensing around field galaxies in Hubble Space Telescope survey images
Im, M.; Griffiths, R. E.; Casertano, S. +1 more
Using data from the Hubble Space Telescope (HST) Medium Deep Survey, a long-term key project, together with generically similar archived data, we have discovered evidence for weak gravitational `shear' of background field galaxies (I=22-26) in the vicinity of isolated, foreground galaxies (I=15-22), especially those of early type. The statistical …
Hubble Space Telescope Observations of the Unusual Blue Compact Dwarf Galaxy Markarian 996
Thuan, Trinh X.; Izotov, Yuri I.; Lipovetsky, Valentin A.
We present Hubble Space Telescope Wide Field Planetary Camera 2 V and I images and Faint Object Spectrograph UV and optical spectrophotometry of the unusual blue compact dwarf galaxy Mrk 996. We found Mrk 996 to have a disk structure with a small scale length (0.4 kpc) and a two-arm spiral-like pattern confined to the inner 160 pc in radius. Nearl…
Unlensing Multiple Arcs in 0024+1654: Reconstruction of the Source Image
Tyson, J. Anthony; Turner, Edwin L.; Colley, Wesley N.
A unique reconstruction of the image of a high-redshift source galaxy responsible for multiple long arcs in the z = 0.4 cluster 0024+1654 is obtained by inverse lensing. Deep B- and I-band imaging with the Hubble Space Telescope enables high resolution of the arcs due to strong gravitational lensing of the background source. The gravitational lens…
A laboratory database of solid CO and CO_2_ for ISO.
van Dishoeck, E. F.; Schutte, W. A.; Tielens, A. G. G. M. +4 more
We present laboratory measured infrared spectra of mixtures containing CO and CO_2_ at low temperatures. The profiles and peak position of the absorption features due to these species are very sensitive to molecular environment, temperature, irradiation history and particle shape. Illustrative examples of these variations are briefly discussed. We…
The rate of turbulent evolution over the Sun's poles.
Balogh, A.; Horbury, T. S.; Forsyth, R. J. +1 more
Ulysses magnetic field observations in the polar heliosphere have revealed the presence of a population of turbulent fluctuations on small scales with a power spectral index near 5/3 and its extension to progressively larger scales with solar distance. Using the spectral index - calculated from the second order structure function - as a tracer of …
Hubble Space Telescope Observations of Isolated Pulsars
Cordova, F. A.; Pavlov, G. G.; Stringfellow, G. S.
Using the COSTAR corrected Faint Object Camera on the Hubble Space Telescope, we have obtained deep ultraviolet and optical images of the fields containing three nearby radio pulsars spanning a range in age between ∼1 × 105 and 2 × 107 yr. Deep 7".4 × 7".4 images were obtained in the long-pass F130LP filter for the youngest, …
Identification of a gravitationally lensed z=2.515 star-forming galaxy
Smail, I.; Kneib, J. -P.; Sanahuja, B. +4 more
We discuss the optical spectrum of a multiply imaged arc resolved by the Hubble Space Telescope in the z=0.175 cluster A2218. The spectrum, obtained with LDSS-2 on the 4.2-m William Herschel Telescope, reveals the source to be a galaxy at a redshift z=2.515, in excellent agreement with the value predicted by Kneib et al. on the basis of their inve…
The ISO/LWS far infrared spectrum of IRC+10 216.
Walker, H. J.; Omont, A.; Ade, P. A. R. +41 more
We present an ISO Long Wavelength Spectrometer (LWS) grating spectrum of the carbon-rich circumstellar envelope -CSE- of IRC+10216 between 43 and 197µm. The spectrum consists of strong dust emission plus a forest of emission lines from CO, HCN, H^13^CN and vibrationally excited HCN (ν_2_=1^1^,2^0,2^ and ν_1,3_=1). All the CO lines between J=…
A month in the life of NGC 4151: velocity-delay maps of the broad-line region
Horne, Keith; Ulrich, Marie-Helene
We analyse continuum and emission-line variability in NGC 4151 based on IUE spectra taken with nearly complete 1-d sampling over a 35-d interval during 1991 November-December. The 1320-Angstroms continuum undertook a bumpy exponential decline by a factor ~3 over 25 d, and then made a dramatic recovery in ~2d near the end of the campaign. The same …
Main-Sequence Stars and the Star Formation History of the Outer Disk in the Large Magellanic Cloud
Krist, J.; Gallagher, J. S.; Stappers, B. +17 more
Using the Wide Field Planetary Camera 2 on the Hubble Space Telescope, we have obtained a deep color-magnitude diagram in V- and I-band equivalents for more than 2000 stars in a patch of the outer disk of the Large Magellanic Cloud (LMC). Aperture photometry is feasible from these data with good signal-to-noise ratio for stars with V <= 25, whi…