Search Publications
Coronal Mass Ejections and Forbush Decreases
Cane, Hilary V.
Coronal Mass Ejections (CMEs) are plasma eruptions from the solar atmosphere involving previously closed field regions which are expelled into the interplanetary medium. Such regions, and the shocks which they may generate, have pronounced effects on cosmic ray densities both locally and at some distance away. These energetic particle effects can …
Dynamic Variations at the Base of the Solar Convection Zone
Thompson, M. J.; Howe, R.; Hill, F. +5 more
We have detected changes in the rotation of the sun near the base of its convective envelope, including a prominent variation with a period of 1.3 years at low latitudes. Such helioseismic probing of the deep solar interior has been enabled by nearly continuous observation of its oscillation modes with two complementary experiments. Inversion of t…
Solar wind observations over Ulysses' first full polar orbit
Balogh, A.; McComas, D. J.; Goldstein, B. E. +7 more
This study examines solar wind plasma and magnetic field observations from Ulysses' first full polar orbit in order to characterize the high-latitude solar wind under conditions of decreasing and low solar activity. By comparing observations taken over nearly all heliolatitudes and two different intervals covering the same radial distances, we are…
Multiwavelength Observations of Dusty Star Formation at Low and High Redshift
Steidel, Charles C.; Adelberger, Kurt L.
If high-redshift galaxies resemble rapidly star-forming galaxies in the local universe, most of the luminosity produced by their massive stars will have been absorbed by dust and reradiated as far-infrared photons that cannot be detected with existing facilities. This paper examines what can be learned about high-redshift star formation from the s…
Distances, Ages, and Epoch of Formation of Globular Clusters
Fusi Pecci, Flavio; Carretta, Eugenio; Clementini, Gisella +1 more
We review the results on distances and absolute ages of Galactic globular clusters (GCs) obtained after the release of the Hipparcos catalog. Several methods aimed at the definition of the Population II local distance scale are discussed, and their results compared, exploiting new results for RR Lyraes in the Large Magellanic Cloud (LMC). We find …
An Inventory of Interstellar Ices toward the Embedded Protostar W33A
van Dishoeck, E. F.; Whittet, D. C. B.; Schutte, W. A. +8 more
This paper presents, for the first time, a complete 2.4-25 µm spectrum of the dust-embedded young stellar object W33A. The spectrum was obtained with the Short Wavelength Spectrometer of the Infrared Space Observatory at a mean resolving power of ~750. The spectrum displays deep H2O ice and silicate absorptions centered at 3.0 and…
The SOLAR2000 empirical solar irradiance model and forecast tool
Floyd, L.; Viereck, R.; Woods, T. +5 more
SOLAR2000 is a collaborative project for accurately characterizing solar irradiance variability across the spectrum. A new image- and full-disk proxy empirical solar irradiance model, SOLAR2000, is being developed that is valid in the spectral range of 1-1,000,000 nm for historical modeling and forecasting throughout the solar system. The overarch…
Revision of the initial-to-final mass relation
Weidemann, V.
The initial-to final mass relation is revised in view of new theoretical and observational data. Recent stellar evolution models predict core masses at the beginning of the thermally pulsing asymptotic giant branch which practically coincide with final white dwarf masses derived for NGC 3532 and the binary white dwarf PG 0922+162. The Hyades white…
Deep galaxy counts, extragalactic background light and the stellar baryon budget
Madau, Piero; Pozzetti, Lucia
We assess the constraints imposed by the observed extragalactic background light (EBL) on the cosmic history of star formation and the stellar-mass density today. The logarithmic slope of the galaxy number-magnitude relation from the Southern Hubble Deep Field imaging survey is flatter than 0.4 in all seven UBVIJHK optical bandpasses, i.e. the lig…
NGC 6153: a super-metal-rich planetary nebula?
Barlow, M. J.; Cohen, M.; Liu, X. -W. +3 more
We have obtained deep optical spectra of the planetary nebula NGC 6153, both along its minor axis and by uniformly scanning a long slit across the whole nebula. The scanned spectra, when combined with the nebular total Hβ flux, yield integrated fluxes for all the lines (~400) in our spectra, which are rich in strong recombination lines from C, N, …