697 research outputs found
MOST Space Telescope Photometry of the 2010 January Transit of Extrasolar Planet HD80606b
We present observations of the full January 2010 transit of HD80606b from the
Canadian microsatellite, Microvariability and Oscillations of Stars (MOST). By
employing a space-based telescope, we monitor the entire transit thus limiting
systematic errors that result from ground observations. We determine
measurements for the planetary radius (R_{p}=0.987\pm0.061R_{Jup}) and
inclination (i=89.283^{o}\pm0.024) by constraining our fits with the observed
parameters of different groups. Our measured mid-transit time of
2455210.6449\pm0.0034 HJD is consistant with the 2010 Spitzer results and is 20
minutes earlier than predicted by groups who observed the June 2009 transit.Comment: 3 figure
Kepler Uniform Modeling of KOIs: MCMC Notes for Data Release 25
This document describes data products related to the reported planetary parameters and uncertainties for the Kepler Objects of Interest (KOIs) based on a Markov-Chain-Monte-Carlo (MCMC) analysis. Reported parameters, uncertainties and data products can be found at the NASA Exoplanet Archive . The codes used for this data analysis are available on the Github website (Rowe 2016). The relevant paper for details of the calculations is Rowe et al. (2015). The main differences between the model fits discussed here and those in the DR24 catalogue are that the DR25 light curves were used in the analysis, our processing of the MAST light curves took into account different data flags, the number of chains calculated was doubled to 200 000, and the parameters which are reported are based on a damped least-squares fit, instead of the median value from the Markov chain or the chain with the lowest 2 as reported in the past
High fidelity simulations of ion trajectories in miniature ion traps using the boundary-element method
In this paper we present numerical modeling results for endcap and linear ion
traps, used for experiments at the National Physical Laboratory in the UK and
Innsbruck University respectively. The secular frequencies for Strontium-88 and
Calcium-40 ions were calculated from ion trajectories, simulated using
boundary-element and finite-difference numerical methods. The results were
compared against experimental measurements. Both numerical methods showed high
accuracy with boundary-element method being more accurate. Such simulations can
be useful tools for designing new traps and trap arrays. They can also be used
for obtaining precise trapping parameters for desired ion control when no
analytical approach is possible as well as for investigating the ion heating
rates due to thermal electronic noise.Comment: 6 pages, 5 figures, changes made to the text according to the
editor's and referee's comment
A stable quasi-periodic 4.18 d oscillation and mysterious occultations in the 2011 MOST light curve of TWHya
We present an analysis of the 2011 photometric observations of TW Hya by the
MOST satellite; this is the fourth continuous series of this type. The
large-scale light variations are dominated by a strong, quasi-periodic 4.18 d
oscillation with superimposed, apparently chaotic flaring activity; the former
is most likely produced by stellar rotation with one large hot spot created by
a stable accretion funnel in the stable regime of accretion while the latter
may be produced by small hot spots, created at moderate latitudes by unstable
accretion tongues. A new, previously unnoticed feature is a series of
semi-periodic, well defined brightness dips of unknown nature of which 19 were
observed during 43 days of our nearly-continuous observations. Re-analysis of
the 2009 MOST light curve revealed the presence of 3 similar dips. On the basis
of recent theoretical results, we tentatively conclude that the dips may
represent occultations of the small hot spots created by unstable accretion
tongues by hypothetical optically thick clumps.Comment: Printed in MNRA
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