A soft barred galaxy with an active nucleus
Click for original image.
Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of two different surveys aimed at studying galaxies with what scientists call active galactic nuclei.
IC 486 lies right on the edge of the constellation Gemini (the Twins), around 380 million light-years from Earth. Classified as a barred spiral galaxy, it features a bright central bar-shaped structure from which its spiral arms unfurl, wrapping around the core in a smooth, almost ring-like pattern.
…At the galaxy’s center a noticeable white glow outshines the starlight around it. This is light given off by IC 486’s active galactic nucleus (AGN), powered by a supermassive black hole more than 100 million times the mass of the Sun. Every sufficiently large galaxy hosts a supermassive black hole at its center, but some of these black holes are particularly ravenous, marshaling vast amounts of gas and dust into swirling accretion discs from which they feed. The intense heat generated by the orbiting disc of material generates intense radiation up to and including X-rays, which can outshine the entire rest of the galaxy. In these cases, the galaxy is known as an active galaxy, with an AGN at its center.
For comparison, the relatively inactive supermassive black hole at the center of the Milky Way has a mass of about four million Suns, considerably smaller than IC 486’s. Why one is active and the other not however is not yet truly understood, though their different masses might provide part of the explanation.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Click for original image.
Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of two different surveys aimed at studying galaxies with what scientists call active galactic nuclei.
IC 486 lies right on the edge of the constellation Gemini (the Twins), around 380 million light-years from Earth. Classified as a barred spiral galaxy, it features a bright central bar-shaped structure from which its spiral arms unfurl, wrapping around the core in a smooth, almost ring-like pattern.
…At the galaxy’s center a noticeable white glow outshines the starlight around it. This is light given off by IC 486’s active galactic nucleus (AGN), powered by a supermassive black hole more than 100 million times the mass of the Sun. Every sufficiently large galaxy hosts a supermassive black hole at its center, but some of these black holes are particularly ravenous, marshaling vast amounts of gas and dust into swirling accretion discs from which they feed. The intense heat generated by the orbiting disc of material generates intense radiation up to and including X-rays, which can outshine the entire rest of the galaxy. In these cases, the galaxy is known as an active galaxy, with an AGN at its center.
For comparison, the relatively inactive supermassive black hole at the center of the Milky Way has a mass of about four million Suns, considerably smaller than IC 486’s. Why one is active and the other not however is not yet truly understood, though their different masses might provide part of the explanation.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News