In this brief communication we provide the rationale for, and the outcome of the International Astronomical Union (IAU) resolution vote at the XXIX th General Assembly in Honolulu, Hawaii, in 2015, on recommended nominal conversion constants for selected solar and planetary properties. The problem addressed by the resolution is a lack of established conversion constants between solar and planetary values and SI units: a missing standard has caused a proliferation of solar values (e.g., solar radius, solar irradiance, solar luminosity, solar effective temperature and solar mass parameter) in the literature, with cited solar values typically based on best estimates at the time of paper writing. As precision of observations increases, a set of consistent values becomes increasingly important. To address this, an IAU Working Group on Nominal Units for Stellar and Planetary Astronomy formed in 2011, uniting experts from the solar, stellar, planetary, exoplanetary and fundamental astronomy, as well as from general standards fields to converge on optimal values for nominal conversion constants. The effort resulted in the IAU 2015 Resolution B3, passed at the IAU General Assembly by a large majority. The resolution recommends the use of nominal solar and planetary values, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only, not as the true solar/planetary properties or current best estimates. Authors and journal editors are urged to join in using the standard values set forth by this resolution in future work and publications to help minimize further confusion.

We report results from a large Hubble Space Telescope project to observe a significant (∼34,000) ensemble of main-sequence stars in the globular cluster 47 Tucanae with a goal of defining the frequency of inner orbit, gas giant planets. Simulations based on the characteristics of the 8.3 days of time series data in the F555W and F814W Wide Field Planetary Camera 2 (WFPC2) filters show that ∼17 planets should be detected by photometric transit signals if the frequency of hot Jupiters found in the solar neighborhood is assumed to hold for 47 Tuc. The experiment provided high-quality data sufficient to detect planets. A full analysis of these WFPC2 data reveals ∼75 variables, but no light curves resulted for which a convincing interpretation as a planet could be made. The planet frequency in 47 Tuc is at least an order of magnitude below that for the solar neighborhood. The cause of the absence of close-in planets in 47 Tuc is not yet known; presumably the low metallicity and/or crowding of 47 Tuc interfered with planet formation, with orbital evolution to close-in positions, or with planet survival.

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The 24.6 day eclipsing binary AI Phe contains two sharp-lined stars of comparable luminosity which undergo total eclipse, and yet are well separated. Radial velocity, photometric, and ultraviolet observations of this star have been remodeled using our improved version of the Wilson-Devinney code on the University of Calgary's Cyber 205 and Myrias SPS-2 computers. This version now has a new atmospheres option which makes use of Kurucz' model atmospheres to approximate the surface fluxes of the two stars. With the option, light curve fitting is now demonstrably improved for optical wavelengths. Rough empirical corrections result in still further improvement, with smaller discrepancies in U and u than are found using either the blackbody approximation or the previously used (Carbon-Gingerich) atmospheres option. For a specified temperature, wavelength, and logg, interpolation is performed within a table of values representing the ratio of blackbody to stellar atmosphere flux. The model atmosphere option simulates fluxes in Strömgren uvby or Johnson UAEK bandpasses, as well as in other bandpasses with widths A log X = 0.1 in the range 0.316 to 3.550 pm, and A log X = 0.05 in the UV (at 10 specified wavelengths from 0.100 to 0.282 ^m). The limb darkening of the hotter component in the far UY as it undergoes total eclipse is also investigated and compared with Kurucz models.