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Luminosity Evolution of Early-Type Galaxies to z = 0.83: Constraints on Formation Epoch and Ω
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +1 more
We present deep Keck telescope spectroscopy of eight galaxies in the luminous X-ray cluster MS 1054-03 at z=0.83. The data are combined with imaging observations from the Hubble Space Telescope (HST). The spectroscopic data are used to measure the internal kinematics of the galaxies, and the HST data are used to measure their structural parameters…
The Angular Clustering of Lyman-Break Galaxies at Redshift Z approximately 3
Giavalisco, Mauro; Dickinson, Mark E.; Pettini, Max +3 more
We have measured the angular correlation function w(θ) for a sample of 871 Lyman-break galaxies (LBGs) in five fields at redshift z ~ 3. Fitting the power law Aw θ-β to a weighted average of w(θ) from the five fields over the range 12" <~ θ <~ 330", we find Aw ~ 2 arcsecβ and β ~ 0.9. The slope is,…
Spiral Galaxies with WFPC2. II. The Nuclear Properties of 40 Objects
Carollo, C. M.; Stiavelli, M.; Mack, J.
We report the analysis of Hubble Space Telescope Wide Field Planetary Camera 2 F606W images of 40 spiral galaxies belonging to the sample introduced in Paper I, where 35 other targets were discussed. We describe the optical morphological properties of the new 40 galaxies, derive the surface brightness profiles for 25 of them, and present the resul…
An ultraviolet, optical and infrared study of Herbig Ae/Be stars
Waelkens, C.; Malfait, K.; Bogaert, E.
We have selected a list of 45 Herbig Ae/Be-type candidates on the base of their IRAS colors and their spectral types. We propose the presence of a broad infrared excess as a defining criterion for these stars, rather than the detection of circumstellar nebulosity. In this way, our selection also includes more evolved young stars, that are no longe…
Interstellar reddening from the HIPPARCOS and TYCHO catalogues. I. Distances to nearby molecular clouds and star forming regions
Knude, J.; Hog, E.
The Hipparcos and Tycho Catalogues offer an interesting possibility to study the local distribution of interstellar reddening from the combination of data contained in the catalogues: Hipparcos parallaxes, Tycho B - V and spectral and luminosity classification compiled from the literature. Parallactic distances may be derived for known absorbing f…
Galactocentric Distance with the Optical Gravitational Lensing Experiment and HIPPARCOS Red Clump Stars
Paczyński, Bohdan; Stanek, Krzysztof Z.
We compare red clump stars with parallaxes known to better than 10% in the Hipparcos catalog and corrected for interstellar extinction with the OGLE red clump stars in Baade's Window, also corrected for interstellar extinction. There are ~600 and ~10,000 such stars in the two data sets, respectively. We find empirically that the average I-band mag…
Energy Distribution of Heating Processes in the Quiet Solar Corona
Krucker, Säm; Benz, Arnold O.
We have determined the variations in the emission measure of the solar corona using EUV Imaging Telescope/Solar and Heliospheric Observatory observations of iron lines in a quiet region of the Sun. The emission measure is found to vary significantly in at least 85% of all the pixels within 42 minutes. The variations are interpreted as heating even…
An Edge-On Circumstellar Disk in the Young Binary System HK Tauri
Ménard, François; Krist, John E.; Stapelfeldt, Karl R. +3 more
Hubble Space Telescope (HST) images of HK Tauri reveal that the companion star in this 2.4" (340 AU) pre-main-sequence binary system is an entirely nebulous object at visual wavelengths. HK Tau/c appears as two elongated reflection nebulosities separated by a dark lane. Near-infrared adaptive optics observations made at the Canada-France-Hawaii Te…
Improved Evidence for a Black Hole in M32 from HST/FOS Spectra. II. Axisymmetric Dynamical Models
van der Marel, Roeland P.; Rix, Hans-Walter; de Zeeuw, P. Tim +1 more
Axisymmetric dynamical models are constructed for the E3 galaxy M32 to interpret high spatial resolution stellar kinematical data obtained with the Hubble Space Telescope (HST). Models are studied with two-integral, f(E, Lz), phase-space distribution functions and with fully general three-integral distribution functions. The latter are …
Multiwavelength Observations of a Dramatic High-Energy Flare in the Blazar 3C 279
Maraschi, L.; Ghisellini, G.; Pian, E. +69 more
The blazar 3C 279, one of the brightest identified extragalactic objects in the γ-ray sky, underwent a large (factor of ~10 in amplitude) flare in γ-rays toward the end of a 3 week pointing by Compton Gamma Ray Observatory (CGRO), in 1996 January-February. The flare peak represents the highest γ-ray intensity ever recorded for this object. During …