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The Ofpe/WN9 Stars in M33
Massey, Philip; Bianchi, Luciana; Bohlin, Ralph
We present Hubble Space Telescope/STIS Ultraviolet spectra of the six known Ofpe/WN9 stars (``slash stars'') in M33. These stars were selected for showing the characteristics of the Ofpe/WN9 class from previous optical ground-based spectroscopy. The UV spectra are rich in wind lines whose strength and terminal velocity vary greatly across our targ…
The nearest extreme starburst: bubbles, young star clusters and outflow in the merger NGC 3256
Taniguchi, Y.; Terlevich, R.; Díaz, R. J. +6 more
We have studied the extreme starburst in the infrared merger NGC 3256. We detect four galactic bubbles (using ESO New Technology Telescope and Hubble Space Telescope WFPC2 Hα images). These shells would be associated with previous supernova explosions.
The first analysis of the spatial distribution of young star cluster candidates shows that …NGC 6543. II. Understanding the Dilation of the Cat's Eye
Balick, Bruce; Hajian, Arsen R.
Hubble Space Telescope images of NGC 6543 taken in 1994.7 and 2000.7 reveal a pattern of overall expansion of its core over 6 years. Spatial scale changes of the sharp edges of filamentary structures are consistent with purely radial motions. One prolate ellipsoid, E25, lies along the overall symmetry axis of the core. We find that it expands unif…
Dynamics of the fast solar tachocline. II. Migrating field
Forgács-Dajka, E.
We present detailed numerical calculations of the fast solar tachocline based on the assumption that the dynamo field dominates over the dynamics of the tachocline. In the present paper of the series, we focus on three shortfalls of the earlier models. First, instead of the simple oscillating dipole poloidal field we study the more general magneti…
The field surrounding NGC 7603: Cosmological or non-cosmological redshifts?
López-Corredoira, M.; Gutiérrez, C. M.
We present new observations of the field surrounding the Seyfert galaxy NGC 7603, where four galaxies with different redshifts - NGC 7603 (z=0.029), NGC 7603B (z=0.057) and two fainter emission line galaxies (z=0.245 and z=0.394) - are apparently connected by a narrow filament, leading to a possible case of anomalous redshift. The observations com…
Keck Spectroscopy of Two Young Globular Clusters in the Merger Remnant NGC 3921
Brodie, Jean P.; Seitzer, Patrick; Schweizer, François
Low-resolution, ultraviolet-to-visual spectra of two candidate globular clusters in the merger remnant NGC 3921 (czLG=6021 km s-1) are presented. These two clusters of apparent magnitude V~22.2 (MV~-12.5) lie at projected distances of about 5 kpc (0.9 Reff) from the center and move with halo-type radial …
The complex structure of low-luminosity active galactic nuclei: NGC 4579
Contini, Marcella
We have modelled the low-luminosity active galactic nucleus (AGN) NGC 4579 by explaining both the continuum and the line spectra observed with different apertures. It was found that the nuclear emission is dominated by an AGN such that the flux from the active centre (AC) is relatively low compared with that of the narrow emission-line region (NLR…
Astrophysical supplements to the ASCC-2.5. I. Radial velocity data
Scholz, R. -D.; Piskunov, A. E.; Kharchenko, N. V.
We present a catalogue of radial velocities of Galactic stars with high precision astrometric data CRVAD which is the result of the cross-identification of star lists from the General Catalog of Average Radial Velocities (GCRV) and from the homogeneous All-sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5). The CRVAD includes accurate J2000 eq…
Detection of Nitrogen and Neon in the X-Ray Spectrum of GP Comae Berenices with XMM/Newton
Strohmayer, Tod E.
We report on X-ray spectroscopic observations with XMM/Newton of the ultracompact, double white dwarf binary GP Com. With the Reflection Grating Spectrometers (RGSs), we detect the Lyα and Lyβ lines of hydrogen-like nitrogen (N VII) and neon (Ne X), as well as the helium-like triplets (N VI and Ne IX) of these same elements. All the emission lines…
Study of the vertical structure of Saturn's atmosphere using HST/WFPC2 images
Moreno, F.; Grodent, D.; Dols, V. +3 more
We have studied the vertical structure of hazes at six different latitudes (-60°, -50°, -30°, -10°, +30°, and +50°) on Saturn's atmosphere. For that purpose we have compared the results of our forward radiative transfer model to limb-to-limb reflectivity scans at four different wavelengths (230, 275, 673.2, and 893 nm). The images were obtained wi…