Search Publications
The Initial Mass Function of the Galactic Bulge down to ~0.15 Msolar
Gould, Andrew; Rich, R. Michael; Frogel, Jay A. +5 more
We present a luminosity function (LF) for lower main-sequence stars in the Galactic bulge near (l,b)=(0deg,-6deg) to J=24, corresponding to MJ~9.3. This LF is derived from Hubble Space Telescope (HST) near infrared camera and multiobject spectrometer (NICMOS) observations of a region of 22.5"x22.5", with the F110W …
Discovery of Gaseous S2 in Io's Pele Plume
Ballester, Gilda E.; McGrath, Melissa A.; Spencer, John R. +2 more
Spectroscopy of Io's Pele plume against Jupiter by the Hubble Space Telescope in October 1999 revealed absorption due to S2 gas, with a column density of 1.0 +/- 0.2 × 1016 per square centimeter, and probably also SO2 gas with a column density of 7 +/- 3 × 1016 per square centimeter. This SO2/…
Implications of the cosmic infrared background for light production and the star formation history in the Universe
Lagache, G.; Puget, J. L.; Gispert, R.
The Cosmic Background due to the integrated radiation from galaxies over the whole life of the Universe is reviewed. We find that this background is well constrained by measurements. The total power in the background is in the range 60-93 nWm-2sr-1. The data show the existence of a minimum separating the direct stellar radiat…
Ion Cyclotron Wave Dissipation in the Solar Corona: The Summed Effect of More than 2000 Ion Species
Cranmer, Steven R.
In this paper the dissipation of ion cyclotron resonant Alfvén waves in the extended solar corona is examined in detail. For the first time, the wave damping arising from more than 2000 low-abundance ion species is taken into account. Useful approximations for the computation of coronal ionization equilibria for elements heavier than nickel are pr…
Magnetic AP Stars in the Hertzsprung-Russell Diagram
Hubrig, S.; North, P.; Mathys, G.
The evolutionary state of magnetic Ap stars is rediscussed using the recently released Hipparcos data. The distribution of the magnetic Ap stars of mass below 3 Msolar in the H-R diagram differs from that of the normal stars in the same temperature range at a high level of significance. Magnetic stars are concentrated toward the center …
Weak Lensing Measurements: A Revisited Method and Application toHubble Space Telescope Images
Refregier, Alexandre; Rhodes, Jason; Groth, Edward J.
The weak distortions produced by gravitational lensing in the images of background galaxies provide a unique method to measure directly the distribution of mass in the universe. However, because the induced distortions are only of a few percent, this technique requires high-precision measurements of the lensing shear and cautious corrections for s…
The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XXV. A Recalibration of Cepheid Distances to Type IA Supernovae and the Value of the Hubble Constant
Kelson, Daniel D.; Illingworth, Garth D.; Huchra, John P. +14 more
Cepheid-based distances to seven Type Ia supernovae (SNe) host galaxies have been derived using the standard Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale pipeline. For the first time, this allows for a transparent comparison of data accumulated as part of three different HST projects: the Key Project, the Sandage et…
Si and Mn Abundances in Damped Lyα Systems with Low Dust Content
Bowen, David V.; Pettini, Max; Ellison, Sara L. +2 more
We have measured the abundances of Zn, Si, Mn, Cr, Fe, and Ni in three damped Lyα systems at redshifts zabs<=1 from high-resolution echelle spectra of QSOs recorded with the Keck I telescope. In all three cases, the abundances of Cr, Fe, and Ni relative to Zn indicate low levels of dust depletions. We propose that when the proportion…
Aspects of the mass distribution of interstellar dust grains in the solar system from in situ measurements
Krüger, H.; Grün, E.; Landgraf, M. +2 more
The in situ detection of interstellar dust grains in the solar system by the dust instruments on-board the Ulysses and Galileo spacecraft as well as the recent measurements of hyperbolic radar meteors give information on the properties of the interstellar solid particle population in the solar vicinity. Especially the distribution of grain masses …
A proper motion study of the globular cluster ω Centauri
Freeman, K. C.; van Leeuwen, F.; Le Poole, R. S. +2 more
A proper motion study is presented of the globular cluster ω Centauri. Based on 100 plates obtained with the Yale-Columbia 66 cm (26 inch) refractor, and ranging in epoch from 1931 till 1935 and 1978 till 1983, differential proper motions are obtained for 9847 stars. The limiting magnitude (photographic) is 16.0 for the centre of the cluster, 16.5…