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Surface brightness
About: Surface brightness is a research topic. Over the lifetime, 6498 publications have been published within this topic receiving 274882 citations.
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TL;DR: In this paper, exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening are presented for the HST observations of HD 209458, showing that the ratio of the planetary to stellar radii is 0.1207+-0.0003.
Abstract: We present exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening. In the limit that the planet radius is less than a tenth of the stellar radius, we show that the exact lightcurve can be well approximated by assuming the region of the star blocked by the planet has constant surface brightness. We apply these results to the HST observations of HD 209458, showing that the ratio of the planetary to stellar radii is 0.1207+-0.0003. These formulae give a fast and accurate means of computing lightcurves using limb-darkening coefficients from model atmospheres which should aid in the detection, simulation, and parameter fitting of planetary transits.
2,370 citations
TL;DR: In this paper, the exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening were presented, and the authors applied these results to the Hubble Space Telescope observations of HD 209458, showing that the ratio of the planetary to stellar radii is 0.1207 ± 0.0003.
Abstract: We present exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening. In the limit that the planet radius is less than a tenth of the stellar radius, we show that the exact light curve can be well approximated by assuming the region of the star blocked by the planet has constant surface brightness. We apply these results to the Hubble Space Telescope observations of HD 209458, showing that the ratio of the planetary to stellar radii is 0.1207 ± 0.0003. These formulae give a fast and accurate means of computing light curves using limb-darkening coefficients from model atmospheres that should aid in the detection, simulation, and parameter fitting of planetary transits.
2,253 citations
Princeton University1, Ohio State University2, Fermilab3, University of Chicago4, University of Pittsburgh5, University of Washington6, University of Tokyo7, University of Arizona8, Johns Hopkins University9, United States Department of the Navy10, Rensselaer Polytechnic Institute11, Carnegie Mellon University12, Rochester Institute of Technology13, Drexel University14, National Institutes of Natural Sciences, Japan15
TL;DR: In this article, the authors describe the algorithm that selects the main sample of galaxies for spectroscopy in the Sloan Digital Sky Survey (SDSS) from the photometric data obtained by the imaging survey.
Abstract: We describe the algorithm that selects the main sample of galaxies for spectroscopy in the Sloan Digital Sky Survey (SDSS) from the photometric data obtained by the imaging survey. Galaxy photometric properties are measured using the Petrosian magnitude system, which measures flux in apertures determined by the shape of the surface brightness profile. The metric aperture used is essentially independent of cosmological surface brightness dimming, foreground extinction, sky brightness, and the galaxy central surface brightness. The main galaxy sample consists of galaxies with r-band Petrosian magnitudes r ≤ 17.77 and r-band Petrosian half-light surface brightnesses μ50 ≤ 24.5 mag arcsec-2. These cuts select about 90 galaxy targets per square degree, with a median redshift of 0.104. We carry out a number of tests to show that (1) our star-galaxy separation criterion is effective at eliminating nearly all stellar contamination while removing almost no genuine galaxies, (2) the fraction of galaxies eliminated by our surface brightness cut is very small (~0.1%), (3) the completeness of the sample is high, exceeding 99%, and (4) the reproducibility of target selection based on repeated imaging scans is consistent with the expected random photometric errors. The main cause of incompleteness is blending with saturated stars, which becomes more significant for brighter, larger galaxies. The SDSS spectra are of high enough signal-to-noise ratio (S/N > 4 per pixel) that essentially all targeted galaxies (99.9%) yield a reliable redshift (i.e., with statistical error less than 30 km s-1). About 6% of galaxies that satisfy the selection criteria are not observed because they have a companion closer than the 55'' minimum separation of spectroscopic fibers, but these galaxies can be accounted for in statistical analyses of clustering or galaxy properties. The uniformity and completeness of the galaxy sample make it ideal for studies of large-scale structure and the characteristics of the galaxy population in the local universe.
1,933 citations
TL;DR: In this article, the population of galactic disks expected in current hierarchical clustering models for structure formation was studied and a rotationally supported disk with exponential surface density profile was assumed to form with a mass and angular momentum which are fixed fractions of those of its surrounding dark halo.
Abstract: We study the population of galactic disks expected in current hierarchical clustering models for structure formation. A rotationally supported disk with exponential surface density profile is assumed to form with a mass and angular momentum which are fixed fractions of those of its surrounding dark halo. We assume that haloes respond adiabatically to disk formation, and that only stable disks can correspond to real systems. With these assumptions the predicted population can match both present-day disks and the damped Lyman alpha absorbers in QSO spectra. Good agreement is found provided: (i) the masses of disks are a few percent of those of their haloes; (ii) the specific angular momenta of disks are similar to those of their haloes; (iii) present-day disks were assembled recently (at z 3kpc/h and about 10% at r>10kpc/h. The cross-section for absorption is strongly weighted towards disks with large angular momentum and so large size for their mass. The galaxy population associated with damped absorbers should thus be biased towards low surface brightness systems.
1,924 citations
TL;DR: In this paper, the authors describe the algorithm that selects the main sample of galaxies for spectroscopy in the Sloan Digital Sky Survey from the photometric data obtained by the imaging survey.
Abstract: We describe the algorithm that selects the main sample of galaxies for spectroscopy in the Sloan Digital Sky Survey from the photometric data obtained by the imaging survey. Galaxy photometric properties are measured using the Petrosian magnitude system, which measures flux in apertures determined by the shape of the surface brightness profile. The metric aperture used is essentially independent of cosmological surface brightness dimming, foreground extinction, sky brightness, and the galaxy central surface brightness. The main galaxy sample consists of galaxies with r-band Petrosian magnitude r < 17.77 and r-band Petrosian half-light surface brightness < 24.5 magnitudes per square arcsec. These cuts select about 90 galaxy targets per square degree, with a median redshift of 0.104. We carry out a number of tests to show that (a) our star-galaxy separation criterion is effective at eliminating nearly all stellar contamination while removing almost no genuine galaxies, (b) the fraction of galaxies eliminated by our surface brightness cut is very small (0.1%), (c) the completeness of the sample is high, exceeding 99%, and (d) the reproducibility of target selection based on repeated imaging scans is consistent with the expected random photometric errors. (abridged)
1,800 citations