6,422 research outputs found
Metal Abundances of KISS Galaxies. VI. New Metallicity Relations for the KISS Sample of Star-Forming Galaxies
We present updated metallicity relations for the spectral database of
star-forming galaxies (SFGs) found in the KPNO International Spectroscopic
Survey (KISS). New spectral observations of emission-line galaxies (ELGs)
obtained from a variety of telescope facilities provide oxygen abundance
information. A nearly four-fold increase in the number of KISS objects with
robust metallicities relative to our previous analysis provides for an
empirical abundance calibration to compute self-consistent metallicity
estimates for all SFGs in the sample with adequate spectral data. In addition,
a sophisticated spectral energy distribution (SED) fitting routine has provided
robust calculations of stellar mass. With these new and/or improved galaxy
characteristics, we have developed luminosity-metallicity (-) relations,
mass-metallicity (-) relations, and the so-called Fundamental
Metallicity Relation (FMR) for over 1,450 galaxies from the KISS sample. This
KISS - relation is presented for the first time and demonstrates
markedly lower scatter than the KISS - relation. We find that our
relations agree reasonably well with previous publications, modulo modest
offsets due to differences in the SEL metallicity calibrations used. We
illustrate an important bias present in previous - and -
studies involving direct-method () abundances that may result in
systematically lower slopes in these relations. Our KISS FMR shows consistency
with those found in the literature, albeit with a larger scatter. This is
likely a consequence of the KISS sample being biased toward galaxies with high
levels of activity.Comment: Accepted for publication in The Astronomical Journal; 27 pages, 15
figures, 7 tables (with Appendix
Diffuse Atomic and Molecular Gas near IC443
We present an analysis of results on absorption from Ca II, Ca I, K I, and
the molecules CH+, CH, C2, and CN that probes gas interacting with the
supernova remnant IC443. The eleven directions sample material across the
visible nebula and beyond its eastern edge. Most of the neutral material,
including the diatomic molecules, is associated with the ambient cloud detected
via H I and CO emission. Analysis of excitation and chemistry yields gas
densities that are typical of diffuse molecular gas. The low density gas probed
by Ca II extends over a large range in velocities, from -120 to +80 km/s in the
most extreme cases. This gas is distributed among several velocity components,
unlike the situation for the shocked molecular clumps, whose emission occurs
over much the same range but as very broad features. The extent of the
high-velocity absorption suggests a shock velocity of 100 km/s for the
expanding nebula.Comment: To be published in Ap
Tracking the reflexivity of the (dis)engaged citizen: some methodological reflections
The relationship between governments and citizens in many contemporary democracies is haunted by uncertainty and sociologists face the task of listening effectively to citizensâ own reflections on this uncertain relationship. This article reflects on the qualitative methodology of a recently completed UK project which used a combination of diary and multiple interviews/ focus groups to track over a fieldwork period of up to a year citizensâ reflections on their relationship to a public world and the contribution to this of their media consumption. In particular, the article considers how the projectâs multiple methods enabled multiple angles on the inevitable artificiality and performative dimension of the diary process, resulting in rich data on peopleâs complex reflections on the uncertain position of the contemporary citizen
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Getting it right: a model for compliance assessment
Compliance is important for organisations but models and tools to aid understanding of compliance behaviour is limited. This paper argues that the understanding of the interaction between subjects and objects and their intention to comply with requirements of rules and regulations may be a predictor of compliance behaviour. Thus, a Conceptual Compliance Assessment Model (CAM) is developed by extension of Technology Acceptance Model and Activity theory for assessment of compliance behaviour. Data collected and evaluated showed that the awareness and understanding of the mediational tool is critical in realizing the outcome. It also showed that other factors like the perceived usefulness, perceived ease of use, the community and the management set up also affected compliance behaviour. Essentially, the use of CAM will be useful in assessing the compliance activities of subjects which may aid in formulation of behaviour support systems to improve compliance behaviour
Investigating the Cosmic-Ray Ionization Rate Near the Supernova Remnant IC 443 Through H3+ Observations
Observational and theoretical evidence suggests that high-energy Galactic
cosmic rays are primarily accelerated by supernova remnants. If also true for
low-energy cosmic rays, the ionization rate near a supernova remnant should be
higher than in the general Galactic interstellar medium (ISM). We have searched
for H3+ absorption features in 6 sight lines which pass through molecular
material near IC 443---a well-studied case of a supernova remnant interacting
with its surrounding molecular material---for the purpose of inferring the
cosmic-ray ionization rate in the region. In 2 of the sight lines (toward ALS
8828 and HD 254577) we find large H3+ column densities, N(H3+)~3*10^14 cm^-2,
and deduce ionization rates of zeta_2~2*10^-15 s^-1, about 5 times larger than
inferred toward average diffuse molecular cloud sight lines. However, the 3
sigma upper limits found for the other 4 sight lines are consistent with
typical Galactic values. This wide range of ionization rates is likely the
result of particle acceleration and propagation effects, which predict that the
cosmic-ray spectrum and thus ionization rate should vary in and around the
remnant. While we cannot determine if the H3+ absorption arises in post-shock
(interior) or pre-shock (exterior) gas, the large inferred ionization rates
suggest that IC 443 is in fact accelerating a large population of low-energy
cosmic rays. Still, it is unclear whether this population can propagate far
enough into the ISM to account for the ionization rate inferred in diffuse
Galactic sight lines.Comment: 14 pages, 3 figures, 4 table
Asymptotic Giant Branch Stars in the Nearby Dwarf Galaxy Leo P
We have conducted a highly sensitive census of the evolved-star population in the metal-poor dwarf galaxy Leo P and detected four asymptotic giant branch (AGB) star candidates. Leo P is one of the best examples of a nearby analog of high-redshift galaxies because of its primitive metal content (2% of the solar value), proximity, and isolated nature, ensuring a less complicated history. Using medium-band optical photometry from the Hubble Space Telescope (HST), we have classified the AGB candidates by their chemical type. We have identified one oxygen-rich source which appears to be dusty in both the HST and Spitzer observations. Its brightness, however, suggests it may be a planetary nebula or post-AGB object. We have also identified three carbon-rich candidates, one of which may be dusty. Follow-up observations are needed to confirm the nature of these sources and to study the composition of any dust that they produce. If dust is confirmed, these stars would likely be among the most metal-poor examples of dust-producing stars known and will provide valuable insight into our understanding of dust formation at high redshift
New Particles Working Group Report of the Snowmass 2013 Community Summer Study
This report summarizes the work of the Energy Frontier New Physics working
group of the 2013 Community Summer Study (Snowmass)
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