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Venus O + pickup ions: Collected PVO results and expectations for Venus Express
Luhmann, J. G.; Russell, C. T.; Lyon, J. G. +1 more
Observations of oxygen pickup ions by the plasma analyzer on the Pioneer Venus Orbiter (PVO) Mission arguably launched broad interest in solar wind erosion of unmagnetized planet atmospheres, and its potential evolutionary effects. Oxygen pickup ions may play key roles in the removal of the oxygen excess left behind from the photodissociation of w…
The Structure and Star Formation History of Early-Type Galaxies in the Ultra Deep Field/GRAPES Survey
Daddi, E.; Panagia, N.; Koekemoer, A. M. +9 more
We present a two-pronged approach to the formation of early-type galaxies, using a sample of 18 galaxies at 0.5<~z<~1 from the HST ACS Ultra Deep Field and GRAPES surveys: (1) We combine slitless low-resolution spectroscopy from the GRAPES data set with simple models of galaxy formation to explore their star formation histories. (2) We also …
The Pulsar Wind Nebula of the Geminga Pulsar
Pavlov, G. G.; Zavlin, V. E.; Sanwal, D.
The superb spatial resolution of Chandra has allowed us to detect a 20" long tail behind the Geminga pulsar, with a hard spectrum (photon index Γ=1.0+/-0.2) and a luminosity of (1.3+/-0.2)×1029 ergs s-1 in the 0.5-8 keV band, for an assumed distance of 200 pc. The tail could be either a pulsar jet, confined by a toroidal magn…
Spectroscopic Redshifts for Seven Lens Galaxies
Maoz, Dan; Rix, Hans-Walter; Kochanek, Christopher S. +2 more
The use of gravitationally lensed quasars for cosmological applications and as probes of galaxy structure and evolution requires knowledge about the lens redshift, which is unknown for a large fraction of lenses. We report Very Large Telescope observations of 11 lensed quasars, designed to measure the redshifts of their lens galaxies. We successfu…
Kinematics of Interstellar Gas in Nearby UV-selected Galaxies Measured with HST STIS Spectroscopy
Leitherer, C.; Oey, M. S.; Heckman, T. M. +3 more
We measure Doppler shifts of interstellar absorption lines in HST STIS spectra of individual star clusters in nearby UV-selected galaxies. Values for systemic velocities, which are needed to quantify outflow speeds, are taken from the literature and verified with stellar lines. We detect outflowing gas in 8 of 17 galaxies via low-ionization lines …
Precision Kinematics and Related Parameters of the α Persei Open Cluster
Makarov, Valeri V.
A kinematical study of the nearby open cluster α Persei is presented based on the astrometric proper motions and positions in the Tycho-2 catalog and Second USNO CCD Astrographic Catalog (UCAC2). Using the astrometric data and photometry from the Tycho-2 and ground-based catalogs, 139 probable members of the cluster are selected, 18 of them new. B…
Warm Water Vapor around Sagittarius B2
Cernicharo, José; Goicoechea, Javier R.; Pardo, Juan R. +1 more
Several condensations heated externally by nearby hot stars are present in the Sgr B2 region for which H2O far-IR lines are expected to probe only an external low-density and high temperature section. Millimeter-wave lines can penetrate deeper into them (higher densities and lower Tk). We have conducted a study combining H
XMM-Newton observations of bright ROSAT selected active galactic nuclei with low intrinsic absorption
Pietsch, W.; Boller, Th.; Brinkmann, W. +4 more
We present a sample of 21 ROSAT bright active galactic nuclei (AGNs), representing a range of spectral classes, and selected for follow-up snapshot observations with XMM-Newton. The typical exposure was between 5 and 10ks. The objects were primarily selected on the bases of X-ray brightness and not on hardness ratio; thus the sample cannot be stri…
New γ Cassiopeiae-like objects: X-ray and optical observations of SAO 49725 and HD 161103
Haberl, F.; Motch, C.; Janot-Pacheco, E. +2 more
A growing number of early Be stars exhibit X-ray luminosities that are intermediate between those typical of early type stars and those emitted by most Be/X-ray binaries in quiescence. We report on XMM-Newton observations of two such Be stars,
Milliarcsecond-Scale Spectral Properties and Jet Motions in M 87
Dodson, Richard; Edwards, Philip G.; Hirabayashi, Hisashi
We have combined high resolution VLBI Space Observatory Programme (VSOP) data at 1.6 and 4.8GHz with Very Long Baseline Array (VLBA) data at higher frequencies and with similar resolutions to study the spectral properties of the core of M 87 with milliarcsec resolution. The VSOP data allows a more accurate measurement of the turnover frequency, an…