... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2009 February 9 . Anemic Galaxy NGC 4921 at the Edge . Credit: NASA , ESA , K. Cook ( LLNL ) . Explanation: How far away is spiral galaxy NGC 4921? ... The magnificent spiral NGC 4921 has been informally dubbed anemic because of its low rate of star formation and low surface brightness . ... About APOD | ...

... Credit Copyright: Data - Hubble Legacy Archive , ESA , NASA ; Processing - Roberto Colombari Explanation: How far away is spiral galaxy NGC 4921? ... Since NGC 4921 is a member of the Coma Cluster of Galaxies , refining its distance would also allow a better distance determination to one of the largest nearby clusters in the local universe. The magnificent spiral NGC 4921 has been informally dubbed anemic because of its low rate of star formation and low surface brightness . ...

This site provides on-line access to publications, figures, and data tables related to an extensive multi-wavelength observational program to study distant galaxy clusters. ... Lori Lubin, Bev Oke, and Marc Postman have been studying a sample of 9 distant clusters (some taken from the PDCS) using the Keck 10m telescope, the HST, and the KPNO 4m (for IR imaging). ... A Study of Nine High-Redshift Clusters of Galaxies: I. The Survey, . ... A Study of Nine High-Redshift Clusters of Galaxies: II. ...

... Observatory . ... Science . ... Science Users Information > Science and Technical Meetings > Conferences 2009 > Galaxy Clusters in the Early Universe . ... Observing Facilities . ... Observing with ESO Telescopes . ... Data Handling and Products . ... Science Data Products Forum . ... Science Archive Facility . ... ESO Data . ... The meeting aims at bringing together theorists and observers to review our progress on finding, studying and understanding galaxy clusters in the early Universe. ...

home publications > mercury . ... Big Clusters, Tiny Galaxies . ... Astronomers struggle to understand why giant star clusters form in the tiniest of galaxies . ... These clusters are probably young versions of globular clusters, but they are commonly called super star clusters. Seven dwarf galaxies within 16 million light-years have formed super star clusters, with one of these galaxies, NGC 1569, possessing two young clusters. ... Super star clusters have a lot to tell us about star formation. ...

Astronotes Armagh Planetarium's Stellar Blog! ... Stars . ... Starbursts are short-lived events, stars are forming so quickly that the reservoirs of interstellar gas from which stars are coalescing would be used up on a timescale much shorter than the age of the galaxy . ... Strong stellar winds from giant new stars in the starburst region combine with the blasts of supernovae to push a mighty flood of extremely hot gas, a ?superwind? from the galaxy thousands of light years into intergalactic space. ...

... 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. ...

M1 image More About M1 Nice Color Picture . ... M16 image More About M16 HST image . ... M31 image More About M31 Nice Color Picture . ... M42 image ; M43 image More About M42/43 Nice Color CCD Picture . M51 image More About M51 Color Image of M51 M51 Supernova . M57 image More About M57 Nice Color CCD Picture Very Deep M57 Image . ... M81 image More About M81 M81 Supernova Ultraviolet Image of M81 More about Ultraviolet Imaging . M82 image More About M82 M82 False Color M82 True Color . ...

... December 13, 1997 . The Coma Cluster of Galaxies . ... The Coma Cluster of Galaxies pictured is one of the densest clusters known - it contains thousands of galaxies . Each of these galaxies house billions of stars - just as our own Milky Way Galaxy does. ... In fact, the Coma Cluster is so big it takes light millions of years just to go from one side to the other! Most galaxies in Coma and other clusters are ellipticals , while most galaxies outside of clusters are spirals . ...

... We have made observations of the Perseus cluster with the Westerbork Telescope at 610 MHz. ... Several newly detected sources are identified with cluster galaxies. ... No evidence is found for the existence of the previously reported ~ 65'x25' cluster halo, 3C 84B. Key words: radio galaxies - clusters - tailed radio sources buoyancy The Perseus Cluster of galaxies is one of the most fascinating systems accessible to extragalactic astronomers. ...

... About ATMoB . ... The Observing Committee is starting an Observing Awards Program to promote observing among the membership of the Amateur Telescope Makers of Boston. ... Participant must be a current member of the Amateur Telescope Makers of Boston . ... To qualify for your Observing Award Certificate, turn in your worksheet and drawings to an ATMoB Observing Committee member or observing@atmob.org . ... This Excel sheet has useful macros. ... Copyright (c) Amateur Telescope Makers of Boston, Inc. ...

... Tonight's Sky . ... Observing . ... Sky this Month . ... Gravitational wave search provides insights into galaxy evolution and mergers . ... Globular cluster NGC 2808, elliptical galaxy NGC 2986, and the Sextans Dwarf . ... Astronomy for Kids . ... In some photographs of galaxy clusters, why are the arcs of a lensed galaxy blue? ... Get instant access to subscriber content on Astronomy.com! ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter. ...

... Australian telescopes have helped the Hubble Space Telescope (HST) find thousands of new galaxies. ... Preliminary HST results were released today by NASA's Space Telescope Science Institute , as were the results from the Australian institutions. ... Called the Hubble Deep Field South , it complements the original Hubble Deep Field , another small patch in the northern sky. ... The Anglo-Australian Telescope has measured the distances of about 75 faint far-flung galaxies in the field. ...

DARK MATTER IN THE UNIVERSE Paul J. Green UNSEEN MASS: Astronomers studying the motions of stars and galaxies throughout the universe have long noticed a strange discrepancy. Stars move around galaxies as if pulled by ten times the matter that we can see. ... GRAVITATIONAL LENSING: Since dark matter by definition cannot be directly observed, several recent searches have instead exploited the predicted gravitational effects of its mass on the observed light from nearby stars. ...

... Ultraluminous X-ray sources (ULXs) are located in external galaxies, their X-ray luminosities (10 39 - 10 41 erg/s) are thousand times greater than those of brightest black holes in the Galaxy. ULXs may be supercritical accretion disks around black holes of stellar masses (~10 Solar masses) like that in SS433, or they may be a hypothetical intermediate-mass black holes (hundreds - thousands Solar masses) with standard accretion disks. ... 2) The ULX progenitors were ejected from the star clusters. ...

Rastorguev А.S. "Astronomical Distances" (Lecture course for postgraduates, 2009-2016) . Part 1. ... Trigonometric parallaxes of stars. Moving clusters distances. ... Photometric distances: general approach. Normal stars as "standard candles". ... Main Sequence fitting or distance scale of star clusters. ... Moving photospheres technique. Cepheid distance scale and P-L relations. RR Lyrae distance scale. ... Globular clusters luminosity function. ...

... Bad Astronomy . ... Bitesize Astronomy . ... The last step encompassed them all with galaxies , and how we discovered that the Milky Way was not the entire Universe. ... And just like those star clusters, there are different kinds of galaxy clusters. ... There are vast clusters of clusters, called superclusters, which contains hundreds of thousands or even millions of galaxies. ... Our own Galaxy has 400 billion stars in it, yet there are clusters out there with millions of galaxies like our own. ...

... The search for distant objects which can be both galaxies and quasars is one of the most important problems of observational astrphysics, because it allows one to determine cosmological parameters connected with the time of appearence and evolution of stellar systems, large scale structure of the Universe. ... Radio galaxies are important objects to be studied because they are sources of infrared-optical-ultraviolet continuum, emission lines and continual radio emission. ...

. F IGURE . 5. Relation between metallicity and (a) cluster Galactocentric distance and (b) distance from the Galactic plane. The straight lines are the rms regression fits for the thick-disk, entire Galaxy, and halo from top to bottom, respectively. The slopes of the lines yield the corresponding metallicity gradients. discussion in the text | previous figure | next figure .

... Here comes the SKA. ... HI Gas and Star Formation neutral atomic hydrogen gas cloud (HI) molecular gas cloud (H2) star formation Redshift, Observing the Past The Expanding Universe Hubble`s Law redshift velocity related to distance ... (due to light travel time) Hubble`s Law redshift velocity related to distance distance related to age (due to light travel time) Atmospheric Transmission optical gamma rays, X-rays ultravio let infrared radio ...