Tuesday, February 15, 2022

3460 - BLACKHOLES - a lonely blackhole discovered?

  -  3460  -  BLACKHOLES  -   a lonely blackhole discovered?   Now, astronomers have officially found another elusive object that has long been theorized but has never directly detected, a rogue blackhole.


-------------  3460  -  BLACKHOLES  -   a lonely blackhole discovered? 

-  We tend to think of blackholes as only those giant ones at the center of giant galaxies.  But, blackholes can come in all sixes if they are heavy enough, that is massive enough.  They start at about 150% the mass of our Sun.

-

-  The first Rogue Black Hole has been discovered just 5,000 Light-Years away.  Rogue refers to being lone outside of  galaxy.   Astronomers have been using the technique to detect everything from rogue planets to the most distant star ever seen.

-

-  Astronomers gathered data that all started back in 2011, when a star about 20,000 light-years away brightened suddenly.  Scientists were looking for just such an event and had found several before but needed more data to be sure of what they were actually seeing.

-

-  “Microlensing” leaves two tell-tale signs.  The object in the background of a microlensing event would grow significantly bright, as was seen with this star in 2011. In addition, telescopes would see the star shift ever so slightly as the massive lensing object passed in front of it.

-

-   Hubble observed the star a few weeks after its original brightening. They then checked back in with it periodically over the course of the next six years.  In that time frame, they also collected positional data, hoping to use a technique called astrometry to detect slight movements that would indicate the star was subject to a microlensing object between itself and Hubble.  

-

-  A combination of warping and amplification of the star’s light is exactly what Hubble saw.  But even that wasn’t conclusive enough to prove that the heavy object in front of the star was a blackhole.  

-

-  The duration of the lensing effect must last long enough to suggest a particularly deep gravity well.  The original event in 2011 lasted 300 days, enough to point to a blackhole that weighs approximately 7.1 times that of the sun.

-

-  With that weight estimate, scientists were also able to estimate how fast the blackhole was moving and came up with around 45 kilometers per second which is much faster than the stars surrounding it in that area of the Milky Way. 

-

-   Such a speed differential also points to a potential source of the blackhole itself,  an explosion from a supermassive star probably both created the blackhole and kicked it on its way.  The event happened around 100 million years ago, but it is hard to tell as there is no clear, traceable path to where the blackhole came from.

-

-  Even without that clear, traceable path, scientists have now definitively found something they have long sought, and they won’t be alone in doing so.  Several all-sky surveys are popping up soon that will help scientists consistently scan the skies for events like that in June 2011, and they will most likely find plenty more. 

-

-  Any of these hard-to-see masses of gravity might prove a threat to Earth, but the more we leverage new techniques like microlensing, the more likely we are to find any that eventually might be.  Stay tuned there is much more to learn before it is too late.

-

-

February 13, 2022     BLACKHOLES  -   a lonely blackhole discovered?       3460                                                                                                                                               

----------------------------------------------------------------------------------------

-----  Comments appreciated and Pass it on to whomever is interested. ---

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com -----  

--  email feedback, corrections, request for copies or Index of all reviews 

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

-----------------------------  Tuesday, February 15, 2022  ---------------------------






No comments:

Post a Comment