51,512 research outputs found
DIRBE Minus 2MASS: Confirming the CIRB in 40 New Regions at 2.2 and 3.5 Microns
With the release of the 2MASS All-Sky Point Source Catalog, stellar fluxes
from 2MASS are used to remove the contribution due to Galactic stars from the
intensity measured by DIRBE in 40 new regions in the North and South Galactic
polar caps. After subtracting the interplanetary and Galactic foregrounds, a
consistent residual intensity of 14.69 +/- 4.49 kJy/sr at 2.2 microns is found.
Allowing for a constant calibration factor between the DIRBE 3.5 microns and
the 2MASS 2.2 microns fluxes, a similar analysis leaves a residual intensity of
15.62 +/- 3.34 kJy/sr at 3.5 microns. The intercepts of the DIRBE minus 2MASS
correlation at 1.25 microns show more scatter and are a smaller fraction of the
foreground, leading to a still weak limit on the CIRB of 8.88 +/- 6.26 kJy/sr
(1 sigma).Comment: 25 pages LaTeX, 10 figures, 5 tables; Version accepted by the ApJ.
Includes minor changes to the text including further discussion of zodiacal
light issues and the allowance for variable stars in computing uncertainties
in the stellar contribution to the DIRBE intensitie
Bedrock geology of the northern Columbia Plateau and adjacent areas
The Columbia Plateau is surrounded by a complex assemblage of highly deformed Precambrian to lower Tertiary continental and oceanic rocks that reflects numerous episodes of continental accretion. The plateau itself is comprised of the Columbia River basalt group formed between about 16.5 x 1 million years B.P. and 6 x 1 million years B.P. Eruptions were infrequent between about 14 and 6 x 1 million years B.P., allowing time for erosion and deformation between successive outpourings. The present-day courses of much of the Snake River, and parts of the Columbia River, across the plateau date from this time. Basalt produced during this waning activity is more heterogeneous chemically and isotopically than older flows, reflecting its prolonged period of volcanism
I would have been/ could be amazing: a social justice oriented visual art rejoinder to whole earth?
The art pieces shown at the conference were informed by current and significant local, national and international contexts, including the continuing so called ‘migrant crisis’ and the effects of on-going financial cuts to mental health services (Foley, 2013; Mind, 2014); issues that the art psychotherapists see as points of struggle but that might otherwise be imagined and realised as opportunities, through radical praxis, for sustainable socially just futures.
Summary of participatory content. Each artist provided a reflective piece of writing to accompany their art work included in the exhibition that briefly explained to viewers the thinking and rationale behind the work. Below is a sample of each artist’s contribution with title, media and reflective description of work. Art psychotherapists were available at the exhibition to discuss the art work and motivations behind it with conference participants, which enhanced the contributions of both parties
OEXP Analysis Tools Workshop
This publication summarizes the software needs and available analysis tools presented at the OEXP Analysis Tools Workshop held at the NASA Langley Research Center, Hampton, Virginia on June 21 to 22, 1988. The objective of the workshop was to identify available spacecraft system (and subsystem) analysis and engineering design tools, and mission planning and analysis software that could be used for various NASA Office of Exploration (code Z) studies, specifically lunar and Mars missions
Orbital thermal analysis of lattice structured spacecraft using color video display techniques
A color video display technique is demonstrated as a tool for rapid determination of thermal problems during the preliminary design of complex space systems. A thermal analysis is presented for the lattice-structured Earth Observation Satellite (EOS) spacecraft at 32 points in a baseline non Sun-synchronous (60 deg inclination) orbit. Large temperature variations (on the order of 150 K) were observed on the majority of the members. A gradual decrease in temperature was observed as the spacecraft traversed the Earth's shadow, followed by a sudden rise in temperature (100 K) as the spacecraft exited the shadow. Heating rate and temperature histories of selected members and color graphic displays of temperatures on the spacecraft are presented
Recommended from our members
Stochastic modelling of the effects of interdependencies between critical infrastructure
An approach to Quantitative Interdependency Analysis, in the context of Large Complex Critical Infrastructures, is presented in this paper. A Discrete state–space, Continuous–time, Stochastic Process models the operation of critical infrastructure, taking interdependencies into account. Of primary interest are the implications of both model detail (that is, level of model abstraction) and model parameterisation for the study of dependencies. Both of these factors are observed to affect the distribution of cascade–sizes within and across infrastructure
Revision of Earth-sized Kepler Planet Candidate Properties with High Resolution Imaging by Hubble Space Telescope
We present the results of our Hubble Space Telescope program and describe how
our analysis methods were used to re-evaluate the habitability of some of the
most interesting Kepler planet candidates. Our program observed 22 Kepler
Object of Interest (KOI) host stars, several of which were found to be multiple
star systems unresolved by Kepler. We use our high-resolution imaging to
spatially resolve the stellar multiplicity of Kepler-296, KOI-2626, and
KOI-3049, and develop a conversion to the Kepler photometry (Kp) from the F555W
and F775W filters on WFC3/UVIS. The binary system Kepler-296 (5 planets) has a
projected separation of 0.217" (80AU); KOI-2626 (1 planet candidate) is a
triple star system with a projected separation of 0.201" (70AU) between the
primary and secondary components and 0.161" (55AU) between the primary and
tertiary; and the binary system KOI-3049 (1 planet candidate) has a projected
separation of 0.464" (225AU). We use our measured photometry to fit the
separated stellar components to the latest Victoria-Regina Stellar Models with
synthetic photometry to conclude that the systems are coeval. The components of
the three systems range from mid-K dwarf to mid-M dwarf spectral types. We
solved for the planetary properties of each system analytically and via an MCMC
algorithm using our independent stellar parameters. The planets range from
~1.6R_Earth to ~4.2R_Earth, mostly Super Earths and mini-Neptunes. As a result
of the stellar multiplicity, some planets previously in the Habitable Zone are,
in fact, not, and other planets may be habitable depending on their assumed
stellar host.Comment: 16 pages, 10 figures, ApJ, 804, 9
HD 4915: A Maunder Minimum Candidate
We study the magnetic activity cycle of HD 4915 using the \ion{Ca}{2} H \& K
emission line strengths measured by Keck I/HIRES spectrograph. The star has
been observed as a part of California Planet Search Program from 2006 to
present. We note decreasing amplitude in the magnetic activity cycle, a pattern
suggesting the star's entry into a Magnetic Grand Minimum (MGM) state,
reminiscent of the Sun's Maunder and Dalton Minima. We recommend further
monitoring of the star to confirm the grand minimum nature of the dynamo, which
would provide insight into the state of the Sun's chromosphere and the global
magnetic field during its grand minima. We also recommend continued
observations of H \& K emission lines, and ground or space based photometric
observations to estimate the sunspot coverage.Comment: To be submitted to AAS Journals; comments welcom
The dust emission of high-redshift quasars
The detection of powerful near-infrared emission in high redshift (z>5)
quasars demonstrates that very hot dust is present close to the active nucleus
also in the very early universe. A number of high-redshift objects even show
significant excess emission in the rest frame NIR over more local AGN spectral
energy distribution (SED) templates. In order to test if this is a result of
the very high luminosities and redshifts, we construct mean SEDs from the
latest SDSS quasar catalogue in combination with MIR data from the WISE
preliminary data release for several redshift and luminosity bins. Comparing
these mean SEDs with a large sample of z>5 quasars we could not identify any
significant trends of the NIR spectral slope with luminosity or redshift in the
regime 2.5 < z < 6 and 10^45 < nuL_nu(1350AA) < 10^47 erg/s. In addition to the
NIR regime, our combined Herschel and Spitzer photometry provides full infrared
SED coverage of the same sample of z>5 quasars. These observations reveal
strong FIR emission (L_FIR > 10^13 L_sun) in seven objects, possibly indicating
star-formation rates of several thousand solar masses per year. The FIR excess
emission has unusally high temperatures (T ~ 65 K) which is in contrast to the
temperature typically expected from studies at lower redshift (T ~ 45 K). These
objects are currently being investigated in more detail.Comment: 6 pages, 3 figures, to appear in the proceedings to "The Central
Kiloparsec in Galactic Nuclei (AHAR2011)", Journal of Physics: Conference
Series (JPCS), IOP Publishin
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