Search Publications
On the sources of fast and slow solar wind
Schwadron, N. A.; Landi, E.; Feldman, U.
The slow speed solar wind as measured at the Earth orbit and beyond is characterized by its velocity of ≃400 km s-1, by its coronal composition and by its frozen-in temperature (from carbon charge-states) of 1.4-1.6 × 106 K. In contrast the fast speed solar wind is characterized by its velocity of ≃750 km s-1, its …
Cosmological weak lensing with the HST GEMS survey
Bell, Eric F.; Wisotzki, Lutz; Wolf, Christian +16 more
We present our cosmic shear analysis of GEMS, one of the largest wide-field surveys ever undertaken by the Hubble Space Telescope. Imaged with the Advanced Camera for Surveys (ACS), GEMS spans 795 arcmin2 in the Chandra Deep Field South. We detect weak lensing by large-scale structure in high-resolution F606W GEMS data from ~60 resolved…
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…
The Ice Survey Opportunity of ISO
Dartois, Emmanuel
The instruments on board the Infrared Space Observatory have for the first time allowed a complete low (PHOT, CVF) to medium resolution (SWS) spectroscopic harvest, from 2.5 to 45 µm, of interstellar dust. Amongst the detected solids present in starless molecular clouds surrounding recently born stellar and still embedded objects or products…
New constraints on modified Newtonian dynamics from galaxy clusters
Silk, Joseph; Pointecouteau, Etienne
We revisit the application of modified Newtonian dynamics (MOND) to galaxy clusters. We confront the high-quality X-ray data for eight clusters of galaxies observed by the XMM-Newton satellite with the predictions of MOND. We obtain a ratio of the MOND dynamical mass to the baryonic mass of Mm/Mb= 4.94 +/- 0.50 in the outer p…
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…
A Study of Edge-On Galaxies with the Hubble Space Telescope Advanced Camera for Surveys. II. Vertical Distribution of the Resolved Stellar Population
de Jong, Roelof S.; Seth, Anil C.; Dalcanton, Julianne J.
We analyze the vertical distribution of the resolved stellar populations in six low-mass (Vmax=67-131 km s-1), edge-on, spiral galaxies observed with the Hubble Space Telescope Advanced Camera for Surveys. In each galaxy we find evidence for an extraplanar stellar component extending up to 15 scale heights (3.5 kpc) above the…
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 …
Narrow Iron Kα Lines in Active Galactic Nuclei: Evolving Populations?
Zhou, Xin-Lin; Wang, Jian-Min
We assemble a sample consisting of 66 active galactic nuclei (AGNs) from the literature and from the XMM-Newton archive in order to investigate the origin of the 6.4 keV narrow iron Kα line (NIKAL). The X-ray Baldwin effect of the NIKAL is confirmed in this sample. We find that the equivalent width (EW) of the NIKAL is more strongly inversely corr…