4,473 research outputs found
Gust penetration loads and elastic vehicle response for Saturn 5 launch vehicles
Analysis of gust penetration loads and associated elastic vehicle response of Saturn 5 launch vehicles AS-505 through AS-508 penetrating sinusoidal gust
A search for flares and mass ejections on young late-type stars in the open cluster Blanco-1
We present a search for stellar activity (flares and mass ejections) in a
sample of 28 stars in the young open cluster Blanco-1. We use optical spectra
obtained with ESO's VIMOS multi-object spectrograph installed on the VLT. From
the total observing time of 5 hours, we find four H flares but
no distinct indication of coronal mass ejections (CMEs) on the investigated
dK-dM stars. Two flares show "dips" in their light-curves right before their
impulsive phases which are similar to previous discoveries in photometric
light-curves of active dMe stars. We estimate an upper limit of 4 CMEs per
day per star and discuss this result with respect to a semi- empirical
estimation of the CME rate of main-sequence stars. We find that we should have
detected at least one CME per star with a mass of 1-15 g
depending on the star's X-ray luminosity, but the estimated H fluxes
associated with these masses are below the detection limit of our observations.
We conclude that the parameter which mainly influences the detection of stellar
CMEs using the method of Doppler-shifted emission caused by moving plasma is
not the spectral resolution or velocity but the flux or mass of the CME.Comment: Accepted for publication in MNRAS, accepted 2014 June 10, received
2014 June 5, in original form 2014 March 24, 14 pages, 5 figure
- A tool for multiband light curve modeling of planetary transits and stellar spots
Several studies have shown that stellar activity features, such as occulted
and non-occulted starspots, can affect the measurement of transit parameters
biasing studies of transit timing variations and transmission spectra. We
present , which we designed to model multiband transit
light curves showing starspot anomalies, inferring both transit and spot
parameters. The code follows a pixellation approach to model the star with its
corresponding limb darkening, spots, and transiting planet on a two dimensional
Cartesian coordinate grid. We combine with an MCMC
framework to study and derive exoplanet transmission spectra, which provides
statistically robust values for the physical properties and uncertainties of a
transiting star-planet system. We validate 's performance
by analyzing eleven synthetic light curves of four different star-planet
systems and 20 transit light curves of the well-studied WASP-41b system. We
also investigate the impact of starspots on transit parameters and derive
wavelength dependent transit depth values for WASP-41b covering a range of
6200-9200 , indicating a flat transmission spectrum.Comment: 17 pages, 22 figures; accepted for publication in Astronomy &
Astrophysic
Effects of shock-induced separation Technical summary report
Supersonic and subsonic shock wave boundary layer separation studies on aeroelasticity of Saturn launch vehicle
YREC: The Yale Rotating Stellar Evolution Code
The stellar evolution code YREC is outlined with emphasis on its applications
to helio- and asteroseismology. The procedure for calculating calibrated solar
and stellar models is described. Other features of the code such as a non-local
treatment of convective core overshoot, and the implementation of a
parametrized description of turbulence in stellar models, are considered in
some detail. The code has been extensively used for other astrophysical
applications, some of which are briefly mentioned at the end of the paper.Comment: 10 pages, 2 figures, ApSS accepte
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