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Comets in full sky Lalpha maps of the SWAN instrument. I. Survey from 1996 to 1998
Schmidt, W.; Bertaux, J. -L.; Lallement, R. +5 more
The SWAN instrument onboard the SOHO spacecraft is a Lyman alpha scanning photometer cabable of mapping the whole sky with 1degr resolution. Since January 1996 the instrument has produced on average three full sky maps a week with the principal scientific objective of observing the distribution of heliospheric neutral hydrogen. In addition, these …
Stellar Encounters with the β Pictoris Planetesimal System
Kalas, Paul; Deltorn, Jean-Marc; Larwood, John
We use data from the Hipparcos catalog and the Barbier-Brossat & Figon catalog of stellar radial velocities to test the hypothesis that the β Pic planetesimal disk was disrupted by a close stellar encounter. We trace the space motions of 21,497 stars and discover 18 that have passed within 5 pc of β Pic in the past 1 Myr. β Pic's closest encou…
Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder
Fergeau, P.; Décréau, P. M. E.; Canu, P. +9 more
We use the data collected by the Whisper instrument onboard the Cluster spacecraft for a first test of its capabilities in the identification of the natural plasma waves observed in the Earth's magnetosphere. The main signatures observed at the plasma frequency, upper hybrid frequency, and electron Bernstein modes were often difficult to be reliab…
Detection of a Corrugated Velocity Pattern in the Spiral Galaxy NGC 5427
Pérez, Enrique; Alfaro, Emilio J.; González Delgado, Rosa M. +2 more
Here we report the detection, in Hα emission, of a radial corrugation in the velocity field of the spiral galaxy NGC 5427. The central velocity of the Hα line displays coherent, wavy-like variations in the vicinity of the spiral arms. The spectra along three different arm segments show that the maximum amplitude of the sinusoidal line variations a…
HST study of the LMC compact star-forming region N83B
Schaerer, D.; Heydari-Malayeri, M.; Charmandaris, V. +3 more
High resolution imaging with the Hubble Space Telescope has uncovered the thus far hidden stellar content and the nebular features of the high excitation compact H ii region N83B in the Large Magellanic Cloud (LMC). We discover that the H ii region is powered by the most recent massive starburst in the OB association LH 5 and the burst has created…
Inhomogeneous metal enrichment at z ~ 1.9: The Lyman limit systems in the spectrum of the HDF-S quasar
D'Odorico, V.; Petitjean, P.
We present a detailed analysis of three metal absorption systems observed in the spectrum of the HDF-South quasar J2233-606 (z_em=2.238), taking advantage of new VLT-UVES high resolution data (R=45 000, S/N=40-60, lambda lambda 3050-10 000 Å). Three main components, spanning about 300 km s-1, can be distinguished in the Lyman limit syst…
The Super-Star Cluster NGC 1569-A Resolved on Subparsec Scales with Hubble Space Telescope Spectroscopy
Ho, Luis C.; Maoz, Dan; Sternberg, Amiel
We present 3000-10000 Å Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph long-slit spectroscopy of the bright super-star cluster A (SSC-A) in the dwarf starburst galaxy NGC 1569. The 0.05" HST angular resolution allows us, for the first time, to probe for spatial variations in the stellar population of an ~106 Msol…
Modelling the first probable two-plane lens system B2114+022: reproducing two compact radio cores A and D
Mao, Shude; Chae, Kyu-Hyun; Augusto, Pedro
We test possible lensing scenarios of the JVAS system B2114+022, in which two galaxies at different redshifts (`G1' at z1=0.3157 and `G2' at z2=0.5883) are found within 2arcsec of quadruple radio sources. For our investigation, we use possible lensing constraints derived from a wealth of data on the radio sources obtained wit…
Radial Color Gradients in K+A Galaxies in Distant Clusters of Galaxies
Caldwell, Nelson; Rose, James A.; Bartholomew, Lindsay J. +1 more
Galaxies in rich clusters with z>~0.3 are observed to have a higher fraction of photometrically blue galaxies than their nearby counterparts. This raises the important question of what environmental effects can cause the termination of star formation between z~0.3 and the present. The star formation may be truncated because of ram pressure stri…
21-cm H I emission from the Damped Lyman-alpha absorber SBS 1543+593
Jenkins, E. B.; Brinks, E.; Bowen, D. V. +2 more
We detect 21-cm emission from the Low Surface Brightness (LSB) galaxy SBS 1543+593, which gives rise to a Damped-Lyalpha (DLyalpha ) absorption line in the spectrum of the background QSO HS 1543+5921 (ze = 0.807). We obtain an accurate measure of the velocity of the H I gas in the LSB galaxy, v = 2868 km s-1, and derive a mas…