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 . ...

... 2001 August 16 . Centaurus A: X-Rays from an Active Galaxy . ... CXO , NASA . ... Astronomers were not disappointed, as Centaurus A's appearance in x-rays makes its classification as an active galaxy easy to appreciate. ... Blasting toward the upper left corner of the picture, the jet seems to arise from the galaxy's bright central x-ray source -- suspected of harboring a black hole with a million or so times the mass of the Sun. ... About APOD | ... NASA Technical Rep.: ...

... Centaurus A: X Rays from an Active Galaxy . ... CXO , NASA Explanation: Its core hidden from optical view by a thick lane of dust, the giant elliptical galaxy Centaurus A was among the first objects observed by the orbiting Chandra X-ray Observatory . ... The diffuse high-energy glow represents gas throughout the galaxy heated to temperatures of millions of degrees C. At 11 million light-years distant in the constellation Centaurus , Centaurus A (NGC 5128) is the closest active galaxy . ...

... 773Veron-Cetty Veron . Quasars (brighter than absolute magnitude -23) 85221 . ... Active galaxies (fainter than -23) 21737 . VII/248 Quasars and Active Galactic Nuclei (12th Ed.) (Veron+ 2006) ================================================================================ Quasars and Active Galactic Nuclei (12th Ed.) Veron-Cetty M.P., Veron P. =2006A .. ... 374, 92 (Catalogue ) (11) Veron-Cetty M.P., Veron P., 2003, Astron. ...

As a service to the astronomical community, we are recalibrating all archival Hubble Space Telescope Faint Object Spectrograph UV and optical spectrophotometry of active galaxies and quasars in order to extract uniformly calibrated spectrophotometric data for further detailed scientific investigations. ... NGC 4151 CLOUD F . NGC 5548 . ... NGC 4395 . ... NGC 4486 . ... NGC 4486 JET KNOT-A . ... NGC 4486 CLOUD-A . ... NGC 3031 . ... NGC 1068 . ... NGC 1068 CLOUD A . ... 1413+117A . ... NGC 4151 . ...

... A radio galaxy is a galaxy that emits an unusually big amount of energy at radio wavelengths. ... Inside of each galaxy with an active nucleus (radio galaxies are among them) there must be a system of a "central machine" responsible for the colossal amount of the emitted energy from radio to gamma ranges. ... Sometimes a radio source in an active galaxy may flare again if the needed conditions appear (a new portion of matter would fall into the furnace of the "central machine"). ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... Risks Comparable to NEOs . ... The Increasing Rate of Discovery of Asteroids . ... Comet and Asteroid Collision Probabilities . ... Extreme albedo comets and the impact hazard (PDF Format) . ... Asteroid Impact Animations . ... Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids - 2002 . ... The Spaceguard Survey Report, 1992 (PDF) . Tsunami from Asteroid/Comet Impacts . ...

Black holes . ... Black holes are objects for which the gravitational attraction is so strong that nothing, not even light, can escape from it. ... The material inside a black hole is concentrated into a singularity: a single point of infinitely high density where space and time are infinitely distorted. ... The existence of such black holes has been inferred in cases where the black hole pulls gas of a companion star that orbits around it. ... Gravity's Fatal Atraction: Black Holes in The Universe. ...

... Tonight's Sky . ... The Magazine . ... Observing . ... Magazine . ... Product Reviews . ... View more active galactic nuclei . ... In the July 2013 article, Secrets of the brightest objects in the universe, I describe what astronomers currently know about quasars, which are the most luminous type of active galactic nuclei (AGNs). ... Get instant access to subscriber content on Astronomy.com! ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter. ...

... A tussle in the distant Universe. This Hubble Space Telescope image shows evidence for a merger between a quasar and a companion galaxy. The quasar is the bright object just beneath the image center, and the wisps of material around it are remains of a galaxy disrupted by the interaction between it and the quasar. ... Galactic Nuclei: Old Quasars? Quasars as Probes of the Distant Universe . ... Quasars. ... The name quasar is made up with parts of the words "quasi-stellar radio." ...