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Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Halbwachs, J. -L.; Arenou, F.; Rolland, L. +11 more
Radial velocities have been determined for a sample of 2930 B2-F5 stars, 95% observed by the Hipparcos satellite in the north hemisphere and 80% without reliable radial velocity up to now. Observations were obtained at the Observatoire de Haute Provence with a dispersion of 80 Ä,mm(-1) with the aim of studying stellar and galactic dynamics. Radial…
HIPPARCOS distance calibrations for 9 open clusters
van Leeuwen, Floor
Parallaxes have been determined for 9 nearby open clusters in order to derive a composite, age resolved, HR diagram. An age-luminosity relation was found to exist for main-sequence stars. A suggested 1 mas error in the Hipparcos parallax for the Pleiades, to explain the difference with the ground-based photometric distance estimate, seems unlikely…
Blue Straggler Stars: The Spectacular Population in M80
Ferraro, Francesco R.; Paltrinieri, Barbara; Dorman, Ben +1 more
Using Hubble Space Telescope WFPC2 observations in two ultraviolet (UV) filters (F225W and F336W) of the central region of the high-density Galactic globular cluster (GGC) M80, we have identified 305 blue straggler stars (BSS), which represents the largest and most concentrated population of BSS ever observed in a GGC. We also identify the largest…
The Double Nucleus and Central Black Hole of M31
Kormendy, John; Bender, Ralf
New spectroscopy of M31 supports Tremaine's model in which both nuclei are parts of a single eccentric disk of stars orbiting the black hole (BH). The kinematics and Hubble Space Telescope photometry are used to measure the offset of the BH from the center of mass. This confirms that the BH mass is ~3×107 Msolar by a techniqu…
Acceleration of the fast solar wind by the emergence of new magnetic flux
Schwadron, N. A.; Zurbuchen, T. H.; Fisk, L. A.
Recent observations have shown that small magnetic loops are continuously emerging within supergranules in the solar photosphere. The subsequent reconnection of this emerging flux with field lines which open into the corona should define the Poynting's vector and mass flux into the corona. These two quantities uniquely determine the final energy f…
Discovery of an Extremely Young Accreting Protostar in Taurus
Motte, F.; André, P.; Bacmann, A.
We report the discovery of a new, very young accreting class 0 protostar in the southern part of the Taurus molecular cloud. This object, designated by IRAM 04191+1522, coincides with a cold (T~12 K) dust continuum condensation found at 1.3 mm with the IRAM 30 m telescope ~1' southwest of the class I infrared source IRAS 04191+1523. Although IRAM …
Velocity distribution of stars in the solar neighbourhood
Cottrell, P. L.; Hearnshaw, J. B.; Skuljan, J.
A two-dimensional velocity distribution in the UV plane has been obtained for stars in the solar neighbourhood, using Hipparcos astrometry for over 4000 `survey' stars with parallaxes greater than 10mas and radial velocities found in the Hipparcos Input Catalogue. In addition to the already known grouping characteristics (field stars plus young mo…
A Candidate Substellar Companion to CD -33°7795 (TWA 5)
Schneider, Glenn; Hines, Dean C.; Terrile, Richard J. +12 more
We present the discovery of a candidate substellar object in a survey of young stars in the solar vicinity using the sensitivity and spatial resolution afforded by the NICMOS coronagraph on the Hubble Space Telescope. The H=12.1 mag object was discovered approximately 2" from the TW Hydrae association member CD -33°7795 (TWA 5), and the photometry…
2.4-197 mu m spectroscopy of OH/IR stars: the IR characteristics of circumstellar dust in O-rich environments
Waters, L. B. F. M.; Omont, A.; Barlow, M. J. +4 more
Infrared spectra of a number of evolved O-rich stars have been obtained with the Short- and Long- Wavelength spectrometers on board the Infrared Space Observatory. The very broad wavelength coverage (2.4-197 mu m) obtained by combining observations made with the two spectrometers includes practically all of the flux emitted by the sources, and all…
Hubble Space Telescope Imaging of the CFRS and LDSS Redshift Surveys. III. Field Elliptical Galaxies at 0.2<z<1.0
Brinchmann, Jarle; Broadhurst, Tom; Glazebrook, K. +9 more
Two-dimensional surface photometry has been performed on a magnitude-limited sample of 46 field galaxies that are classified as ellipticals based on two-dimensional fitting of their luminosity profiles using Hubble Space Telescope imaging. These galaxies are described well by a de Vaucouleurs R1/4 profile. The sample was selected from t…