Search Publications
HIPPARCOS photometry of Herbig Ae/Be stars
de Winter, D.; van den Ancker, M. E.; Tjin A Djie, H. R. E.
The photometric behaviour of a sample of 44 Herbig Ae/Be (HAeBe) candidate stars was studied using a uniform set of optical photometry obtained by the Hipparcos mission. Astrophysical parameters (distance, temperature, luminosity, mass, age) of this sample of stars were derived as well by combining the astrometric data provided by Hipparcos with d…
UVCS/SOHO Empirical Determinations of Anisotropic Velocity Distributions in the Solar Corona
Romoli, M.; Raymond, J. C.; Naletto, G. +28 more
We present a self-consistent empirical model for several plasma parameters of a polar coronal hole near solar minimum, derived from observations with the Solar and Heliospheric Observatory Ultraviolet Coronagraph Spectrometer. The model describes the radial distribution of density for electrons, H0, and O5+ and the outflow ve…
Photoevaporation of Disks and Clumps by Nearby Massive Stars: Application to Disk Destruction in the Orion Nebula
Johnstone, Doug; Bally, John; Hollenbach, David
We present a model for the photoevaporation of circumstellar disks or dense clumps of gas by an external source of ultraviolet radiation. Our model includes the thermal and dynamic effects of 6-13.6 eV far-ultraviolet (FUV) photons and Lyman continuum EUV photons incident upon disks or clumps idealized as spheres of radius rd and enclos…
Auroral radio emissions at the outer planets: Observations and theories
Zarka, Philippe
We review both observational and theoretical aspects of the generation of auroral radio emissions at the outer planets, trying to organize the former in a coherent frame set by the latter. Important results have been obtained in the past few years on these radio emissions at the five magnetized planets, from the observations of Ulysses at Jupiter …
How uncertain are solar neutrino predictions?
Basu, Sarbani; Pinsonneault, M. H.; Bahcall, John N.
Solar neutrino fluxes and sound speeds are calculated using a systematic reevaluation of nuclear fusion rates. The largest uncertainties are identified and their effects on the solar neutrino fluxes are estimated.
ICCD Speckle Observations of Binary Stars. XIX. an Astrometric/Spectroscopic Survey of O Stars
Gies, Douglas R.; Bagnuolo, William G., Jr.; Mason, Brian D. +3 more
We present the results of a speckle interferometric survey made with the CHARA speckle camera and 4 m-class telescopes of Galactic O-type stars with V < 8. We can detect with the speckle camera binaries in the angular separation range 0.035" < rho < 1.5" with Deltam < 3, and we have discovered 15 binaries among 227 O-type systems. We c…
A hyperluminous galaxy at z=2.8 found in a deep submillimetre survey
Kneib, J. -P.; Ivison, R. J.; Smail, Ian +5 more
We present a detailed study of SMM02399-0136, a hyperluminous, active galaxy selected from a submm survey of the distant Universe. This galaxy is the brightest source in the fields of six rich, lensing clusters, with a total area of 0.01deg^2, that we have mapped with a sensitivity of ~2mJybeam^-1 at 850mum. We identify a compact optical counterpa…
Distance to M31 with the Hubble Space Telescope and HIPPARCOS Red Clump Stars
Garnavich, P. M.; Stanek, K. Z.
Following the approach by Paczyński & Stanek, we compare the red clump stars with parallaxes known to better than 10% in the Hipparcos catalog with the red clump stars observed in three fields in M31 using the Hubble Space Telescope. There are ~600 and ~6300 such stars in the two data sets, respectively. The local red clump luminosity function…
The Definitive Abundance of Interstellar Oxygen
Meyer, David M.; Jura, M.; Cardelli, Jason A.
Using the Goddard High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope, we have obtained high signal-to-noise (S/N) ratio echelle observations of the weak interstellar O I λ1356 absorption toward the stars γ Cas, ɛ Per, δ Ori, ɛ Ori, 15 Mon, τ CMa, and γ Ara. In combination with previous GHRS measurements in six other sight lines…
Infrared Observations of Nebular Emission Lines from Galaxies at Z ~= 3
Dickinson, Mark; Giavalisco, Mauro; Pettini, Max +3 more
We present the first results from a program of near-infrared spectroscopy aimed at studying the familiar rest-frame optical emission lines from the H II regions of Lyman break galaxies at z ~= 3. By targeting redshifts that bring the lines of interest into gaps between the strong OH sky emission, we have been successful in detecting Balmer and [O …