In order to measure the density of the Universe, it is necessary to sample a region that is larger than the scale on which the Universe becomes approximately homogeneous. ... When applied to clusters of galaxies we find a mass to luminosity ratio that implies a density of the Universe that is about 0.3 times the critical density. ... Thus the mass-to-muinosity ratio appears to vary with the size of the region measured, from 3 in the solar neighborhood to 30 in galaxies to 300 in clusters of galaxies. ...

Next: Cosmological Molecular Clouds Up: HST and the Previous: Cepheids in NGC . ... Recent calibrations of stellar surface brightness derived by modern observational interferometry show that the Cepheid PLC relations turn out to be much less affected by abundance effects than PL ones. Extragalactic Cepheid distances revisited by a calibrated PLC (V, V-Ic) relation indicate some significant systematic shifts affecting current PL determinations achieved by ground-based and HST photometry. ...

THE ARGUMENT AGAINST LONG EXTRAGALACTIC DISTANCE SCALE Gaseous discs of S0 -- Sd galaxies appears to be gravitationally stable or close to stability. Dependence of the gravitational stability parameter of gaseous disc $M_g/M_c$ upon the color index $(B-V)^0_T$ which reflects a relative number of young stars, is found. Here $M_g$ is total mass of gas in a galaxy, $M_c$ - mass of gas which corresponds to marginal stability of gaseous disc at distances from center. ...

... 2.3 Establishing the Extragalactic Distance Scale . ... 2.3.2 The Second Rung: Distances to stellar clusters . ... 2.3.4 Distances to Local Group Galaxies . ... The Luminosity Function of Planetary Nebulae . ... 3.2.2 Clusters of Galaxies . ... 4.2 Evidence for Dark Matter as a Function of Scale Size . ... 4.3 Other Dark Matter Indicators for Galaxies . ... What is the nature of the large-scale distribution of matter in the universe as traced by the three-dimensional galaxy distribution? ...

... Subject and Problems of Stellar Astronomy. ... Plane of Galaxy, Methods of Its Location Determination. ... Stars Distances. ... Other Methods of Stars Distances Determination. ... Tangential Velocities, Their Determination by Self-Motions. ... Determination of Solar Apex and Spatial Velocity by Radial and Spatial Velocities of Stars. ... Features of Orientation and Parameters of Peculiar Stellar Velocities Ellipsoid. ... General and Selective Light Absorption in Galaxy. ... Darc Clouds in Galaxy. ...

... Future seminars . P a s t seminars . Seminar council . ... A.F. Zakharov (Institute of Theoretical and Experimental Physics) . ... Different regimes of gravitational lensing depend on masses of lens and correspond roughly an angular distance between images. If a gravitational lens has a typical stellar mass, this regime is named as microlensing because a typical angular distance between images is about microarcseconds in the case if sources and lenses are located at cosmological distances. ...

... Flux density at 1 GHz (/Jy): 28 . ... Radio: Shell, brightest to the S. Optical: Filaments correspond well to the radio shell, brightest in SE. X-ray: Brightest to NW, with point source near centre. Point sources: Central, variable X-ray source, and nearby pulsar. ... Molonglo at 408 MHz (3') and Parkes 64-m at 5 GHz (4'). ADS . ... ASCA observations of compact X-ray source. ... X-ray variability of central source. ... ATCA at 1.4 GHz (50''), including H I absorption to central source. ...

... We can investigate projection of this distribution onto the celestial sphere in two ways: in terms of lines of constant SN frequencies per one square degree for all galaxies from the sample (Figure 36 ), and in terms of constant GW amplitudes at a given SN frequency per square degree (Figure 44 ). ... Figure 45: The sky distribution of the total supernova frequency from nearby galaxies in terms of lines of equal frequencies per square degree. ...

Determination of the physical parameters of molecular clouds Riccardo Cesaroni INAF­Osservatorio Astrofisico di Arcetri, Firenze, Italy E-mail: cesa@arcetri.astro.it The most common methods to derive some of the physical parameters of Galactic molecular clouds are described in this lecture. Special attention is devoted to the derivation of the (column) density, mass, and temperature. ... In particular, we will discuss the derivation of the velocity field, temperature, (column) density, and mass. ...

... public class EDM . ... Euclidean Distance Map: The value of each pixel is the distance to the nearest background pixel (for background pixels, the EDM is 0) - Ultimate Eroded Points (UEPs) are maxima of the EDM. ... static int . ... Unit in old make16bitEDM: this pixel value corresponds to a distance of one pixel. static int . ... int . ... For compatibility with previous versions of ImageJ only. public FloatProcessor makeFloatEDM ( ImageProcessor ip, int backgroundValue, boolean edgesAreBackground)...

Problem Set 2 - Cosmology­A3002 ­Due on or before November 7th. Can be sent via internal mail (Brian Schmidt, RSAA) use H0=70 km/s/Mpc, M=0.27, =0.73, w=-1 for all problems. ... Finish off your Monte Carlo simulation by selecting objects at random redshifts from 0<z<0.1, assuming that they have a mean absolute magnitude of M=-19.5 with a dispersion 0.2 magnitudes. ... Problem 2.1 (2 pt): In class we described the scale at which material can collapse in the Universe as the Jeans' length. ...

The database contains references to the papers, data files and links to the Internet resources related to measurements and calculations of the optical constants in the wavelength interval from X-rays to radio domain. ... References to some useful books and reviews on the subject (e.g. the classical handbooks edited by E.D.Palik) and links to Internet collections of optical constants and personal WWW pages with related software were also placed in the database. You have arrived at our welcome page. ...

. F IGURE . 10. Dependence of cluster metallicity on (a) Galactocentric distance and (b) distance from the Galactic plane. The filled and open circles correspond to the young and old halos, respectively, and the straight lines are the corresponding rms regressions. The small square shows the old-halo cluster excluded from computations based on a 3 criterion. discussion in the text | privious figure | next figure .

... The expansion is measured as a number called the Hubble Constant . ... Our value is about 20% lower than the one got with the Hubble Space Telescope in 1994," said Dr Jim Lovell, leader of the team that made the measurement. The Hubble Constant is named after American astronomer Edwin Hubble, who in the 1920s found that other galaxies were moving away from ours. ... The Hubble Constant links the galaxy's distance with its speed." ... A short run-down on the Hubble Constant: . ...

... LDN 988: Dark Nebula in Cygnus . ... Credit Copyright: Bob Franke Explanation: Obscuring the rich starfields of northern Cygnus, dark nebula LDN 988 lies near the center of this cosmic skyscape . ... Stars are forming within LDN 988 , part of a larger complex of dusty molecular clouds along the plane of our Milky Way galaxy sometimes called the Northern Coalsack. ... Publications with keywords: Cygnus - dark nebula - star formation . Publications with words: Cygnus - dark nebula - star formation . ...

... Science Users Information > Observing with ESO Telescopes > Phase 2 Preparation > Observing conditions . ... Service Mode Philosophy . ... The following definitions of the observing conditions are common between Phase 1 preparation and Phase 2 preparation, as well as between Service Mode and Visitor Mode observations. ... There are additional Service Mode Policies and Service Mode Guidelines regarding the observing conditions. ... Seeing (Phase 1) and Image quality (Phase2) constraints . ... Moon . ...

Альтернативный форум . Scientific.ru Все форумы . ... Time (@) - 13.04.2007 09:15 . Re: Anisotropy in the Hubble constant as observed in the HST Extragalactic Distance Scale Key Project results . x203a; x203a; x203a; в ответ на: Anisotropy in the Hubble constant as observed in the HST Extragalactic Distance Scale Key Project results Котофеич . ... Re: Anisotropy in the Hubble constant as observed in the HST Extragalactic Distance Scale Key Project results Котофеич, 13.04.2007 13:37 . ...

... The physical data page presents data about the objects themselves. ... ( 0 ) Mercury I Sun 57910 87.97 7.00 0.21 - - ( 0 ) Venus II Sun 108200 224.70 3.39 0.01 - - ( 0 ) Earth III Sun 149600 365.26 0.00 0.02 - - ( 0 ) Mars IV Sun 227940 686.98 1.85 0.09 - - ( 0 ) Jupiter V Sun 778330 4332.71 1.31 0.05 - - ( 0 ) Saturn VI Sun 1429400 10759.50 2.49 0.06 - - ( 0 ) Uranus VII Sun 2870990 30685.00 0.77 0.05 Herschel 1781 ( 0 ) Neptune VIII Sun 4504300 60190.00 1.77 0.01 Adams ( 9 ) 1846 ( 0 )...

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The ESA/ESO Astronomy Exercise Series 2 . The Distance to Messier 100 as Determined by Cepheid Variable Stars . ... The small variations in distance to the individual Cepheid variable stars in the Cloud are negligible compared with the much larger distance to the SMC. ... In this way Cepheid variable stars can be used as one of the 'standard candles' in the Universe that act either as distance indicators themselves or can be used to calibrate (or set the zero point for) other distance indicators. ...