Search Publications
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…
Source location of chorus emissions observed by Cluster
Maksimovic, M.; Parrot, M.; Cornilleau-Wehrlin, N. +2 more
One of the objectives of the Cluster mission is to study sources of various electromagnetic waves using the four satellites. This paper describes the methods we have applied to data recorded from the STAFF spectrum analyser. This instrument provides the cross spectral matrix of three magnetic and two electric field components. This spectral matrix…
Complex optical-X-ray correlations in the narrow-line Seyfert 1 galaxy NGC 4051
Netzer, H.; Uttley, P.; Shemmer, O. +1 more
This paper presents the results of a dense and intensive X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051 carried out in 2000. Results of the optical analysis are consistent with previous measurements. The amplitude of optical emission-line variability is a factor of 2 larger than that of the underlying optical continuum, …
Discovery of a helium-core white dwarf progenitor
Heber, U.; Napiwotzki, R.; Lisker, T. +1 more
We discovered that HD 188112, a bright (V = \magpt{10}{2}), nearby (80 pc) B-type star, is a unique subluminous B (sdB) star. SdB stars are usually identified with models of core helium burning Extreme Horizontal-Branch (EHB) stars of half a solar mass. A spectral analysis of the hydrogen and helium lines resulted in T_eff = 21 500 +/- 500 K, log …