3,917 research outputs found
Exoplanetary Transit Constraints Based Upon Secondary Eclipse Observations
Transiting extrasolar planets provide an opportunity to study the mass-radius
relation of planets as well as their internal structure. The existence of a
secondary eclipse enables further study of the thermal properties of the the
planet by observing at infrared wavelengths. The probability of an observable
secondary eclipse depends upon the orbital parameters of the planet,
particularly eccentricity and argument of periastron. Here we provide
analytical expressions for these probabilities, investigate their properties,
and calculate their values for the known extrasolar planets. We furthermore
quantitatively discuss constraints on existence and observability of primary
transits if a secondary eclipse is observed. Finally, we calculate the
a-posteriori transit probabilities of the known extrasolar planets, and we
present several case studies in which orbital constraints resulting from the
presence of a secondary eclipse may be applied in observing campaigns.Comment: 7 pages, 5 figures, 1 table; accepted for publication in PAS
Constraints on Secondary Eclipse Probabilities of Long-Period Exoplanets from Orbital Elements
Long-period transiting exoplanets provide an opportunity to study the
mass-radius relation and internal structure of extrasolar planets. Their
studies grant insights into planetary evolution akin to the Solar System
planets, which, in contrast to hot Jupiters, are not constantly exposed to the
intense radiation of their parent stars. Observations of secondary eclipses
allow investigations of exoplanet temperatures and large-scale exo-atmospheric
properties. In this short paper, we elaborate on, and calculate, probabilities
of secondary eclipses for given orbital parameters, both in the presence and
absence of detected primary transits, and tabulate these values for the forty
planets with the highest primary transit probabilities.Comment: 3 pages, 1 figure, 1 table; to appear in ASP Conf. Proceedings:
"Pathways Towards Habitable Planets" 2009, Barcelona, Spain (eds.: D. Gelino,
V. Coude du Foresto, I. Ribas
Observational Window Functions in Planet Transit Surveys
The probability that an existing planetary transit is detectable in one's
data is sensitively dependent upon the window function of the observations. We
quantitatively characterize and provide visualizations of the dependence of
this probability as a function of orbital period upon several observing
strategy and astrophysical parameters, such as length of observing run,
observing cadence, length of night, transit duration and depth, and the minimum
number of sampled transits. The ability to detect a transit is directly related
to the intrinsic noise of the observations. In our simulations of observational
window functions, we explicitly address non-correlated (gaussian or white)
noise and correlated (red) noise and discuss how these two noise components
affect transit detectability in fundamentally different manners, especially for
long periods and/or small transit depths. We furthermore discuss the
consequence of competing effects on transit detectability, elaborate on
measures of observing strategies, and examine the projected efficiency of
different transit survey scenarios with respect to certain regions of parameter
space.Comment: 16 pages, 11 figures, 8 tables; accepted for publication in Ap
Decomposing feature-level variation with Covariate Gaussian Process Latent Variable Models
The interpretation of complex high-dimensional data typically requires the
use of dimensionality reduction techniques to extract explanatory
low-dimensional representations. However, in many real-world problems these
representations may not be sufficient to aid interpretation on their own, and
it would be desirable to interpret the model in terms of the original features
themselves. Our goal is to characterise how feature-level variation depends on
latent low-dimensional representations, external covariates, and non-linear
interactions between the two. In this paper, we propose to achieve this through
a structured kernel decomposition in a hybrid Gaussian Process model which we
call the Covariate Gaussian Process Latent Variable Model (c-GPLVM). We
demonstrate the utility of our model on simulated examples and applications in
disease progression modelling from high-dimensional gene expression data in the
presence of additional phenotypes. In each setting we show how the c-GPLVM can
extract low-dimensional structures from high-dimensional data sets whilst
allowing a breakdown of feature-level variability that is not present in other
commonly used dimensionality reduction approaches
pp Elastic Scattering at LHC in a Nucleon-Structure Model
We predict pp elastic differential cross sections at LHC at c.m. energy 14
TeV and momentum transfer range |t| = 0 - 10 GeV*2 in a nucleon-structure
model. In this model, the nucleon has an outer cloud of quark-antiquark
condensed ground state, an inner shell of topological baryonic charge (r ~
0.44F) probed by the vector meson omega, and a central quark-bag (r ~ 0.2F)
containing valence quarks. We also predict elastic differential cross section
in the Coulomb-hadronic interference region. Large |t| elastic scattering in
this model arises from valence quark-quark scattering, which is taken to be due
to the hard-pomeron (BFKL pomeron with next to leading order corrections). We
present results of taking into account multiple hard-pomeron exchanges, i.e.
unitarity corrections. Finally, we compare our prediction of pp elastic
differential cross section at LHC with the predictions of various other models.
Precise measurement of pp elastic differential cross section at LHC by the
TOTEM group in the |t| region 0 - 5 GeV*2 will be able to distinguish between
these models.Comment: To be published in the Proceedings of the 12th International
Conference on Elastic and Diffractive Scattering, DESY, Hamburg. Presented by
M. M. Islam, May 200
Statistical analysis for thermometric sensors test program final report
Statistical models for regression analysis of thermometric sensor
Refining Exoplanet Ephemerides and Transit Observing Strategies
Transiting planet discoveries have yielded a plethora of information
regarding the internal structure and atmospheres of extra-solar planets. These
discoveries have been restricted to the low-periastron distance regime due to
the bias inherent in the geometric transit probability. Monitoring known radial
velocity planets at predicted transit times is a proven method of detecting
transits, and presents an avenue through which to explore the mass-radius
relationship of exoplanets in new regions of period/periastron space. Here we
describe transit window calculations for known radial velocity planets,
techniques for refining their transit ephemerides, target selection criteria,
and observational methods for obtaining maximum coverage of transit windows.
These methods are currently being implemented by the Transit Ephemeris
Refinement and Monitoring Survey (TERMS).Comment: 8 pages, 6 figures, accepted for publication in PAS
System Geometries and Transit / Eclipse Probabilities
Transiting exoplanets provide access to data to study the mass-radius
relation and internal structure of extrasolar planets. Long-period transiting
planets allow insight into planetary environments similar to the Solar System
where, in contrast to hot Jupiters, planets are not constantly exposed to the
intense radiation of their parent stars. Observations of secondary eclipses
additionally permit studies of exoplanet temperatures and large-scale
exo-atmospheric properties. We show how transit and eclipse probabilities are
related to planet-star system geometries, particularly for long-period,
eccentric orbits. The resulting target selection and observational strategies
represent the principal ingredients of our photometric survey of known
radial-velocity planets with the aim of detecting transit signatures (TERMS).Comment: 3 pages, 2 figures. Comments: To appear in the ASP Conference
Proceedings: Detection and Dynamics of Transiting Exoplanets; Proceedings of
Haute Provence Observatory Colloquium (23-27 August 2010); Edited by F.
Bouchy, R. F. Diaz, and C. Mouto
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