393 research outputs found
High resolution near-infrared imaging of submillimeter galaxies
We present F110W (~J) and F160W (~H) observations of ten submillimeter
galaxies (SMGs) obtained with the Hubble Space Telescope's (HST's) NICMOS
camera. Our targets have optical redshifts in the range 2.20<z<2.81 confirmed
by millimeter CO or mid-IR spectroscopy, guaranteeing that the two bands sample
the rest-frame optical with the Balmer break falling between them. Eight of ten
are detected in both bands, while two are detected in F160W only. We study
their F160W morphologies, applying a maximum-deblending detection algorithm to
distinguish multiple- from single-component configurations, leading to
reassessments for several objects. Based on our NICMOS imaging and/or previous
dynamical evidence we identify five SMGs as multiple sources, which we
interpret as merging systems. Additionally, we calculate morphological
parameters asymmetry (A) and Gini coefficient (G); thanks to our sample's
limited redshift range we recover the trend that multiple-component,
merger-like morphologies are reflected in higher asymmetries. We analyze the
stellar populations of nine objects with F110W/F160W photometry, using archival
HST optical data when available. For multiple systems, we are able to model the
individual components that build up an SMG. With the available data we cannot
discriminate among star formation histories, but we constrain stellar masses
and mass ratios for merger-like SMG systems, obtaining a mean
log(M_*/M_sun)=10.9+/-0.2 for our full sample, with individual values
log(M_*/M_sun)~9.6-11.8. The morphologies and mass ratios of the least and most
massive systems match the predictions of the major-merger and cold accretion
SMG formation scenarios, respectively, suggesting that both channels may have a
role in the population's origin.Comment: 41 pages preprint, 3 figures, published in ApJ on 2013 May 1
K2-97b: A (Re-?)Inflated Planet Orbiting a Red Giant Star
Strongly irradiated giant planets are observed to have radii larger than thermal evolution models predict. Although these inflated planets have been known for over 15 years, it is unclear whether their inflation is caused by the deposition of energy from the host star or the inhibited cooling of the planet. These processes can be distinguished if the planet becomes highly irradiated only when the host star evolves onto the red giant branch. We report the discovery of K2-97b, a 1.31 ± 0.11 R_J, 1.10 ± 0.11 M_J planet orbiting a 4.20 ± 0.14 R⊙, 1.16 ± 0.12 M⊙ red giant star with an orbital period of 8.4 days. We precisely constrained stellar and planetary parameters by combining asteroseismology, spectroscopy, and granulation noise modeling along with transit and radial velocity measurements. The uncertainty in planet radius is dominated by systematic differences in transit depth, which we measure to be up to 30% between different light-curve reduction methods. Our calculations indicate the incident flux on this planet was 170^(+140)_(-60) times the incident flux on Earth, while the star was on the main sequence. Previous studies suggest that this incident flux is insufficient to delay planetary cooling enough to explain the present planet radius. This system thus provides the first evidence that planets may be inflated directly by incident stellar radiation rather than by delayed loss of heat from formation. Further studies of planets around red giant branch stars will confirm or contradict this hypothesis and may reveal a new class of re-inflated planets
The Atacama Cosmology Telescope: The LABOCA/ACT Survey of Clusters at All Redshifts
We present a multi-wavelength analysis of eleven Sunyaev Zel'dovich effect
(SZE)-selected galaxy clusters (ten with new data) from the Atacama Cosmology
Telescope (ACT) southern survey. We have obtained new imaging from the Large
APEX Bolometer Camera (345GHz; LABOCA) on the Atacama Pathfinder EXperiment
(APEX) telescope, the Australia Telescope Compact Array (2.1GHz; ATCA), and the
Spectral and Photometric Imaging Receiver (250, 350, and ;
SPIRE) on the Herschel Space Observatory. Spatially-resolved 345GHz SZE
increments with integrated S/N > 5 are found in six clusters. We compute 2.1GHz
number counts as a function of cluster-centric radius and find significant
enhancements in the counts of bright sources at projected radii . By extrapolating in frequency, we predict that the combined
signals from 2.1GHz-selected radio sources and 345GHz-selected SMGs contaminate
the 148GHz SZE decrement signal by ~5% and the 345GHz SZE increment by ~18%.
After removing radio source and SMG emission from the SZE signals, we use ACT,
LABOCA, and (in some cases) new Herschel SPIRE imaging to place constraints on
the clusters' peculiar velocities. The sample's average peculiar velocity
relative to the cosmic microwave background is .Comment: 19 pages, 11 figures, Accepted for Publication in The Astrophysical
Journa
Herschel and ALMA observations of the ISM in massive high-redshift galaxy clusters
The Sunyaev-Zel'dovich effect (SZE) can be used to select samples of galaxy clusters that are essentially mass-limited out to arbitrarily high redshifts. I will present results from an investigation of the star formation properties of galaxies in four massive clusters, extending to z~1, which were selected on the basis of their SZE decrements in the Atacama Cosmology Telescope (ACT) survey. All four clusters have been imaged with Herschel/PACS (tracing star formation rate) and two with ALMA (tracing dust and cold gas mass); newly discovered ALMA CO(4-3) and [CI] line detections expand an already large sample of spectroscopically confirmed cluster members. Star formation rate appears to anti-correlate with environmental density, but this trend vanishes after controlling for stellar mass. Elevated star formation and higher CO excitation are seen in "El Gordo," a violent cluster merger, relative to a virialized cluster at a similar high (z~1) redshift. Also exploiting ATCA 2.1 GHz observations to identify radio-loud active galactic nuclei (AGN) in our sample, I will use these data to develop a coherent picture of how environment influences galaxies' ISM properties and evolution in the most massive clusters at early cosmic times
Revised Stellar Properties of Kepler Targets for the Quarter 1-16 Transit Detection Run
We present revised properties for 196,468 stars observed by the NASA Kepler
Mission and used in the analysis of Quarter 1-16 (Q1-Q16) data to detect and
characterize transiting exoplanets. The catalog is based on a compilation of
literature values for atmospheric properties (temperature, surface gravity, and
metallicity) derived from different observational techniques (photometry,
spectroscopy, asteroseismology, and exoplanet transits), which were then
homogeneously fitted to a grid of Dartmouth stellar isochrones. We use
broadband photometry and asteroseismology to characterize 11,532 Kepler targets
which were previously unclassified in the Kepler Input Catalog (KIC). We report
the detection of oscillations in 2,762 of these targets, classifying them as
giant stars and increasing the number of known oscillating giant stars observed
by Kepler by ~20% to a total of ~15,500 stars. Typical uncertainties in derived
radii and masses are ~40% and ~20%, respectively, for stars with photometric
constraints only, and 5-15% and ~10% for stars based on spectroscopy and/or
asteroseismology, although these uncertainties vary strongly with spectral type
and luminosity class. A comparison with the Q1-Q12 catalog shows a systematic
decrease in radii for M dwarfs, while radii for K dwarfs decrease or increase
depending on the Q1-Q12 provenance (KIC or Yonsei-Yale isochrones). Radii of
F-G dwarfs are on average unchanged, with the exception of newly identified
giants. The Q1-Q16 star properties catalog is a first step towards an improved
characterization of all Kepler targets to support planet occurrence studies.Comment: 20 pages, 14 figures, 5 tables; accepted for publication in ApJS;
electronic versions of Tables 4 and 5 are available as ancillary files (see
sidebar on the right), and an interactive version of Table 5 is available at
the NASA Exoplanet Archive (http://exoplanetarchive.ipac.caltech.edu/
The impact of a visual arts program on quality of life, communication, and well-being of people living with dementia: a mixed-methods longitudinal investigation
Background: Research reviews highlight methodological limitations and gaps in the evidence base for the arts in dementia care. In response, we developed a 12-week visual art program and evaluated the impact on people living with dementia through a mixed-methods longitudinal investigation.
Methods: One hundred and twenty-five people living with mild to severe dementia were recruited across three research settings in England and Wales (residential care homes, a county hospital, and community venues). Quantitative and qualitative data on quality of life (QoL), communication and perceptions of the program were obtained through interviews and self-reports with participants and their carers. Eight domains of well-being were measured using a standardized observation tool, and data compared to an alternative activity with no art.
Results: Across all sites, scores for the well-being domains of interest, attention, pleasure, self-esteem, negative affect, and sadness were significantly better in the art program than the alternative condition. Proxy-reported QoL significantly improved between baseline and 3-month follow-up, but no improvements in QoL were reported by the participants with dementia. This was contrasted by their qualitative accounts, which described a stimulating experience important for social connectedness, well-being, and inner-strength. Communication deteriorated between baseline and follow-up in the hospital setting, but improved in the residential care setting.
Conclusions: The findings highlight the potential for creative aging within dementia care, the benefits of art activities and the influence of the environment. We encourage dementia care providers and arts and cultural services to work toward embedding art activities within routine care provision
The effect of review writing on learning engagement in channel partner relationship management
To develop the knowledge and skill sets of channel partner firms, firms increasingly introduce learning programs as part of their relationship management strategies. Yet, the engagement of channel partners in these programs tends to be low though. The current research, conducted in collaboration with a Fortune 100 information technology company, examines ways to strengthen learning engagement. In accordance with self-regulated learning theory, the authors propose and demonstrate that when channel partners write reviews of a learning module that they attended, beyond providing ratings,they are better able to reflect on the relevance of their learning experience and they are further engaged in learning activities. The audience and focus of these written reviews determine the engagement of the channel partner sales personnel. Therefore, review writing is a valuable, informal mechanism to motivate them. These effects are moderated by characteristics of both the channel partner (learning orientation of the salesperson, identification with the manufacturer) and the relationship with the manufacturer (length and exclusivity)
Fundamental Properties of Kepler Planet-Candidate Host Stars using Asteroseismology
We have used asteroseismology to determine fundamental properties for 66
Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in
radius and mass, respectively. The results include new asteroseismic solutions
for four host stars with confirmed planets (Kepler-4, Kepler-14, Kepler-23 and
Kepler-25) and increase the total number of Kepler host stars with
asteroseismic solutions to 77. A comparison with stellar properties in the
planet-candidate catalog by Batalha et al. shows that radii for subgiants and
giants obtained from spectroscopic follow-up are systematically too low by up
to a factor of 1.5, while the properties for unevolved stars are in good
agreement. We furthermore apply asteroseismology to confirm that a large
majority of cool main-sequence hosts are indeed dwarfs and not misclassified
giants. Using the revised stellar properties, we recalculate the radii for 107
planet candidates in our sample, and comment on candidates for which the radii
change from a previously giant-planet/brown-dwarf/stellar regime to a
sub-Jupiter size, or vice versa. A comparison of stellar densities from
asteroseismology with densities derived from transit models in Batalha et al.
assuming circular orbits shows significant disagreement for more than half of
the sample due to systematics in the modeled impact parameters, or due to
planet candidates which may be in eccentric orbits. Finally, we investigate
tentative correlations between host-star masses and planet candidate radii,
orbital periods, and multiplicity, but caution that these results may be
influenced by the small sample size and detection biases.Comment: 19 pages, 10 figures, 4 tables; accepted for publication in ApJ;
machine-readable versions of tables 1-3 are available as ancillary files or
in the source code; v2: minor changes to match published versio
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