13,423 research outputs found
A Revised Effective Temperature Scale for the Kepler Input Catalog
We present a catalog of revised effective temperatures for stars observed in
long-cadence mode in the Kepler Input Catalog (KIC). We use SDSS griz filters
tied to the fundamental temperature scale. Polynomials for griz
color-temperature relations are presented, along with correction terms for
surface gravity effects, metallicity, and statistical corrections for binary
companions or blending. We compare our temperature scale to the published
infrared flux method (IRFM) scale for VJKs in both open clusters and the Kepler
fields. We find good agreement overall, with some deviations between (J -
Ks)-based temperatures from the IRFM and both SDSS filter and other diagnostic
IRFM color-temperature relationships above 6000 K. For field dwarfs we find a
mean shift towards hotter temperatures relative to the KIC, of order 215 K, in
the regime where the IRFM scale is well-defined (4000 K to 6500 K). This change
is of comparable magnitude in both color systems and in spectroscopy for stars
with Teff below 6000 K. Systematic differences between temperature estimators
appear for hotter stars, and we define corrections to put the SDSS temperatures
on the IRFM scale for them. When the theoretical dependence on gravity is
accounted for we find a similar temperature scale offset between the
fundamental and KIC scales for giants. We demonstrate that statistical
corrections to color-based temperatures from binaries are significant. Typical
errors, mostly from uncertainties in extinction, are of order 100 K.
Implications for other applications of the KIC are discussed.Comment: Corrected for sign flip errors in the gravity corrections. Erratum to
this paper is attached in Appendix. Full version of revised Table 7 can be
found at http://home.ewha.ac.kr/~deokkeun/kic/sdssteff_v2.dat.g
Multiple-antibiotic-resistant bacteria from cockroaches trapped from a public hospital and a nearby students’ hostel in Accra, Ghana
The ability of cockroaches, found in and around hospital settings, to harbour multiple- antibioticresistant bacteria poses serious health implications. This study investigated and compared multiple-antibioticresistant bacteria carried by cockroaches from a hospital environment. Antibiotic susceptibility patterns of isolated pathogenic bacteria on the internal and external surfaces of trapped cockroaches showed that over 60% of the Gram negative enteric bacilli, >90% of the 23 Pseudomonas aeruginosa and all three Gram positive bacteria isolates were resistant to at least four of the antibiotics tested. Necessary control measures need to be taken against the infestation of such facilities by cockroaches.Keywords: Multiple-antibiotic-resistant bacteria, cockroaches, hospital, hostel
Deep crustal heating by neutrinos from the surface of accreting neutron stars
We present a new mechanism for deep crustal heating in accreting neutron
stars. Charged pions () are produced in nuclear collisions on the
neutron star surface during active accretion and upon decay they provide a flux
of neutrinos into the neutron star crust. For massive and/or compact neutron
stars, neutrinos deposit of heat per
accreted nucleon into the inner crust. The strength of neutrino heating is
comparable to the previously known sources of deep crustal heating, such as
from pycnonuclear fusion reactions, and is relevant for studies of cooling
neutron stars. We model the thermal evolution of a transient neutron star in a
low-mass X-ray binary, and in the particular case of the neutron star
MXB~1659-29 we show that additional deep crustal heating requires a higher
thermal conductivity for the neutron star inner crust. A better knowledge of
pion production cross sections near threshold would improve the accuracy of our
predictions.Comment: 12 pages, 9 figures, 3 tables; [Added a new figure and edited the
text in response to Referee's remarks and suggestions
Pion Transparency in 500 MeV C(pi,pi') Reactions?
The question whether there is a pion transparency in 500 MeV scatterings is studied using a semiclassical, hadronic transport
model. The double differential cross sections of this reaction measured at
LAMPF can be largely accounted for, if one uses energy-dependent, anisotropic
angular distributions which are fitted to pion-nucleon scattering data for the
decay of and resonances. The remaining discrepancy
between the data and the calculation sets a limit on effects of more exotic
processes.Comment: Latex file, 11 pages, 3 figures availabe upon request. Phys. Lett. B
in pres
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