596 research outputs found
The Spitzer c2d survey of large, nearby, interstellar clouds. IV. Lupus observed with mips
We present maps of 7.78 deg(2) of the Lupus molecular cloud complex at 24, 70, and 160 μm. They were made with the Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) instrument as part of the Spitzer Legacy Program "From Molecular Cores to Planet-Forming Disks" (c2d). The maps cover three separate regions in Lupus, denoted I, III, and IV. We discuss the c2d pipeline and how our data processing differs from it. We compare source counts in the three regions with two other data sets and predicted star counts from the Wainscoat model. This comparison shows the contribution from background galaxies in Lupus I. We also create two color-magnitude diagrams using the 2MASS and MIPS data. From these results, we can identify background galaxies and distinguish them from probable young stellar objects. The sources in our catalogs are classified based on their spectral energy distribution ( SED) from 2MASS and Spitzer wavelengths to create a sample of young stellar object candidates. From 2MASS data, we create extinction maps for each region and note a strong correspondence between the extinction and the 160 μm emission. The masses we derived in each Lupus cloud from our extinction maps are compared to masses estimated from (CO)-C-13 and C-18 O and found to be similar to our extinction masses in some regions, but significantly different in others. Finally, based on our color-magnitude diagrams, we selected 12 of our reddest candidate young stellar objects for individual discussion. Five of the 12 appear to be newly discovered YSOs
The Mid-Infrared Extinction Law in the Ophiuchus, Perseus, and Serpens Molecular Clouds
We compute the mid-infrared extinction law from 3.6-24 microns in three
molecular clouds: Ophiuchus, Perseus, and Serpens, by combining data from the
"Cores to Disks" Spitzer Legacy Science program with deep JHKs imaging. Using a
new technique, we are able to calculate the line-of-sight extinction law
towards each background star in our fields. With these line-of-sight
measurements, we create, for the first time, maps of the chi-squared deviation
of the data from two extinction law models. Because our chi-squared maps have
the same spatial resolution as our extinction maps, we can directly observe the
changing extinction law as a function of the total column density. In the
Spitzer IRAC bands, 3.6-8 microns, we see evidence for grain growth. Below
, our extinction law is well-fit by the Weingartner & Draine
(2001) diffuse interstellar medium dust model. As the extinction
increases, our law gradually flattens, and for , the data are
more consistent with the Weingartner & Draine model that uses
larger maximum dust grain sizes. At 24 microns, our extinction law is 2-4 times
higher than the values predicted by theoretical dust models, but is more
consistent with the observational results of Flaherty et al. (2007). Lastly,
from our chi-squared maps we identify a region in Perseus where the IRAC
extinction law is anomalously high considering its column density. A steeper
near-infrared extinction law than the one we have assumed may partially explain
the IRAC extinction law in this region.Comment: 38 pages, 19 figures in pre-print format. Accepted for publication in
ApJ. A version with full-resolution figures can be found here:
http://peggysue.as.utexas.edu/SIRTF
The Submillimeter Polarization Spectrum of M17
We present 450 {\mu}m polarimetric observations of the M17 molecular cloud
obtained with the SHARP polarimeter at the Caltech Submillimeter Observatory.
Across the observed region, the magnetic field orientation is consistent with
previous submillimeter and far-infrared polarization measurements. Our
observations are centered on a region of the molecular cloud that has been
compressed by stellar winds from a cluster of OB stars. We have compared these
new data with previous 350 {\mu}m polarimetry and find an anti-correlation
between the 450 to 350 {\mu}m polarization magnitude ratio and the ratio of 21
cm to 450 {\mu}m intensity. The polarization ratio is lower near the east end
of the studied region where the cloud is exposed to stellar winds and
radiation. At the west end of the region, the polarization ratio is higher. We
interpret the varying polarization spectrum as evidence supporting the
radiative alignment torque (RAT) model for grain alignment, implying higher
alignment efficiency in the region that is exposed to a higher anisotropic
radiation field.Comment: 24 pages, 10 figure
Diagnosis, Investigation and Management of Patients with Acute and Chronic Myocardial Injury
The application of high-sensitivity cardiac troponins in clinical practice has led to an increase in the recognition of elevated concentrations in patients without myocardial ischaemia. The Fourth Universal Definition of Myocardial Infarction encourages clinicians to classify such patients as having an acute or chronic myocardial injury based on the presence or absence of a rise or a fall in cardiac troponin concentrations. Both conditions may be caused by a variety of cardiac and non-cardiac conditions, and evidence suggests that clinical outcomes are worse than patients with myocardial infarction due to atherosclerotic plaque rupture, with as few as one-third of patients alive at 5 years. Major adverse cardiovascular events are comparable between populations, and up to three-fold higher than healthy individuals. Despite this, no evidence-based strategies exist to guide clinicians in the investigation of non-ischaemic myocardial injury. This review explores the aetiology of myocardial injury and proposes a simple framework to guide clinicians in early assessment to identify those who may benefit from further investigation and treatment for those with cardiovascular disease
The Spitzer Survey of Interstellar Clouds in the Gould Belt. VI. The Auriga-California Molecular Cloud observed with IRAC and MIPS
We present observations of the Auriga-California Molecular Cloud (AMC) at
3.6, 4.5, 5.8, 8.0, 24, 70 and 160 micron observed with the IRAC and MIPS
detectors as part of the Spitzer Gould Belt Legacy Survey. The total mapped
areas are 2.5 sq-deg with IRAC and 10.47 sq-deg with MIPS. This giant molecular
cloud is one of two in the nearby Gould Belt of star-forming regions, the other
being the Orion A Molecular Cloud (OMC). We compare source counts, colors and
magnitudes in our observed region to a subset of the SWIRE data that was
processed through our pipeline. Using color-magnitude and color-color diagrams,
we find evidence for a substantial population of 166 young stellar objects
(YSOs) in the cloud, many of which were previously unknown. Most of this
population is concentrated around the LkHalpha 101 cluster and the filament
extending from it. We present a quantitative description of the degree of
clustering and discuss the fraction of YSOs in the region with disks relative
to an estimate of the diskless YSO population. Although the AMC is similar in
mass, size and distance to the OMC, it is forming about 15 - 20 times fewer
stars.Comment: (30 pages, 17 figures (2 multipage figures), accepted for publication
in ApJ
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