39 research outputs found
Aspirations and common tensions : larger lessons from the third US national climate assessment
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Climatic Change 135 (2016): 187-201, doi:10.1007/s10584-015-1530-z.The Third US National Climate Assessment (NCA3) was produced by experts in response to the US Global Change Research Act of 1990. Based on lessons learned from previous domestic and international assessments, the NCA3 was designed to speak to a broad public and inform the concerns of policy- and decision-makers at different scales. The NCA3 was also intended to be the first step in an ongoing assessment process that would build the nation’s capacity to respond to climate change. This concluding paper draws larger lessons from the insights gained throughout the assessment process that are of significance to future US and international assessment designers. We bring attention to process and products delivered, communication and engagement efforts, and how they contributed to the sustained assessment. Based on areas where expectations were exceeded or not fully met, we address four common tensions that all assessment designers must confront and manage: between (1) core assessment ingredients (knowledge base, institutional set-up, principled process, and the people involved), (2) national scope and subnational adaptive management information needs, (3) scope, complexity, and manageability, and (4) deliberate evaluation and ongoing learning approaches. Managing these tensions, amidst the social and political contexts in which assessments are conducted, is critical to ensure that assessments are feasible and productive, while its outcomes are perceived as credible, salient, and legitimate
Mid-Infrared Imaging of NGC 6334 I
We present high-resolution (<0.5") mid-infrared Keck II images of individual
sources in the central region of NGC 6334 I. We compare these images to images
at a variety of other wavelengths from the near infrared to cm radio continuum
and speculate on the nature of the NGC 6334 I sources. We assert that the
cometary shape of the UCHII region here, NGC 6334 F, is due to a champagne-like
flow from a source on the edge of a molecular clump and not a due to a bow
shock caused by the supersonic motion of the UCHII region through the
interstellar medium. The mid-infrared emission in concentrated into an arc of
dust that define the boundary between the UCHII region and the molecular clump.
This dust arc contains a majority of the masers in the region. We discuss the
nature of the four near-infrared sources associated with IRS-I 1, and suggest
that one of the sources, IRS1E, is responsible for the heating and ionizing of
the UCHII region and the mid-infrared dust arc. Infrared source IRS-I 2, which
has been thought to be a circumstellar disk associated with a linear
distribution of methanol masers, is found not to be directly coincident with
the masers and elongated at a much different position angle. IRS-I 3 is found
to be a extended source of mid-infrared emission coming from a cluster of young
dusty sources seen in the near-infrared.Comment: Accepted for publication by the Astrophysical Journal, 27 pages, 9
figure
First Science Results From SOFIA/FORCAST: Super-Resolution Imaging of the S140 Cluster at 37\micron
We present 37\micron\ imaging of the S140 complex of infrared sources
centered on IRS1 made with the FORCAST camera on SOFIA. These observations are
the longest wavelength imaging to resolve clearly the three main sources seen
at shorter wavelengths, IRS 1, 2 and 3, and are nearly at the diffraction limit
of the 2.5-m telescope. We also obtained a small number of images at 11 and
31\micron\ that are useful for flux measurement. Our images cover the area of
several strong sub-mm sources seen in the area -- SMM 1, 2, and 3 -- that are
not coincident with any mid-infrared sources and are not visible in our longer
wavelength imaging either. Our new observations confirm previous estimates of
the relative dust optical depth and source luminosity for the components in
this likely cluster of early B stars. We also investigate the use of
super-resolution to go beyond the basic diffraction limit in imaging on SOFIA
and find that the van Cittert algorithm, together with the "multi-resolution"
technique, provides excellent results
Crystalline Silicate Emission in the Protostellar Binary Serpens--SVS20
We present spatially resolved mid-infrared spectroscopy of the class
I/flat-spectrum protostellar binary system SVS20 in the Serpens cloud core. The
spectra were obtained with the mid-infrared instrument T-ReCS on Gemini-South.
SVS20-South, the more luminous of the two sources, exhibits a mid-infrared
emission spectrum peaking near 11.3 \micron, while SVS20-North exhibits a
shallow amorphous silicate absorption spectrum with a peak optical depth of
. After removal of the the line-of-sight extinction by the
molecular common envelope, the ``protostar-only'' spectra are found to be
dominated by strong amorphous olivine emission peaking near 10 \micron. We also
find evidence for emission from crystalline forsterite and enstatite associated
with both SVS20-S and SVS20-N. The presence of crystalline silicate in such a
young binary system indicates that the grain processing found in more evolved
HAeBe and T Tauri pre-main sequence stars likely begins at a relatively young
evolutionary stage, while mass accretion is still ongoing.Comment: Accepted for publication by The Astrophysical Journa
High Resolution mid-Infrared Imaging of SN 1987A
Using the Thermal-Region Camera and Spectrograph (T-ReCS) attached to the
Gemini South 8m telescope, we have detected and resolved 10 micron emission at
the position of the inner equatorial ring (ER) of supernova SN 1987A at day
6067. ``Hot spots'' similar to those found in the optical and near-IR are
clearly present. The morphology of the 10 micron emission is globally similar
to the morphology at other wavelengths from X-rays to radio. The observed
mid-IR flux in the region of SN1987A is probably dominated by emission from
dust in the ER. We have also detected the ER at 20 micron at a 4 sigma level.
Assuming that thermal dust radiation is the origin of the mid-IR emission, we
derive a dust temperature of 180^{+20}_{-10} K, and a dust mass of 1.- 8.
10^{-5} Mo for the ER. Our observations also show a weak detection of the
central ejecta at 10 micron. We show that previous bolometric flux estimates
(through day 2100) were not significantly contaminated by this newly discovered
emission from the ER. If we assume that the energy input comes from radioactive
decays only, our measurements together with the current theoretical models set
a temperature of 90 leq T leq 100 K and a mass range of 10^{-4} - 2. 10^{-3} Mo
for the dust in the ejecta. With such dust temperatures the estimated thermal
emission is 9(+/-3) 10^{35} erg s^{-1} from the inner ring, and 1.5 (+/-0.5)
10^{36} erg s^{-1} from the ejecta. Finally, using SN 1987A as a template, we
discuss the possible role of supernovae as major sources of dust in the
Universe.Comment: aastex502, 14 pages, 4 figures; Accepted for publication in ApJ
Content changed: new observations, Referee's comments and suggestion
SOFIA/FORCAST and Spitzer/IRAC Imaging of the Ultra Compact H II Region W3(OH) and Associated Protostars in W3
We present infrared observations of the ultra-compact H II region W3(OH) made
by the FORCAST instrument aboard SOFIA and by Spitzer/IRAC. We contribute new
wavelength data to the spectral energy distribution, which constrains the
optical depth, grain size distribution, and temperature gradient of the dusty
shell surrounding the H II region. We model the dust component as a spherical
shell containing an inner cavity with radius ~ 600 AU, irradiated by a central
star of type O9 and temperature ~ 31,000 K. The total luminosity of this system
is 71,000 L_solar. An observed excess of 2.2 - 4.5 microns emission in the SED
can be explained by our viewing a cavity opening or clumpiness in the shell
structure whereby radiation from the warm interior of the shell can escape. We
claim to detect the nearby water maser source W3 (H2O) at 31.4 and 37.1 microns
using beam deconvolution of the FORCAST images. We constrain the flux densities
of this object at 19.7 - 37.1 microns. Additionally, we present in situ
observations of four young stellar and protostellar objects in the SOFIA field,
presumably associated with the W3 molecular cloud. Results from the model SED
fitting tool of Robitaille et al. (2006, 2007} suggest that two objects (2MASS
J02270352+6152357 and 2MASS J02270824+6152281) are intermediate-luminosity (~
236 - 432 L_solar) protostars; one object (2MASS J02270887+6152344) is either a
high-mass protostar with luminosity 3000 L_solar or a less massive young star
with a substantial circumstellar disk but depleted envelope; and one object
(2MASS J02270743+6152281) is an intermediate-luminosity (~ 768 L_solar)
protostar nearing the end of its envelope accretion phase or a young star
surrounded by a circumstellar disk with no appreciable circumstellar envelope.Comment: 12 pages, 8 figures, 2 tables, accepted by Ap
O/IR Polarimetry for the 2010 Decade (GAN): Science at the Edge, Sharp Tools for All
Science opportunities and recommendations concerning optical/infrared
polarimetry for the upcoming decade in the field of Galactic science.
Community-based White Paper to Astro2010 in response to the call for such
papers.Comment: White Paper to the Galactic Neighborhood (GAN) Science Frontiers
Panel of the Astro2010 Decadal Surve
First Science Observations with SOFIA/FORCAST: Properties of Intermediate-Luminosity Protostars and Circumstellar Disks in OMC-2
We examine eight young stellar objects in the OMC-2 star forming region based
on observations from the SOFIA/FORCAST early science phase, the Spitzer Space
Telescope, the Herschel Space Observatory, 2MASS, APEX, and other results in
the literature. We show the spectral energy distributions of these objects from
near-infrared to millimeter wavelengths, and compare the SEDs with those of
sheet collapse models of protostars and circumstellar disks. Four of the
objects can be modelled as protostars with infalling envelopes, two as young
stars surrounded by disks, and the remaining two objects have double-peaked
SEDs. We model the double-peaked sources as binaries containing a young star
with a disk and a protostar. The six most luminous sources are found in a dense
group within a 0.15 x 0.25 pc region; these sources have luminosities ranging
from 300 L_sun to 20 L_sun. The most embedded source (OMC-2 FIR 4) can be fit
by a class 0 protostar model having a luminosity of ~50 L_sun and mass infall
rate of ~10^-4 solar masses per year.Comment: Accepted by ApJ Letter
Understanding Polarized Foreground from Dust: Towards Reliable Measurements of CMB Polarization
Science opportunities and recommendations concerning optical/infrared
polarimetry for the upcoming decade in the field of cosmology. Community-based
White Paper to Astro2010 in response to the call for such papers.Comment: White Paper to the Cosmology and Fundamental Physics (GCT) Science
Frontiers Panel of the Astro2010 Decadal Surve
O/IR Polarimetry for the 2010 Decade (PSF): Science at the Edge, Sharp Tools for All
Science opportunities and recommendations concerning optical/infrared
polarimetry for the upcoming decade in the fields of planetary systems and star
formation. Community-based White Paper to Astro2010 in response to the call for
such papers.Comment: White Paper to the Planetary Systems and Star Formation (PSF) Science
Frontiers Panel of the Astro2010 Decadal Surve