Asteroseismic modeling of 16 Cyg A & B using the complete Kepler data set

Asteroseismology of bright stars with well-determined properties from parallax measurements and interferometry can yield precise stellar ages and meaningful constraints on the composition. We substantiate this claim with an updated asteroseismic analysis of the solar-analog binary system 16 Cyg A & B using the complete 30-month data sets from the Kepler space telescope. An analysis with the Asteroseismic Modeling Portal (AMP), using all of the available constraints to model each star independently, yields the same age ($t=7.0 \pm 0.3$ Gyr) and composition ($Z=0.021 \pm 0.002$, $Y_i=0.25 \pm 0.01$) for both stars, as expected for a binary system. We quantify the accuracy of the derived stellar properties by conducting a similar analysis of a Kepler-like data set for the Sun, and we investigate how the reliability of asteroseismic inference changes when fewer observational constraints are available or when different fitting methods are employed. We find that our estimates of the initial helium mass fraction are probably biased low by 0.02-0.03 from neglecting diffusion and settling of heavy elements, and we identify changes to our fitting method as the likely source of small shifts from our initial results in 2012. We conclude that in the best cases reliable stellar properties can be determined from asteroseismic analysis even without independent constraints on the radius and luminosity.Comment: 5 emulateapj pages, 1 table, 1 figure. ApJ Letters, accepte

Gyrfalcon Feeding Behaviour during the Nestling Period in Central West Greenland

We studied gyrfalcon (Falco rusticolus) food delivery and feeding behavior during the nestling period in central West Greenland during the 2000 and 2001 field seasons. We used time-lapse video cameras installed at three nests to record 2677.25 hours of nestling video. Ptarmigan delivered to nests were usually plucked prior to delivery and included the breast and superior thoracic vertebrae. Arctic hare leverets were rarely plucked and often delivered in parts. The most commonly delivered leveret part was the hind legs attached to the lower back. Passerines were rarely plucked and usually delivered whole. After feeding the young, adults removed 20.9% of prey items from the nest, which included items both with and without obvious muscle still attached. Prey delivery rates were similar among nests and increased as nestlings aged. Prey delivery frequency peaked in the morning and evening, with a distinct lull in the late evening and early morning hours. Male and female adults delivered a similar number of prey, though males typically delivered smaller prey than females. Gyrfalcons cached and re-delivered at least 9.1% of all items delivered, and one item was cached and retrieved three times.Durant les campagnes sur le terrain de 2000 et 2001 dans le centre du Groenland occidental, on a étudié chez le faucon gerfaut (Falco rusticolus) l'apport en nourriture et le comportement alimentaire pendant le séjour au nid. À l'aide de caméras vidéo filmant à intervalles, installées à trois nids, on a enregistré 2677,25 heures de vidéo au nid. Les lagopèdes apportés au nid étaient en général plumés avant d'y être déposés et comprenaient la poitrine et les vertèbres supérieures du thorax. Les jeunes lièvres arctiques étaient rarement pelés et étaient souvent apportés en morceaux. La partie du levraut la plus communément apportée était les pattes arrière rattachées au bas du dos. Les passereaux étaient rarement plumés et étaient en général livrés entiers. Après avoir nourri leurs petits, les adultes enlevaient du nid environ 20,9 % des parties des proies, comprenant des morceaux qui pouvaient comporter ou non du tissu musculaire évident. Le rythme de l'apport des proies était semblable parmi les divers nids et augmentait avec l'âge des oisillons. La fréquence de l'apport des proies passait par un maximum le matin et le soir, avec une accalmie très nette tard dans la soirée et au petit matin. Les mâles et les femelles adultes apportaient le même nombre de proies, mais les mâles livraient en général de plus petites proies que les femelles. Les faucons gerfauts dissimulaient dans une cache puis ressortaient par la suite au moins 9,1 % de tous les morceaux apportés, et un morceau a été dissimulé et ressorti trois fois

Phase-Dependent Properties of Extrasolar Planet Atmospheres

Recently the Spitzer Space Telescope observed the transiting extrasolar planets, TrES-1 and HD209458b. These observations have provided the first estimates of the day side thermal flux from two extrasolar planets orbiting Sun-like stars. In this paper, synthetic spectra from atmospheric models are compared to these observations. The day-night temperature difference is explored and phase-dependent flux densities are predicted for both planets. For HD209458b and TrES-1, models with significant day-to-night energy redistribution are required to reproduce the observations. However, the observational error bars are large and a range of models remains viable.Comment: 8 pages, 7 figures, accepted for publication in the Astrophysical Journa

Visualizing genetic constraints

Principal Components Analysis (PCA) is a common way to study the sources of variation in a high-dimensional data set. Typically, the leading principal components are used to understand the variation in the data or to reduce the dimension of the data for subsequent analysis. The remaining principal components are ignored since they explain little of the variation in the data. However, evolutionary biologists gain important insights from these low variation directions. Specifically, they are interested in directions of low genetic variability that are biologically interpretable. These directions are called genetic constraints and indicate directions in which a trait cannot evolve through selection. Here, we propose studying the subspace spanned by low variance principal components by determining vectors in this subspace that are simplest. Our method and accompanying graphical displays enhance the biologist's ability to visualize the subspace and identify interpretable directions of low genetic variability that align with simple directions.Comment: Published in at http://dx.doi.org/10.1214/12-AOAS603 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

HAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Star

Quantifying the evolution of stellar extreme ultraviolet (EUV, 100 -- 1000 $\overset{\circ}{A}$) emission is critical for assessing the evolution of planetary atmospheres and the habitability of M dwarf systems. Previous studies from the HAbitable Zones and M dwarf Activity across Time (HAZMAT) program showed the far- and near-UV (FUV, NUV) emission from M stars at various stages of a stellar lifetime through photometric measurements from the Galaxy Evolution Explorer (GALEX). The results revealed increased levels of short-wavelength emission that remain elevated for hundreds of millions of years. The trend for EUV flux as a function of age could not be determined empirically because absorption by the interstellar medium prevents access to the EUV wavelengths for the vast majority of stars. In this paper, we model the evolution of EUV flux from early M stars to address this observational gap. We present synthetic spectra spanning EUV to infrared wavelengths of 0.4 $\pm$ 0.05 M$_{\odot}$ stars at five distinct ages between 10 and 5000 Myr, computed with the PHOENIX atmosphere code and guided by the GALEX photometry. We model a range of EUV fluxes spanning two orders of magnitude, consistent with the observed spread in X-ray, FUV, and NUV flux at each epoch. Our results show that the stellar EUV emission from young M stars is 100 times stronger than field age M stars, and decreases as t$^{-1}$ after remaining constant for a few hundred million years. This decline stems from changes in the chromospheric temperature structure, which steadily shifts outward with time. Our models reconstruct the full spectrally and temporally resolved history of an M star's UV radiation, including the unobservable EUV radiation, which drives planetary atmospheric escape, directly impacting a planet's potential for habitability.Comment: 23 pages, 15 figures, accepted to Ap

Relationships Between Athlete Activist Identities and Resilience in College Athletes

Many high-profile athletes have engaged in athlete activism and continued to remain successful both in sport and activism. Although several barriers have been documented preventing athletes from engaging in activism (e.g., public criticism, status and job loss, withdrawal of funding, anticipated distress; Cunningham & Regan, 2012), activism itself has also been connected to several positive outcomes (e.g., improved confidence, self-concept, belief in change, agency, life meaning; Klar & Kasser, 2009; Rabkin, McElhiney, Harrington, & Horn, 2018). Indeed, both sport and activism provide opportunities for athlete activists to develop resilience. Therefore, the purpose of the present study was to examine the relationships between athletic identity (AI), activist identity and commitment (AIC), stress control mindset, and mental toughness. NCAA student-athletes (N = 204) reported low AIC overall. Regression models did not suggest that AI and AIC predict SCM or MT as expected, but correlations did provide evidence that SCM and MT are positively related. Possible explanations for these findings are discussed