Star formation is often best manifested by bright H II regions.These are regions of hydrogen which have been ionized by ultraviolet photons which are emitted from massive stars (typically stars more than 20 times the mass of the Sun). ... A narrowband filter image centered on this wavelength will then readily reveal these H II regions and hence the current sites of star formation in a galaxy, The luminous blobs that can be seen here are all H II regions . ... NGC 3558 Visual . NGC 3558 Infrared . ...

... Resembling a gigantic hubcap in space, a 3,700 light-year-diameter dust disk encircles a 300 million solar-mass black hole in the center of the elliptical galaxy NGC 7052. ... Because the front end of the disk eclipses more stars than the back, it appears darker. ... Despite its size, the disk is 100 times less massive than the black hole. ... The bright spot in the center of the disk is the combined light of stars that have crowded around the black hole due to its strong gravitational pull. ...

... Credit: William Pounds Explanation: It's clear who is the biggest star in this binary system. Based on recent results , this artist's vision of the double star Phi Persei , 720 light years away, shows a bright, rapidly rotating massive star surrounded by a disk of gas. A small companion star orbits 100 million miles away. ... Astronomers consider the ultimate fate of such mass-exchanging, interacting binary systems an open question and a challenge for present theories of stellar evolution . ...

Galileo showed convincingly that heavy objects fell no faster that light ones. ... If an iron ball was pulled down with a much greater force than a wooden one of the same size, why didn't it fall any faster? ... 1) It is harder to lift. ... It is the fact that the loaded wagon has a greater mass that gives it a larger inertia , a larger tendency to oppose any change in its state of rest or of constant motion in a straight line. ... One important quantity was the body mass of the astronauts. ...

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... 2006 December 19 . Massive Stars in Open Cluster Pismis 24 . Credit: NASA , ESA and J. M. ApellАniz ( IAA , Spain). Explanation: How massive can a normal star be? Estimates made from distance, brightness and standard solar models had given one star in the open cluster Pismis 24 over 200 times the mass of our Sun, making it a record holder. ... Component stars would still remain near 100 solar masses, making them among the more massive stars currently on record. ... About APOD | ...

Pulsars can be used to study the strong nuclear force. The density of matter at the center of neutron stars is one or two orders of magnitude larger than the density of atomic nuclei. ... Very "soft" EOSs predict lower pressures for a given density, i.e., highly compressible matter. ... If more precise measurements can confirm this high value, then many model EOSs for dense matter can be ruled out. ... Another way of studying the behavior of super-dense matter is to find fast pulsars. ...

Next: Ejectors in Massive Binary Previous: Artificial Galaxy: Full Matrix . The first version of the Scenario Machine was aimed especially at the simulation of massive binary star evolution. ... First, there is a large class of intermediate mass binaries (say, consisting initially of 8 + 5 solar masses) that can also produce NS and thus lead to the formation of a bright X-ray source. ... Next: Ejectors in Massive Binary Previous: Artificial Galaxy: Full Matrix Mike E. Prokhorov . ...

... If the mass of the collapsing star is more than three solar masses, however, no force can prevent it from collapsing completely to become a black hole. What is a black hole? Mini black holes . ... For Further Reading About Black Holes A black hole is a region of space in which the pull of gravity is so strong that nothing can escape. ... A black hole with a mass less than three solar masses would not form on its own; its gravity is too weak to cause it to completely collapse in on itself. ...

... The difference is that inertia is an inherent property of matter, while weight also depends on gravity. ... They use gravity, balancing its force on the astronaut's body against a calibrated spring or against the force of gravity on some calibrated weights. ... Using scales and the local force of gravity, one can determine gravitational mass; or else, one might dispense with gravity, like the astronauts aboard Skylab, sand measure the "inertial mass," and in principle they may differ. ...

... Tonight's Sky . ... Behemoth black hole found in an unlikely place . ... Ancient super-bright quasar with massive black hole found . ... Quasars supermassive black holes found at the center of distant massive galaxies are the most luminous beacons in the sky. ... An international team of astronomers, including Carnegie s Yuri Beletsky, has discovered the brightest quasar ever found in the early universe, which is powered by the most massive black hole observed for an object from that time. ...

... HUBBLE UNCOVERS DUST DISK AROUND A MASSIVE BLACK HOLE . Resembling a gigantic hubcap in space, a 3,700 light-year-diameter dust disk encircles a 300 million solar-mass black hole in the center of the elliptical galaxy NGC 7052. ... Because the jets in NGC 7052 are not perpendicular to the disk, it may indicate that the black hole and the dust disk in NGC 7052 do not have a common origin. ... NGC 7052 is located in the constellation of Vulpecula, 191 million light-years from Earth. ...

What happens to a star heavier than five solar masses? ... Stars about ten solar masses probably behave like our five solar mass star until they reach the end of core-helium burning. ... The Crab nebula was formed after a massive explosion ripped a star apart in 1054. ... Today, the glowing outer layers of the star are still rushing away from a tiny star in the centre. ... An incredible explosion rips through the outer layers of the star, releasing colossal amounts of energy in a supernova explosion. ...

... The hot component shows very spectacular activity: irregular outbursts accompanied by fast, massive outflows and jets. ... Diffraction-limited images for both components of CH Cyg binary system were reconstructed using visible speckle interferometry at BTA 6-m telescope (Fig.1). The orbital period 15.6 years and masses: 2.0 Msun and 0.7 Msun for red giant and white dwarf, respectively were derived from angular distance (0.042") and magnitude difference (2 m ) of the components. ... Fig.1. ...

B?rbel Koribalski (ATNF) + HIPASS and ZOA teams . The properties shown below were derived from the measurd HI properties. Displayed here are the Local Group velocities of all sources from -300 to +8000 km/s (bins are 100 km/s). Displayed here are the distances of all sources (assuming Ho = 75 km/s/Mpc). ... Displayed here are the HI masses of all sources (assuming point source distribution). Extended galaxies and pairs/groups need to be re-measured. ...

... Centaurus A : 15,000,000 light years away, in the constellation Centaurus, the closest AG to Earth . ... Astronomers think that the reason for the unusual shape of this galaxy is because hundreds of millions of years ago two galaxies, one dusty spiral and one bright ellipictal, collided causing a massive black hole in the middle and bright emmision of light. ... Andromeda galaxy: 2.8 million light years away, closest spiral galaxy to earth, farthest object one can see without a telescope. ...

... Stars . ... Cepheid variable stars have been known since the 18th century. ... Regularly brightening to a peak over days, weeks or months before fading these variable stars were remarkable curiosities to astronomers in past centuries.€а The term Cepheid is taken from the star Delta Cephei in the constellation of Cepheus, which was identified as variable€а in 1784 by the teenaged prodigy John Goodricke (1764-96). ... Tweets that mention Cepheids: Inconstant Stars which break the rules | ...

... Bad Astronomy . ... Every few months, one of a series of questions comes up on the USENET group sci.astro involving tides, or the rotation of the Moon, or the recession of the Moon from the Earth. ... Why the Moon's rotation period is the same as the length of time it takes to orbit the Earth (same as number 1, but phrased differently). ... But when this happens, the time it takes for the Earth to rotate once will be slowed to exactly the same time it takes for the Moon to go around the Earth once! ...

Class 1 Introduction, Background History of Modern Astronomy The Night Sky, Eclipses and the Seasons Kepler's Laws Newtonian Gravity General Relativity Matter and Light Telescopes Class 2 Solar System Characteristics Formation Exosolar Planets Class 3 Stars The S un Stellar Evolution of Low and High Mass Stars Deaths of Stars Exotic Stars Class 4 Galaxies Galaxy Classification Formation of Galaxies Galactic ... Low mass stars live and die differently than high mass stars. ...

Supernovae are simply stars which explode. ... To understand supernovae, we need to understand stars. ... In this stage our Sun will swell up hundreds of times its current size, swallowing the Earth, and glowing hundreds of times brighter than it is now. ... Stars more than 10 times the mass of our sun have much more exciting lives. ... A Type II supernova to be precise. ... Since 1995 two teams have been discovering these objects: Our team, the High-Z SN Search, and the Supernova Cosmology Project. ...