Saturday, April 8, 2023

3948 - HUBBLE SPACE TELESCOPE - new discoveries?

 

-   3948 -  HUBBLE  SPACE  TELESCOPE -  new discoveries?     Hubble Space Telescope spots light from ancient wayward stars. Scientists are on a mission to determine the origin of these rogue stars, which they now think are even older than anticipated.

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------------  3948  -  HUBBLE  SPACE  TELESCOPE -  new discoveries?

-    The Hubble Space Telescope has imaged a glowing phenomenon called “intracluster light”, which is light emitted by wandering stars, which are not gravitationally bound to others.   Stars are typically very "social" things. Thanks to gravity, they're often found bound together in full-blown galaxies like our own Milky Way or much smaller star clusters.

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-    Spread throughout the universe are rogue stars that remain gravitationally untethered to others, wandering endlessly in the vastness of space.   The light from these stars, intracluster light, was first discovered in 1951 by Fritz Zwicky.  A new infrared survey by the Hubble Space Telescope has shed light on that faint glow.

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-    The infreared survey studied 10 galactic clusters, or gravitationally bound groups of galaxies, at distances as far as 10 billion light-years away. What researchers discovered in the data was that the ratio of intracluster light compared to the total light of the clusters is constant.

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-    That suggests that the wandering stars are billions of years old and not likely recently ejected from established galactic clusters through stripping, when massive gravitational tides pull material out of galaxies. If stripping were the main origin of wayward stars, scientists would expect to see the fraction of intracluster light increase over time compared to the light of galactic clusters.

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-    In their early formative years, galaxies might have been small and they bled stars easily because of a weaker gravitational grasp.  These strange stars may give scientists a glimpse of dark matter, the invisible material that makes up most of the matter in the universe and whose gravitational force holds galaxies together.

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-    Space is hard, the adage goes. And we'd extrapolate that sentiment to the classification of celestial objects.   A newly released image taken by the Hubble Space Telescope shows 'Z 229-15”, which, at first glance, simply appears to be a spiral galaxy, given its two spiraling arms of stars emanating from a bright core. But it's far, far more than that.

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-    “Z 229-15”  is one of those interesting celestial objects that you will find defined as several different things.  First, Z 229-15 is indeed a galaxy, which is a gravitationally bound collection of stars.

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-    Second, it's an active galactic nucleus.   An AGN is a region at the center of a galaxy that is exceptionally bright due to a supermassive black hole at its core. It's not the black hole itself that's so luminous, but rather all the material from the galaxy that has been trapped in a spinning disk around it, having been drawn toward the black hole by its intense gravitational pull.

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-     That disk heats up and emits massive amounts of energy across the electromagnetic spectrum, resulting in the brightness.  And this AGN is also a “quasar”, which is a specific subtype of AGN.

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-    The criteria for an AGN to be classified as a quasar include extreme brightness and a great distance away from Earth.   Z 229-15 is indeed very bright in the center. And given that it's 390 million light-years away from Earth, it's far enough away to be considered a quasar.

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-     Most quasars are so bright that they drown out our view of the stars in the galaxy. But when a quasar isn't that bright, allowing us to see stars, it's considered a Seyfert galaxy.

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                   April 6, 2023          HUBBLE  SPACE  TELESCOPE -  new discoveries?        3948                                                                                                                         

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--------------------- ---  Saturday, April 8, 2023  ---------------------------

 

 

 

 

         

 

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