Institution
Jet Propulsion Laboratory
Facility•La Cañada Flintridge, California, United States•
About: Jet Propulsion Laboratory is a facility organization based out in La Cañada Flintridge, California, United States. It is known for research contribution in the topics: Mars Exploration Program & Telescope. The organization has 8801 authors who have published 14333 publications receiving 548163 citations. The organization is also known as: JPL & NASA JPL.
Topics: Mars Exploration Program, Telescope, Galaxy, Coronagraph, Planet
Papers published on a yearly basis
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TL;DR: In this article, the authors studied the relation between the internal structure of early-type galaxies and their environment using 70 strong gravitational lenses from the SLACS Survey and found that the average overdensity is somewhat larger than unity.
Abstract: We study the relation between the internal structure of early-type galaxies and their environment using 70 strong gravitational lenses from the SLACS Survey. The Sloan Digital Sky Survey (SDSS) database is used to determine two measures of overdensity of galaxies around each lens-the projected number density of galaxies inside the tenth nearest neighbor ({sigma}{sub 10}) and within a cone of radius one h{sup -1} Mpc (D {sub 1}). Our main results are as follows. (1) The average overdensity is somewhat larger than unity, consistent with lenses preferring overdense environments as expected for massive early-type galaxies (12/70 lenses are in known groups/clusters). (2) The distribution of overdensities is indistinguishable from that of 'twin' nonlens galaxies selected from SDSS to have the same redshift and stellar velocity dispersion {sigma}{sub *}. Thus, within our errors, lens galaxies are an unbiased population, and the SLACS results can be generalized to the overall population of early-type galaxies. (3) Typical contributions from external mass distribution are no more than a few percent in local mass density, reaching 10-20% ({approx}0.05-0.10 external convergence) only in the most extreme overdensities. (4) No significant correlation between overdensity and slope of the mass-density profile of the lens galaxies is found. (5)more » Satellite galaxies (those with a more luminous companion) have marginally steeper mass-density profiles (as quantified by f {sub SIE} = {sigma}{sub *}/{sigma}{sub SIE} = 1.12 {+-} 0.05 versus 1.01 {+-} 0.01) and smaller dynamically normalized mass enclosed within the Einstein radius ({delta}log M {sub Ein}/M {sub dim} differs by -0.09 {+-} 0.03 dex) than central galaxies (those without). This result suggests that tidal stripping may affect the mass structure of early-type galaxies down to kpc scales probed by strong lensing, when they fall into larger structures.« less
131 citations
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Lunar and Planetary Institute1, Jet Propulsion Laboratory2, Geological Survey of Canada3, United States Geological Survey4, Cornell University5, British Antarctic Survey6, Oregon State University7, Goddard Space Flight Center8, Arizona State University9, Lawrence Livermore National Laboratory10, University of Paris11, European Space Agency12, Ames Research Center13, University of Alaska Fairbanks14, Case Western Reserve University15, University of Virginia16, California Institute of Technology17, University of Toledo18, Oklahoma State University–Stillwater19, University of Bristol20, University of California, Berkeley21, University of Nebraska–Lincoln22, Technical University of Denmark23, University of Arizona24, Ohio State University25, Alfred Wegener Institute for Polar and Marine Research26, University of Washington27, Massachusetts Institute of Technology28
TL;DR: The current state of Mars polar research is assessed, the key questions that motivate the exploration of the polar regions are identified, the extent to which current missions will address these questions are discussed, and what additional capabilities and investigations may be required to address the issues that remain outstanding are speculated.
131 citations
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Max Planck Society1, University of Winnipeg2, Free University of Berlin3, Planetary Science Institute4, University of California, Los Angeles5, Johns Hopkins University6, Royal Ontario Museum7, Braunschweig University of Technology8, Brown University9, Jet Propulsion Laboratory10, Lunar and Planetary Institute11, Georgia Institute of Technology12
TL;DR: It is concluded that Ceres must have accreted material from beyond the ‘snow line’, which is the distance from the Sun at which water molecules condense, and is consistent with hydrated magnesium sulfates mixed with dark background material.
Abstract: The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense.
131 citations
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TL;DR: It is shown that the region of the belt around Magnya is densely filled by mean-motion resonances, generating slow orbital diffusion processes and providing a potential mechanism for removing other basaltic fragments that may have been created on the same parent body as MagnyA.
Abstract: Visible and near-infrared spectroscopic observations of the asteroid 1459 Magnya indicate that it has a basaltic surface. Magnya is at 3.15 astronomical units (AU) from the sun and has no known dynamical link to any family, to any nearby large asteroid, or to asteroid 4 Vesta at 2.36 AU, which is the only other known large basaltic asteroid. We show that the region of the belt around Magnya is densely filled by mean-motion resonances, generating slow orbital diffusion processes and providing a potential mechanism for removing other basaltic fragments that may have been created on the same parent body as Magnya. Magnya may represent a rare surviving fragment from a larger, differentiated planetesimal that was disrupted long ago.
131 citations
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TL;DR: Ozone losses could approach 50 percent if regeneration of nitrogen dioxide were inhibited by irreversible removal of nitrogen oxides (denitrification), as presently observed in the Antarctic, or without denitrification if inorganic chlorine concentrations were to double.
Abstract: In situ measurements of chlorine monoxide, bromine monoxide, and ozone are extrapolated globally, with the use of meteorological tracers, to infer the loss rates for ozone in the Arctic lower stratosphere during the Airborne Arctic Stratospheric Expedition II (AASE II) in the winter of 1991-1992. The analysis indicates removal of 15 to 20 percent of ambient ozone because of elevated concentrations of chlorine monoxide and bromine monoxide. Observations during AASE II define rates of removal of chlorine monoxide attributable to reaction with nitrogen dioxide (produced by photolysis of nitric acid) and to production of hydrochloric acid. Ozone loss ceased in March as concentrations of chlorine monoxide declined. Ozone losses could approach 50 percent if regeneration of nitrogen dioxide were inhibited by irreversible removal of nitrogen oxides (denitrification), as presently observed in the Antarctic, or without denitrification if inorganic chlorine concentrations were to double.
131 citations
Authors
Showing all 9033 results
Name | H-index | Papers | Citations |
---|---|---|---|
B. P. Crill | 148 | 486 | 111895 |
George Helou | 144 | 662 | 96338 |
H. K. Eriksen | 141 | 474 | 104208 |
Charles R. Lawrence | 141 | 528 | 104948 |
W. C. Jones | 140 | 395 | 97629 |
Gianluca Morgante | 138 | 478 | 98223 |
Jean-Paul Kneib | 138 | 805 | 89287 |
Kevin M. Huffenberger | 138 | 402 | 93452 |
Robert H. Brown | 136 | 1174 | 79247 |
Federico Capasso | 134 | 1189 | 76957 |
Krzysztof M. Gorski | 132 | 380 | 105912 |
Olivier Doré | 130 | 427 | 104737 |
Mark E. Thompson | 128 | 527 | 77399 |
Clive Dickinson | 123 | 501 | 80701 |
Daniel Stern | 121 | 788 | 69283 |