6,649 research outputs found
HATS-1b: The First Transiting Planet Discovered by the HATSouth Survey
We report the discovery of HATS-1b, a transiting extrasolar planet orbiting
the moderately bright V=12.05 G dwarf star GSC 6652-00186, and the first planet
discovered by HATSouth, a global network of autonomous wide-field telescopes.
HATS-1b has a period P~3.4465 d, mass Mp~1.86MJ, and radius Rp~1.30RJ. The host
star has a mass of 0.99Msun, and radius of 1.04Rsun. The discovery light curve
of HATS-1b has near continuous coverage over several multi-day periods,
demonstrating the power of using a global network of telescopes to discover
transiting planets.Comment: Submitted to AJ 10 pages, 5 figures, 6 table
Against academic identity
‘Academic identity’ is a key issue for debates about the professionalisation of university teaching and research, as well as the meaning and purpose of higher education. However, the concept of ‘academic identity’ is not adequate to the critical task for which it is utilised as it fails to deal with the real nature of work in capitalist society. It is important to move on from the mystifying and reified politics of identity and seek to understand academic life so that its alienated forms can be transformed. This can be done by grasping the essential aspects of capitalist work in both its abstract and concrete forms, as well as the historical and social processes out of which academic labour has emerged
PRS3 The Effect Of Aat Replacement Therapy on Patient Length And Quality Of Life - a Markov Model
Quantum graphs where back-scattering is prohibited
We describe a new class of scattering matrices for quantum graphs in which
back-scattering is prohibited. We discuss some properties of quantum graphs
with these scattering matrices and explain the advantages and interest in their
study. We also provide two methods to build the vertex scattering matrices
needed for their construction.Comment: 15 page
Anomalous phonon behavior in the high temperature shape memory alloy: TiPd:Cr
Ti50 Pd50-xCrx is a high temperature shape memory alloy with a martensitic
transformation temperature strongly dependent on the Cr composition. Prior to
the transformation a premartensitic phase is present with an incommensurate
modulated cubic lattice with wave vector of q0=(0.22, 0.22, 0). The temperature
dependence of the diffuse scattering in the cubic phase is measured as a
function temperature for x=6.5, 8.5, and 10 at. %. The lattice dynamics has
been studied and reveals anomalous temperature and q-dependence of the
[110]-TA2 transverse phonon branch. The phonon linewidth is broad over the
entire Brillouin zone and increases with decreasing temperature, contrary to
the behavior expected for anharmonicity. No anomaly is observed at q0. The
results are compared with first principles calculation of the phonon structure.Comment: 26 pages, 11 figure
Discovery and Characterization of Transiting SuperEarths Using an All-Sky Transit Survey and Follow-up by the James Webb Space Telescope
Doppler and transit surveys are finding extrasolar planets of ever smaller
mass and radius, and are now sampling the domain of superEarths (1-3 Earth
radii). Recent results from the Doppler surveys suggest that discovery of a
transiting superEarth in the habitable zone of a lower main sequence star may
be possible. We evaluate the prospects for an all-sky transit survey targeted
to the brightest stars, that would find the most favorable cases for
photometric and spectroscopic characterization using the James Webb Space
Telescope (JWST). We use the proposed Transiting Exoplanet Survey Satellite
(TESS) as representative of an all-sky survey. We couple the simulated TESS
yield to a sensitivity model for the MIRI and NIRSpec instruments on JWST. We
focus on the TESS planets with radii between Earth and Neptune. Our simulations
consider secondary eclipse filter photometry using JWST/MIRI, comparing the 11-
and 15-micron bands to measure CO2 absorption in superEarths, as well as
JWST/NIRSpec spectroscopy of water absorption from 1.7-3.0 microns, and CO2
absorption at 4.3-microns. We project that TESS will discover about eight
nearby habitable transiting superEarths. The principal sources of uncertainty
in the prospects for JWST characterization of habitable superEarths are
superEarth frequency and the nature of superEarth atmospheres. Based on our
estimates of these uncertainties, we project that JWST will be able to measure
the temperature, and identify molecular absorptions (water, CO2) in one to four
nearby habitable TESS superEarths.Comment: accepted for PASP; added discussion and figure for habitable planets;
abridged Abstrac
Observation of the full 12-hour-long transit of the exoplanet HD80606b. Warm-Spitzer photometry and SOPHIE spectroscopy
We present new observations of a transit of the 111-day-period exoplanet
HD80606b. Using the Spitzer Space Telescope and its IRAC camera on the
post-cryogenic mission, we performed a 19-hour-long photometric observation of
HD80606 that covers the full transit of 13-14 January 2010. We complement this
photometric data by new spectroscopic observations that we simultaneously
performed with SOPHIE at Haute-Provence Observatory. This provides radial
velocity measurements of the first half of the transit that was previously
uncovered with spectroscopy. This new data set allows the parameters of this
singular planetary system to be significantly refined. We obtained a
planet-to-star radius ratio R_p/R_* = 0.1001 +/- 0.0006 that is slightly lower
than the one measured from previous ground observations. We detected a feature
in the Spitzer light curve that could be due to a stellar spot. We also found a
transit timing about 20 minutes earlier than the ephemeris prediction; this
could be caused by actual TTVs due to an additional body in the system or by
underestimated systematic uncertainties. The sky-projected angle between the
spin-axis of HD80606 and the normal to the planetary orbital plane is found to
be lambda = 42 +/- 8 degrees thanks to the fit of the Rossiter-McLaughlin
anomaly. This allows scenarios with aligned spin-orbit to be definitively
rejected. Over the twenty planetary systems with measured spin-orbit angles, a
few of them are misaligned; this is probably the signature of two different
evolution scenarios for misaligned and aligned systems, depending if they
experienced or not gravitational interaction with a third body. As in the case
of HD80606b, most of the planetary systems including a massive planet are
tilted; this could be the signature of a separate evolution scenario for
massive planets in comparison with Jupiter-mass planets.Comment: 14 pages, 9 figures, 2 tables, accepted for publication in A&
Poles and zeros of the scattering matrix associated to defect modes
We analyze electromagnetic waves propagation in one-dimensional periodic
media with single or periodic defects. The study is made both from the point of
view of the modes and of the diffraction problem. We provide an explicit
dispersion equation for the numerical calculation of the modes, and we
establish a connection between modes and poles and zeros of the scattering
matrix.Comment: 6 pages (Revtex), no figure
Dielectric multilayer waveguides for TE and TM mode matching
We analyse theoretically for the first time to our knowledge the perfect
phase matching of guided TE and TM modes with a multilayer waveguide composed
of linear isotropic dielectric materials. Alongside strict investigation into
dispersion relations for multilayer systems, we give an explicit qualitative
explanation for the phenomenon of mode matching on the basis of the standard
one-dimensional homogenization technique, and discuss the minimum number of
layers and the refractive index profile for the proposed device scheme. Direct
applications of the scheme include polarization-insensitive, intermodal
dispersion-free planar propagation, efficient fibre-to-planar waveguide
coupling and, potentially, mode filtering. As a self-sufficient result, we
present compact analytical expressions for the mode dispersion in a finite,
N-period, three-layer dielectric superlattice.Comment: 13 pages with figure
- …