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July - December 2014

Bonnsai: a Bayesian tool for comparing stars with stellar evolution models

Schneider, F. R. N.; Langer, N.; de Koter, A.; Brott, I.; Izzard, R. G.; Lau, H. H. B.

Powerful telescopes equipped with multi-fibre or integral field spectrographs combined with detailed models of stellar atmospheres and automated fitting techniques allow for the analysis of large number of stars. These datasets contain a wealth of i ...
Bonnsai: a Bayesian tool for comparing stars with stellar evolution models

Schneider, F. R. N.; Langer, N.; de Koter, A.; Brott, I.; Izzard, R. G.; Lau, H. H. B.

Powerful telescopes equipped with multi-fibre or integral field spectrographs combined with detailed models of stellar atmospheres and automated fitting techniques allow for the analysis of large number of stars. These datasets contain a wealth of i ...
MegaMorph - multiwavelength measurement of galaxy structure: physically meaningful bulge-disc decomposition of galaxies near and far

Vika, Marina; Bamford, Steven P.; Häußler, Boris; Rojas, Alex L.

Bulge-disc decomposition is a valuable tool for understanding galaxies. However, achieving robust measurements of component properties is difficult, even with high-quality imaging, and it becomes even more so with the imaging typical of large survey ...
Autonomous Real-time Detection of Plumes and Jets from Moons and Comets

Wagstaff, Kiri L.; Thompson, David R.; Bue, Brian D.; Fuchs, Thomas J.

Dynamic activity on the surface of distant moons, asteroids, and comets can manifest as jets or plumes. These phenomena provide information about the interior of the bodies and the forces (gravitation, radiation, thermal) they experience. Fast detec ...
Updated Radio Sigma-D Relation for Galactic Supernova Remnants

Pavlovic, M. Z.; Dobardzic, A.; Vukotic, B.; Urosevic, D.

We present the updated empirical radio surface-brightness-to-diameter (Sigma - D) relation for supernova remnants (SNRs) in our Galaxy. Our original calibration sample of Galactic SNRs with independently determined distances (Pavlovic et al. 2013, h ...
Hybrid methods in planetesimal dynamics: description of a new composite algorithm

Glaschke, P.; Amaro-Seoane, P.; Spurzem, R.

The formation and evolution of protoplanetary systems, the breeding grounds of planet formation, is a complex dynamical problem that involves many orders of magnitudes. To serve this purpose, we present a new hybrid algorithm that combines a Fokker- ...
Gravitational lens recovery with GLASS: measuring the mass profile and shape of a lens

Coles, Jonathan P.; Read, Justin I.; Saha, Prasenjit

We use a new non-parametric gravitational modelling tool - GLASS - to determine what quality of data (strong lensing, stellar kinematics, and/or stellar masses) are required to measure the circularly averaged mass profile of a lens and its shape. GL ...
Weak lensing using only galaxy position angles

Whittaker, Lee; Brown, Michael L.; Battye, Richard A.

We develop a method for performing a weak lensing analysis using only measurements of galaxy position angles. By analysing the statistical properties of the galaxy orientations given a known intrinsic ellipticity distribution, we show that it is pos ...
The Mass Distribution of Companions to Low-mass White Dwarfs

Andrews, Jeff J.; Price-Whelan, Adrian M.; Agüeros, Marcel A.

Measuring the masses of companions to single-line spectroscopic binary stars is (in general) not possible because of the unknown orbital plane inclination. Even when the mass of the visible star can be measured, only a lower limit can be placed on t ...
Type Ia Supernova Colors and Ejecta Velocities: Hierarchical Bayesian Regression with Non-Gaussian Distributions

Mandel, Kaisey S.; Foley, Ryan J.; Kirshner, Robert P.

We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II λ6355 spectral feature. We construct a new hierarchical Bayesian regressio ...
Constraining duty cycles through a Bayesian technique

Romano, P.; Guidorzi, C.; Segreto, A.; Ducci, L.; Vercellone, S.

The duty cycle (DC) of astrophysical sources is generally defined as the fraction of time during which the sources are active. It is used to both characterize their central engine and to plan further observing campaigns to study them. However, DCs a ...
Selecting asteroids for a targeted spectroscopic survey

Oszkiewicz, D. A.; Kwiatkowski, T.; Tomov, T.; Birlan, M.; Geier, S.; Penttilä, A.; Polińska, M.

Context. Asteroid spectroscopy reflects surface mineralogy. There are a few thousand asteroids whose surfaces have been observed spectrally. Determining their surface properties is important for many practical and scientific applications, such as de ...
Three-dimensional extinction mapping using Gaussian random fields

Sale, S. E.; Magorrian, J.

We present a scheme for using stellar catalogues to map the three-dimensional distributions of extinction and dust within our Galaxy. Extinction is modelled as a Gaussian random field, whose covariance function is set by a simple physical model of t ...
HerMES: point source catalogues from Herschel-SPIRE observations II

Wang, L.; Viero, M.; Clarke, C.; Bock, J.; Buat, V.; Conley, A.; Farrah, D.; Guo, K.; Heinis, S.; Magdis, G.; Marchetti, L.; Marsden, G.; Norberg, P.; Oliver, S. J.; Page, M. J.; Roehlly, Y.; Roseboom, I. G.; Schulz, B.; Smith, A. J.; Vaccari, M.; Zemcov, M.

The Herschel Multi-tiered Extragalactic Survey (HerMES) is the largest Guaranteed Time Key Programme on the Herschel Space Observatory. With a wedding cake survey strategy, it consists of nested fields with varying depth and area totalling ˜380 deg ...
Bayesian priors for the eccentricity of transiting planets

Kipping, David M.

Planets on eccentric orbits have a higher geometric probability of transiting their host star. By application of Bayes' theorem, we reverse this logic to show that the eccentricity distribution of transiting planets is positively biased. Adopting th ...
Obliquities of Kepler Stars: Comparison of Single- and Multiple-transit Systems

Morton, Timothy D.; Winn, Joshua N.

The stellar obliquity of a transiting planetary system can be constrained by combining measurements of the star's rotation period, radius, and projected rotational velocity. Here, we present a hierarchical Bayesian technique for recovering the obliq ...
On the Reliability of Microvariability Tests in Quasars

de Diego, José A.

Microvariations probe the physics and internal structure of quasars. Unpredictability and small flux variations make this phenomenon elusive and difficult to detect. Variance-based probes such as the C and F tests, or a combination of both, are popu ...
Orbit Determination with Mixture Observations of Multiple Objects

Wang, X.

In the operational orbit determination with optical measurements of space objects, some observations of different objects are tagged as the same object. For this kind of data, the orbit improvement according to the tag is failed because of the compo ...
Fast gain calibration in radio astronomy using alternating direction implicit methods: Analysis and applications

Salvini, Stefano; Wijnholds, Stefan J.

Context. Modern radio astronomical arrays have (or will have) more than one order of magnitude more receivers than classical synthesis arrays, such as the VLA and the WSRT. This makes gain calibration a computationally demanding task. Several altern ...
On the probability distribution function of the mass surface density of molecular clouds. II.

Fischera, Jörg

The probability distribution function (PDF) of the mass surface density of molecular clouds provides essential information about the structure of molecular cloud gas and condensed structures out of which stars may form. In general, the PDF shows two ...