Modeling the Orbital Sampling Effect of Extrasolar Moons

The orbital sampling effect (OSE) appears in phase-folded transit light curves of extrasolar planets with moons. Analytical OSE models have hitherto neglected stellar limb darkening and non-zero transit impact parameters and assumed that the moon is on a circular, co-planar orbit around the planet. Here, we present an analytical OSE model for eccentric moon orbits, which we implement in a numerical simulator with stellar limb darkening that allows for arbitrary transit impact parameters. We also describe and publicly release a fully numerical OSE simulator (PyOSE) that can model arbitrary inclinations of the transiting moon orbit. Both our analytical solution for the OSE and PyOSE can be used to search for exomoons in long-term stellar light curves such as those by Kepler and the upcoming PLATO mission. Our updated OSE model offers an independent method for the verification of possible future exomoon claims via transit timing variations and transit duration variations. Photometrically quiet K and M dwarf stars are particularly promising targets for an exomoon discovery using the OSE.Comment: published in ApJ; 11 figures (8 b/w, 3 col); OSE simulator available at https://github.com/hippke/pyos

How Specialized is “too” Specialized? Outmigration and Industry Diversification in Nonmetropolitan Counties across America

Outmigration and industrial composition have separately been the focal points of a significant amount of research related to nonmetropolitan counties; however, few (if any) studies have explicitly looked at the relationship between the two topics. The primary objective of this research is to identify what industry specialization level is “too” specialized with regards to outmigration – that is, to determine the level where specialization begins to have a damaging effect on population change. County-level data from a variety of sources is used to explore the impact of both earnings-based and employment-based definitions of specialization on net migration in nonmetropolitan counties from 2000 – 2009. Two distinct techniques (ordinary least squares and average treatment effects) are then used to assess both the impact and causality of being “too specialized.” The results suggest that a variety of specialization thresholds exist across various industries, including some surprising positive influences of industry composition on migration rates.Outmigration, Nonmetropolitan, Industrial Specialization, Industrial Diversification, Community/Rural/Urban Development,

Parental participation in statutory child protection intervention in Scotland

In recent years there has been an increasing interest in understanding parental participation in the processes that characterise statutory child protection intervention. In part, this reflects a shift in thinking across western child protection systems, which has recognised that active parental involvement in intervention is more likely to lead to better outcomes for children at risk of abuse and / or neglect and a repositioning of child protection practices within broader discourses of service user participation. In this paper we present the findings of a small scale qualitative study which explored the experiences of twelve parents who were, at the time of the study, subject to statutory child protection intervention measures in Scotland. Parents reported intervention experiences as simultaneously negative and positive. The early stages of intervention and child protection case conferences were experienced as particularly distressing and confusing. The importance of the client-worker relationship emerged as central to meaningful participation and positive outcomes

Ultra Short Period Planets in K2: SuPerPiG Results for Campaigns 0-5

We have analyzed data from Campaigns 0-5 of the K2 mission and report 19 ultra-short-period candidate planets with orbital periods of less than 1 day (nine of which have not been previously reported). Planet candidates range in size from 0.7-16 Earth radii and in orbital period from 4.2 to 23.5 hours. One candidate (EPIC 203533312, Kp=12.5) is among the shortest-period planet candidates discovered to date (P=4.2 hours), and, if confirmed as a planet, must have a density of at least rho=8.9 g/cm^3 in order to not be tidally disrupted. Five candidates have nominal radius values in the sub-Jovian desert (R_P=3-11 R_E and P<=1.5 days) where theoretical models do not favor their long-term stability; the only confirmed planet in this range is in fact thought to be disintegrating (EPIC 201637175). In addition to the planet candidates, we report on four objects which may not be planetary, including one with intermittent transits (EPIC 211152484) and three initially promising candidates that are likely false positives based on characteristics of their light curves and on radial velocity follow-up. A list of 91 suspected eclipsing binaries identified at various stages in our vetting process is also provided. Based on an assessment of our survey's completeness, we estimate an occurrence rate for ultra-short period planets among K2 target stars that is about half that estimated from the Kepler sample, raising questions as to whether K2 systems are intrinsically different from Kepler systems, possibly as a result of their different galactic location.Comment: 13 pages, 8 figures, accepted to AJ on 2016 May 2

The Velocity Field of Quasar Broad Emission Line Gas

In this Letter, the broad emission line (BEL) profiles of superluminal quasars with apparent jet velocities, $\beta_{a}>10$, (ultraluminal QSOs, or ULQSOs hereafter) are studied as a diagnostic of the velocity field of the BEL emitting gas in quasars. The ULQSOs are useful because they satisfy a very strict kinematical constraint, their parsec scale jets must be propagating within $12^{\circ}$ of the line of sight. We know the orientation of these objects with great certainty. The large BEL FWHM, $\sim 3,000 \mathrm{km/s} - 6,000 \mathrm{km/s}$, in ULQSOs tend to indicate that the BEL gas has a larger component of axial velocity (either random or in a wind) along the jet direction than previously thought.Comment: To appear in ApJ Letter

The Economics of Small Worlds

We examine a simple economic model of network formation where agents benefit from indirect relationships. We show that small-world features—short path lengths between nodes together with highly clustered link structures—necessarily emerge for a wide set of parameters

Tidal Decay and Stable Roche-Lobe Overflow of Short-Period Gaseous Exoplanets

Many gaseous exoplanets in short-period orbits are on the verge or are in the process of Roche-lobe overflow (RLO). Moreover, orbital stability analysis shows tides can drive many hot Jupiters to spiral inevitably toward their host stars. Thus, the coupled processes of orbital evolution and RLO likely shape the observed distribution of close-in exoplanets and may even be responsible for producing some of the short-period rocky planets. However, the exact outcome for an overflowing planet depends on its internal response to mass loss, and the accompanying orbital evolution can act to enhance or inhibit RLO. In this study, we apply the fully-featured and robust Modules for Experiments in Stellar Astrophysics (MESA) suite to model RLO of short-period gaseous planets. We show that, although the detailed evolution may depend on several properties of the planetary system, it is largely determined by the core mass of the overflowing gas giant. In particular, we find that the orbital expansion that accompanies RLO often stops and reverses at a specific maximum period that depends on the core mass. We suggest that RLO may often strand the remnant of a gas giant near this orbital period, which provides an observational prediction that can corroborate the hypothesis that short-period gas giants undergo RLO. We conduct a preliminary comparison of this prediction to the observed population of small, short-period planets and find some planets in orbits that may be consistent with this picture. To the extent that we can establish some short-period planets are indeed the remnants of gas giants, that population can elucidate the properties of gas giant cores, the properties of which remain largely unconstrained.Comment: Accepted to "Celestial Mechanics and Dynamical Astronomy" special issue on tides. Several changes based on referee comments, including to the title of the paper. Some new analysis of non-conservative (but still stable) mass transfer as well. Article repository and data files linked to here -- http://www.astrojack.com/research

Tidal Effects on the Habitability of Exoplanets: The Case of GJ 581 d

Tides may be crucial to the habitability of exoplanets. If such planets form around low-mass stars, then those in the circumstellar habitable zone will be close enough to their host stars to experience strong tidal forces. Tides may result in orbital decay and circularization, evolution toward zero obliquity, a fixed rotation rate (not necessarily synchronous), and substantial internal heating. Due to tidal effects, the range of habitable orbital locations may be quite different from that defined by the traditional concept of a habitable zone (HZ) based on stellar insolation, atmospheric effects, and liquid water on a planet's surface. Tidal heating may make locations within the traditional HZ too hot, while planets outside the traditional zone could be rendered quite habitable due to tides. Here we consider these effects on the exoplanet GJ 581 d.Comment: 2 pages, 1 figure