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SUMER Measurements of Nonthermal Motions: Constraints on Coronal Heating Mechanisms
Chae, Jongchul; Schühle, Udo; Lemaire, Philippe
We have determined nonthermal velocities in the quiet Sun at temperatures between 104 K and 2 × 106 K by measuring the widths of a number of EUV and far-ultraviolet (FUV) lines taken with SUMER on board the SOHO spacecraft. The broadenings owing to the SUMER instrument and the finite opacity in each line have been carefully e…
Metal-rich globular clusters in the galactic disk: new age determinations and the relation to halo clusters
Salaris, M.; Weiss, A.
New age determinations of the galactic disk globular clusters 47 Tuc, M 71 and NGC 6352 have been performed with our up-to-date alpha -enhanced stellar models. We find that all three clusters are about 9.2 Gyr old and therefore coeval with the oldest disk white dwarfs. Several arguments are presented which indicate that the initial helium content …
The Color-Magnitude Relation in CL 1358+62 at Z = 0.33: Evidence for Significant Evolution in the S0 Population
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +3 more
We use a large, multicolor mosaic of HST WFPC2 images to measure the colors and morphologies of 194 spectroscopically confirmed members of the rich galaxy cluster CL 1358+62 at z = 0.33. We study the color-magnitude (CM) relation as a function of radius in the cluster to a limit of 4.6 arcmin from the center, equivalent to 1.6 h-15…
Externally Illuminated Young Stellar Environments in the Orion Nebula: Hubble Space Telescope Planetary Camera and Ultraviolet Observations
Johnstone, Doug; Bally, John; Sutherland, Ralph S. +1 more
We present new 0.05" resolution (22 AU) narrowband Hubble Space Telescope Planetary Camera images of externally illuminated young stellar objects embedded in the Orion Nebula. We also present 0.02" resolution (9 AU) UV images of seven externally illuminated protostellar environments and the first UV spectra that cover the spectral range between 14…
Radio Emission from Galaxies in the Hubble Deep Field
Fomalont, E. B.; Windhorst, R. A.; Richards, E. A. +2 more
We report on sensitive radio observations made with the VLA at 8.5 GHz centered on the Hubble Deep Field (HDF). We collected data in the A, CnB, C, DnC, and D configurations corresponding to angular resolutions ranging from 0.3" to 10". We detected 29 radio sources in a complete sample within 4.6‧ of the HDF center and above a flux density limit o…
The distribution of nearby stars in phase space mapped by Hipparcos. I. The potential well and local dynamical mass
Pichon, C.; Creze, M.; Chereul, E. +1 more
Hipparcos data provide the first, volume limited and absolute magnitude limited homogeneous tracer of stellar density and velocity distributions in the solar neighbourhood. The density of A-type stars more luminous than M_v=2. 5 can be accurately mapped within a sphere of 125 pc radius, while proper motions in galactic latitude provide the vertica…
The TYCHO Reference Catalogue
Makarov, V. V.; Lindegren, L.; Bastian, U. +5 more
The Tycho Reference Catalogue\ (TRC) contains high-quality positions and proper motions for 990 182\ stars of the Tycho Catalogue. The proper motions were derived from Tycho positions and Astrographic Catalogue\ positions reduced to the Hipparcos system. The median accuracy of the TRC position components is 40 mas at J1991.25. The median precision…
First Solar EUV Irradiances Obtained from SOHO by the CELIAS/SEM
Wurz, P.; Klecker, B.; Möbius, E. +10 more
The first results obtained with the Solar EUV Monitor (SEM), part of the Charge, Element, and Isotope Analysis System (CELIAS) instrument, aboard the SOlar and Heliospheric Observatory (SOHO) satellite are presented. The instrument monitors the full-disk absolute value of the solar Heii irradiance at 30.4 nm, and the full-disk absolute solar irrad…
Minimum and Maximum Variance Analysis
Sonnerup, Bengt U. Ö.; Scheible, Maureen
Faint Submillimeter Galaxies: Hubble Space Telescope Morphologies and Colors
Kneib, J. -P.; Ivison, R. J.; Smail, Ian +1 more
We present deep optical imaging from the Hubble Space Telescope (HST) and from the ground for galaxies selected from the first submillimeter survey of the distant universe. Our survey comprises 850 µm continuum maps of seven massive lensing clusters and covers a total area of 0.01 deg2 to 1 σ noise levels of <=2 mJy beam-1…