5,879 research outputs found
A new eclipsing binary system with a pulsating component detected by CoRoT
We report the discovery of CoRoT 102980178 (R.A.= 06:50:12.10, Dec.=
-02:41:21.8, J2000) an Algol-type eclipsing binary system with a pulsating
component (oEA). It was identified using a publicly available 55 day long
monochromatic lightcurve from the CoRoT initial run dataset (exoplanet field).
Eleven consecutive 1.26m deep total primary and the equal number of 0.25m deep
secondary eclipses (at phase 0.50) were observed. The following light elements
for the primary eclipse were derived: HJD_MinI= 2454139.0680 + 5.0548d x E. The
lightcurve modeling leads to a semidetached configuration with the photometric
mass ratio q=0.2 and orbital inclination i=85 deg. The out-of-eclipse
lightcurve shows ellipsoidal variability and positive O'Connell effect as well
as clear 0.01m pulsations with the dominating frequency of 2.75 c/d. The
pulsations disappear during the primary eclipses, which indicates the primary
(more massive) component to be the pulsating star. Careful frequency analysis
reveals the second independent pulsation frequency of 0.21 c/d and numerous
combinations of these frequencies with the binary orbital frequency and its
harmonics. On the basis of the CoRoT lightcurve and ground based multicolor
photometry, we favor classification of the pulsating component as a gamma
Doradus type variable, however, classification as an SPB star cannot be
excluded.Comment: 16 pages, 7 figures, 3 tables, accepted to Communications in
Asteroseismolog
Security Attributes Based Digital Rights Management
Most real-life systems delegate responsibilities to different authorities. We apply this model to a digital rights management system, to achieve flexible security. In our model a hierarchy of authorities issues certificates that are linked by cryptographic means. This linkage establishes a chain of control, identity-attribute-rights, and allows flexible rights control over content. Typical security objectives, such as identification, authentication, authorization and access control can be realised. Content keys are personalised to detect illegal super distribution. We describe a working prototype, which we develop using standard techniques, such as standard certificates, XML and Java. We present experimental results to evaluate the scalability of the system. A formal analysis demonstrates that our design is able to detect a form of illegal super distribution
Recommended from our members
Big Data Assurance Evaluation: An SLA-Based Approach.
The Big Data community has started noticing that there is the need to complete Big Data platforms with assurance techniques proving the correct behavior of Big Data
analytics and management. In this paper, we propose a Big Data assurance solution based on Service-Level Agreements (SLAs), focusing on a platform providing Model-based Big Data Analytics-as-a-Service (MBDAaaS)
SOPHIE velocimetry of Kepler transit candidates VI. An additional companion in the KOI-13 system
We report the discovery of a new stellar companion in the KOI-13 system.
KOI-13 is composed by two fast-rotating A-type stars of similar magnitude. One
of these two stars hosts a transiting planet discovered by Kepler. We obtained
new radial velocity measurements using the SOPHIE spectrograph at the
Observatoire de Haute-Provence that revealed an additional companion in this
system. This companion has a mass between 0.4 and 1 Msun and orbits one of the
two main stars with a period of 65.831 \pm 0.029 days and an eccentricity of
0.52 \pm 0.02. The radial velocities of the two stars were derived using a
model of two fast-rotating line profiles. From the residuals, we found a hint
of the stellar variations seen in the Kepler light curve with an amplitude of
about 1.41 km/s and a period close to the rotational period. This signal
appears to be about three order of magnitude larger than expected for stellar
activity. From the analysis of the residuals, we also put a 3-sigma upper-limit
on the mass of the transiting planet KOI-13.01 of 14.8 Mjup and 9.4 Mjup,
depending on which star hosts the transit. We found that this new companion has
no significant impact on the photometric determination of the mass of KOI-13.01
but is expected to affect precise infrared photometry. Finally, using dynamical
simulations, we infer that the new companion is orbiting around KOI-13B while
the transiting planet candidate is expected to orbit KOI-13A. Thus, the
transiting planet candidate KOI-13.01 is orbiting the main component of a
hierarchical triple system.Comment: Accepted in A&A Letters. 4 pages including 4 figures and the RV tabl
Status of ITER neutral beam cell remote handling system
The ITER neutral beam cell will contain up to three heating neutral beams and
one diagnostic neutral beam, and four upper ports. Though manual maintenance
work is envisaged within the cell, when containment is breached, or the
radiological protection is removed the maintenance must be conducted remotely.
This maintenance constitutes the removal and replacement of line replaceable
units, and their transport to and from a cask docked to the cell. A design of
the remote handling system has been prepared to concept level which this paper
describes including the development of a beam line transporter, beam source
remote handling equipment, upper port remote handling equipment and equipment
for the maintenance of the neutral shield. This equipment has been developed
complete the planned maintenance tasks for the components of the neutral beam
cell and to have inherent flexibility to enable as yet unforeseen tasks and
recovery operations to be performed.Comment: 4 pages, 9 figure
SOPHIE velocimetry of Kepler transit candidates XI. Kepler-412 system: probing the properties of a new inflated hot Jupiter
We confirm the planetary nature of Kepler-412b, listed as planet candidate
KOI-202 in the Kepler catalog, thanks to our radial velocity follow-up program
of Kepler-released planet candidates, which is on going with the SOPHIE
spectrograph. We performed a complete analysis of the system by combining the
Kepler observations from Q1 to Q15, to ground-based spectroscopic observations
that allowed us to derive radial velocity measurements, together with the host
star parameters and properties. We also analyzed the light curve to derive the
star's rotation period and the phase function of the planet, including the
secondary eclipse. We found the planet has a mass of 0.939 0.085
M and a radius of 1.325 0.043 R which makes it a member
of the bloated giant subgroup. It orbits its G3 V host star in 1.72 days. The
system has an isochronal age of 5.1 Gyr, consistent with its moderate stellar
activity as observed in the Kepler light curve and the rotation of the star of
17.2 1.6 days. From the detected secondary, we derived the day side
temperature as a function of the geometric albedo and estimated the geometrical
albedo, Ag, is in the range 0.094 to 0.013. The measured night side flux
corresponds to a night side brightness temperature of 2154 83 K, much
greater than what is expected for a planet with homogeneous heat
redistribution. From the comparison to star and planet evolution models, we
found that dissipation should operate in the deep interior of the planet. This
modeling also shows that despite its inflated radius, the planet presents a
noticeable amount of heavy elements, which accounts for a mass fraction of 0.11
0.04.Comment: 11 pages, 9 figure
SOPHIE velocimetry of Kepler transit candidates XIV. A joint photometric, spectroscopic, and dynamical analysis of the Kepler-117 system
As part of our follow-up campaign of Kepler planets, we observed Kepler-117
with the SOPHIE spectrograph at the Observatoire de Haute-Provence. This
F8-type star hosts two transiting planets in non-resonant orbits. The planets,
Kepler-117 b and c, have orbital periods and days,
and show transit-timing variations (TTVs) of several minutes. We performed a
combined Markov chain Monte Carlo (MCMC) fit on transits, radial velocities,
and stellar parameters to constrain the characteristics of the system. We
included the fit of the TTVs in the MCMC by modeling them with dynamical
simulations. In this way, consistent posterior distributions were drawn for the
system parameters. According to our analysis, planets b and c have notably
different masses ( and M) and low
orbital eccentricities ( and ). The
uncertainties on the derived parameters are strongly reduced if the fit of the
TTVs is included in the combined MCMC. The TTVs allow measuring the mass of
planet b, although its radial velocity amplitude is poorly constrained.
Finally, we checked that the best solution is dynamically stable.Comment: 16 pages, of whom 5 of online material.12 figures, of whom 2 in the
online material. 7 tables, of whom 4 in the online material. Published in A&
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