The Apache Point Survey of Transit Lightcurves of Exoplanets (APOSTLE) observed 10 transits of XO-2b over a period of 3yr. We present measurements that confirm previous estimates of system parameters like the normalized semi-major axis (a/R_*_), stellar density ({rho}_*_), impact parameter (b), and orbital inclination (i_orb_). Our errors on system parameters like a/R_*_ and {rho}_*_ have improved by ~40% compared to previous best ground-based measurements. Our study of the transit times show no evidence for transit timing variations (TTVs) and we are able to rule out co-planar companions with masses >=0.20M_{Earth}_ in low order mean motion resonance with XO-2b. We also explored the stability of the XO-2 system given various orbital configurations of a hypothetical planet near the 2:1 mean motion resonance. We find that a wide range of orbits (including Earth-mass perturbers) are both dynamically stable and produce observable TTVs. We find that up to 51% of our stable simulations show TTVs that are smaller than the typical transit timing errors (~20s) measured for XO-2b, and hence remain undetectable.
For 7255 stars this catalog lists all values of the apparent and absolute radii from the literature. Data were compiled beginning 1950 up to 1985, including some data from 1986 and 1987. The catalogue was ordered by identification by HD number or BD number followed by variables with constellation names in alphabetical order, followed by other abbreviations. The HD and BD numbers were given priority 1 and 2 respectively over the other identifications. Hence variable stars can be found under the name of the constellation only when HD and BD numbers are lacking. The apparent magnitudes and spectral types are those reported by the authors, as they are basic data used in some methods for obtaining the stellar diameters.
We measure apparent velocities (v_app_) of the H{alpha} and H{beta} Balmer line cores for 449 non-binary thin disk normal DA white dwarfs (WDs) using optical spectra taken for the European Southern Observatory SN Ia progenitor survey (SPY). Assuming these WDs are nearby and comoving, we correct our velocities to the local standard of rest so that the remaining stellar motions are random. By averaging over the sample, we are left with the mean gravitational redshift, <v_g_>: we find <v_g_>=<v_app_>=32.57+/-1.17km/s. Using the mass-radius relation from evolutionary models, this translates to a mean mass of 0.647^+0.013^_-0.014_M_{sun}_. We interpret this as the mean mass for all DAs.
We analyze the 6.5yr all-sky data from the Fermi LAT restricted to gamma-ray photons with energies between 0.6-307.2GeV. We present a non-parametric reconstruction of the diffuse photon flux up to several hundred GeV, its all-sky spectral index map, and its angular power spectrum. We decompose the diffuse emission into a cloud-like abd a bubble-like component and analyze their spectra. Additionally, we wrote up a catalog of source candidates that includes 3106 sources. For each source we report the location in the sky, flux, spectral index, and possible associations with sources from the second and third Fermi source catalog.
In 1986 Svechnikov M.A. had published the "Catalogue of orbital elements, masses and luminosities" [1] of 246 eclipsing binary systems with known photometric and spectroscopic elements on comparatively early stages of their evolution (on the stage of the main sequence and during or after the "first change of mass") and belonging to DM, SD, DS, KE, KW, DW and AR evolutionary types (see lower) according to Svechnikov's classification [2,3,4]. However the representative eclipsing systems in this catalogue make up only a small share (about 5%) from discovered ones to all eclipsing variable stars of mentioned types (the general catalogue of variable stars [5] (which is called further GCVS IV) contains the information approximately of about 5000 eclipsing binary stars of different types). It is of a great interest for statistic research to give if only the approximate estimations of relative and absolute elements of those systems for which elements of the spectroscopic orbits are unknown and the direct calculation of their absolute characteristics is impossible. For this approximate estimation the statistic relations (mass - luminosity, mass - radius, mass - spectrum etc.) obtained for the components of different type systems [6-9] and a number of other statistic dependences which have been found from study of 246 eclipsing systems mentioned (for example, the dependence of orbital inclination I on the depth of main minimum A1, the dependence of the main component spectral classes for the KE- and KW-systems on the period P etc.) were used. For definition of the approximate elements it was used the information from GCVS IV about the morphological type of systems (EA, EB, EW), its period, the spectral classes of systems, amplitudes A1 and A2 of the main and second minima, duration of eclipse D1 and duration of constant light phase D2 in the main minimum etc., it was made the classification of eclipsing variable stars with the help of a simple test, worked out in [4], and the statistic dependences obtained for the stars of a given type was used later on the question about reliability of approximate relative and absolute elements which have been founded by this way was studied earlier in [8]. The accuracy of these elements is essentially higher for systems with certain spectra of main components (SP1). This fact was taken into account in catalogue by giving the essentially a higher weights to elements of those systems. There are about 1200 systems with the certain meaning SP1 in our catalogue, it is about 1/3 from all eclipsing systems in it. On the whole the elements (with different reability) for about 3800 eclipsing variable stars of DM, SD, DS, KE, KW and DW types are given in catalogue which makes up the overwhelming majority of eclipsing variable stars with the certain period from GCVS IV. Because of the possible mistakes in our classification wrong or incomplete data given in GCVS IV and also because of the fact that used statistic dependences for definition of elements have an approximate character, it should be expect that founded in catalogue the approximate elements for many systems are inaccurate and even wrong. By our estimation, elements will be grossly wrong for about 10-15% of systems given in this catalogue (which principally have a small weights), for about 20- 25% of systems the founded elements will turn out essentially different from veritable, however, we hope that for 60-70% of systems the photometric and absolute elements will turn out quite similar to elements which will be received the more exact methods later on. The elements, given in catalogue, may be used in the different statistic researches and also as an initial approximation for the calculation of photometric and absolute elements of these eclipsing stars with more exact methods.
The new data on the orbital elements, masses and luminosities have been collected for 31 pre-contact binary systems of short-periodic RS CVn type. The results of statistical treatment of the catalogue data pursue the goal of an accurate definition of the properties and evolutionary status of the given class systems. The ages of pre-contact systems have been estimated by isochrone method. Numerous comments and bibliographic references to the catalogue are accessible.
