From: LARRY KLAES (ljk4_at_msn.com)
Date: Fri Nov 17 2006 - 08:31:20 PST
Astrophysics, abstract
astro-ph/0611431
From: Suzanne Aigrain [view email]
Date: Tue, 14 Nov 2006 14:11:03 GMT (423kb)
The Monitor project: Searching for occultations in young open clusters
Authors: Suzanne Aigrain, Simon Hodgkin, Jonathan Irwin, Leslie Hebb, Mike
Irwin, Fabio Favata, Estelle Moraux, Frederic Pont
Comments: 26 pages, 10 figures, to appear in MNRAS. A PDF with full
resolution figures is available from this http URL
The Monitor project is a photometric monitoring survey of nine young
(1-200Myr) clusters in the solar neighbourhood to search for eclipses by
very low mass stars and brown dwarfs and for planetary transits in the light
curves of cluster members. It began in the autumn of 2004 and uses several 2
to 4m telescopes worldwide. We aim to calibrate the relation between age,
mass, radius and where possible luminosity, from the K-dwarf to the planet
regime, in an age range where constraints on evolutionary models are
currently very scarce. Any detection of an exoplanet in one of our youngest
targets (<=10Myr) would also provide important constraints on planet
formation and migration timescales and their relation to proto-planetary
disc lifetimes. Finally, we will use the light curves of cluster members to
study rotation and flaring in low-mass pre-main sequence stars.
The present paper details the motivation, science goals and observing
strategy of the survey. We present a method to estimate the sensitivity and
number of detections expected in each cluster, using a simple semi-analytic
approach which takes into account the characteristics of the cluster and
photometric observations, using (tunable) best-guess assumptions for the
incidence and parameter distribution of putative companions, and we
incorporate the limits imposed by radial velocity follow-up from medium and
large telescopes. We use these calculations to show that the survey as a
whole can be expected to detect over 100 young low and very low mass
eclipsing binaries, and approx. 3 transiting planets with radial velocity
signatures detectable with currently available facilities.
http://arxiv.org/abs/astro-ph/0611431
Astrophysics, abstract
astro-ph/0611448
From: David Bennett [view email]
Date: Tue, 14 Nov 2006 21:00:15 GMT (73kb)
Characterization of Gravitational Microlensing Planetary Host Stars
Authors: David P. Bennett, Jay Anderson, B. Scott Gaudi
The gravitational microlensing light curves that reveal the presence of
extrasolar planets generally yield the planet-star mass ratio and separation
in units of the Einstein ring radius. The microlensing method does not
require the detection of light from the planetary host star. This allows the
detection of planets orbiting very faint stars, but it also makes it
difficult to convert the planet-star mass ratio to a value for the planet
mass. We show that in many cases, the lens stars are readily detectable with
high resolution space-based follow-up observations. When the lens star is
detected, the lens-source relative proper motion can also be measured, and
this allows the masses of the planet and its host star to be determined and
the star-planet separation can be converted to physical units.
For the recently detected super-Earth planet, OGLE-2005-BLG-169Lb, we show
that the lens star will definitely be detectable with observations by the
Hubble Space Telescope (HST) unless it is a stellar remnant. Finally, we
show that most planets detected by a space-based microlensing survey are
likely to orbit host stars that will be detected and characterized by the
same survey.
http://arxiv.org/abs/astro-ph/0611448
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