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From Globular Clusters to Tidal Dwarfs: Structure Formation in the Tidal Tails of Merging Galaxies
Charlton, Jane C.; Kundu, Arunav; Gallagher, Sarah C. +5 more
Using V and I images obtained with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope, we investigate compact stellar structures within tidal tails. Six regions of tidal debris in the four classic ``Toomre sequence'' mergers: NGC 4038/39 (``Antennae''), NGC 3256, NGC 3921, and NGC 7252 (``Atoms for Peace'') have been studied i…
F stars, metallicity and the ages of red galaxies at z > 1
Dunlop, J. S.; Nolan, L. A.; Jimenez, R. +1 more
We explore whether the rest-frame near-ultraviolet spectral region, observable in high-redshift galaxies via optical spectroscopy, contains sufficient information to allow the degeneracy between age and metallicity to be lifted. We do this by first testing the ability of evolutionary synthesis models to reclaim the correct metallicity when fitted …
The conspicuous absence of X-ray emission from carbon-enriched Wolf-Rayet stars
Hamann, W. -R.; Oskinova, L. M.; Ignace, R. +2 more
The carbon-rich WC5 star WR 114 was not detected during a 15.9 ksec XMM-Newton, observation, implying an upper limit to the X-ray luminosity of LX <∼ 2.5x 1030 erg s-1 and to the X-ray to bolometric luminosity ratio of LX/Lbol <∼ 4*E-9. This confirms indications from earlier l…
WIYN Open Cluster Study. XVII. Astrometry and Membership to V=21 in NGC 188
Kozhurina-Platais, Vera; Girard, Terrence M.; van Altena, William F. +2 more
We present techniques for obtaining precision astrometry using old photographic plates from assorted large-aperture reflectors in combination with recent CCD Mosaic Imager frames. At the core of this approach is a transformation of plate/CCD coordinates into a previously constructed astrometric reference frame around the open cluster NGC 188. This…
Large Disklike Galaxies at High Redshift
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +11 more
Using deep near-infrared imaging of the Hubble Deep Field-South with the Infrared Spectrometer and Array Camera on the Very Large Telescope, we find six large disklike galaxies at redshifts z=1.4-3.0. The galaxies, selected in Ks (2.2 µm), are regular and surprisingly large in the near-infrared (rest-frame optical), with face-on e…
The Effect of Proton Temperature Anisotropy on the Solar Minimum Corona and Wind
Raymond, John C.; Vásquez, Alberto M.; van Ballegooijen, Adriaan A.
A semiempirical, axisymmetric model of the solar minimum corona is developed by solving the equations for conservation of mass and momentum with prescribed anisotropic temperature distributions. In the high-latitude regions, the proton temperature anisotropy is strong and the associated mirror force plays an important role in driving the fast sola…
XMM-Newton observations of the hot-gas atmospheres of 3C 66B and 3C 449
Hardcastle, M. J.; Croston, J. H.; Birkinshaw, M. +1 more
We present new XMM-Newton observations of the hot-gas environments of two low-power twin-jet radio galaxies, 3C 66B and 3C 449, showing direct evidence for the interactions between X-ray-emitting gas and radio plasma that are thought to determine the large-scale radio structure of these sources. The temperatures that we measure for the two environ…
Mission: impossible (escape from the Lyman limit)
Fernández-Soto, A.; Chen, H. -W.; Lanzetta, K. M.
We investigate the intrinsic opacity of high-redshift galaxies to outgoing ionizing photons using high-quality photometry of a sample of 27 spectroscopically identified galaxies of redshift 1.9 < z < 3.5 in the Hubble Deep Field. Our measurement is based on maximum-likelihood fitting of model galaxy spectral energy distributions - including …
An XMM-Newton observation of the globular cluster Omega Centauri
Webb, N. A.; Barret, D.; Gendre, B.
We report on a deep XMM-Newton EPIC observation of the globular cluster Omega Cen performed on August 13th, 2001. We have detected 11 and 27 faint X-ray sources in the core and half mass radii, searching down to a luminosity of 1.3 x 1031 ergs s-1 in the 0.5-5 keV range. Most sources have bolometric X-ray luminosities between…
XMM-Newton spectral properties of the narrow-line Seyfert 1 galaxy IRAS 13224 - 3809
Brandt, W. N.; Vaughan, S.; Boller, Th. +5 more
We report on the first XMM-Newton observation of the highly X-ray variable, radio-quiet, narrow-line Seyfert 1 galaxy IRAS 13224 - 3809 obtained during the guaranteed time programme with a 64-ks exposure. The most remarkable spectral feature is a sharp drop, by a factor of ~5, in the spectrum at 8 keV. This is a similar, but stronger, feature to t…