Search Publications
Hubble Space Telescope Observations of Heavy Elements in Metal-Poor Galactic Halo Stars
Beers, Timothy C.; Truran, James W.; Burles, Scott +6 more
We present new abundance determinations of neutron-capture elements Ge, Zr, Os, Ir, and Pt in a sample of 11 metal-poor (-3.1<=[Fe/H]<=-1.6) Galactic halo giant stars, based on Hubble Space Telescope UV and Keck I optical high-resolution spectroscopy. The stellar sample is dominated by r-process-rich stars such as the well-studied CS 22892-0…
Black Hole Masses and Host Galaxy Evolution of Radio-Loud Active Galactic Nuclei
van der Marel, Roeland P.; Urry, C. Megan; Lira, Paulina +2 more
We report stellar velocity dispersion measurements for a sample of 28 active galactic nucleus (AGN) host galaxies, including our previous work. Using the mass-dispersion (M•-σ) and the fundamental plane relations, we estimate the black hole mass for a sample of 66 BL Lac objects and investigate the role of black hole mass in the energet…
Seismic Emission from the Solar Flares of 2003 October 28 and 29
Lindsey, C.; Donea, A. -C.
We report the detection of seismic waves emitted from powerful solar flares that occurred in NOAA Active Region 10486 on 2003 October 28 and 29. We used helioseismic holography to image the seismic sources of the waves. This technique was previously used to image the source of seismic emission from the large solar flare of 1996 July 9. Egression p…
Helioseismic Determination of the Solar Rotation Axis
Giles, P.; Beck, J. G.
Time-distance helioseismology analysis of Dopplergrams from the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observatory spacecraft provides a very accurate measurement of meridional flows. This shows a sinusoidal variation with a period of 1 yr and was identified by P. Giles to be due to an error in the determination of…
The Evolution of Reconnection along an Arcade of Magnetic Loops
Benz, Arnold O.; Grigis, Paolo C.
RHESSI observations of a solar flare showing continuous motions of double hard X-ray sources interpreted as footpoints of magnetic loops are presented. The temporal evolution shows many distinct emission peaks of duration of some tens of seconds (``elementary flare bursts''). Elementary flare bursts have been interpreted as instabilities or oscill…
The First Giant Flare from SGR 1806-20: Observations Using the Anticoincidence Shield of the Spectrometer on INTEGRAL
Götz, D.; Mereghetti, S.; von Kienlin, A. +4 more
A giant flare from the soft gamma-ray repeater SGR 1806-20 has been discovered with the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) on 2004 December 27 and detected by many other satellites. This tremendous outburst, the first one observed from this source, was a hundred times more powerful than the two giant flares previously obser…
Statistical Distributions of Speeds of Coronal Mass Ejections
Yurchyshyn, V.; Wang, H.; Gopalswamy, N. +2 more
We studied the distribution of plane-of-sky speeds determined for 4315 coronal mass ejections (CMEs) detected by the Large Angle and Spectrometric Coronagraph Experiment on board the Solar and Heliospheric Observatory (SOHO LASCO). We found that the speed distributions for accelerating and decelerating events are nearly identical and to a good app…
Spitzer and Hubble Space Telescope Constraints on the Physical Properties of the z~7 Galaxy Strongly Lensed by A2218
Kneib, J. -P.; Le Floc'h, E.; Dole, H. +10 more
We report the detection of a z~7 galaxy strongly lensed by the massive galaxy cluster A2218 (z=0.175) at 3.6 and 4.5 µm using the Spitzer Space Telescope and at 1.1 µm using the Hubble Space Telescope. The new data indicate a refined photometric redshift in the range of 6.6-6.8 depending on the presence of Lyα emission. The spectral en…
Giant Molecular Clouds in M64
Blitz, L.; Rosolowsky, E.
We investigate the properties of giant molecular clouds (GMCs) in the molecule-rich galaxy M64 (NGC 4826). In M64, the mean surface density of molecular gas is 2N(H2)~1022 cm-2 over a 2 kpc region, equal to the surface densities of individual GMCs in the Milky Way. We observed the J=1-->0 transitions of CO,
Hubble Space Telescope and Ground-based Observations of SN 1993J and SN 1998S: CNO Processing in the Progenitors
Filippenko, Alexei V.; Pun, C. S. J.; Garnavich, Peter +13 more
Ground-based and Hubble Space Telescope observations are presented for SN 1993J and SN 1998S. SN 1998S shows strong, relatively narrow circumstellar emission lines of N III-V and C III-IV, as well as broad lines from the ejecta. Both the broad ultraviolet and optical lines in SN 1998S indicate an expansion velocity of ~7000 km s-1. The …