Hello Space Fans and welcome to another edition of Space Fan News
This week, astronomers using NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and
the European Space Agency's XMM-Newton space telescopes, have teamed up to measure definitively,
for the first time, the spin rate of a black hole with a mass 2 million times that of our
sun.
The supermassive black hole lies at the heart of a galaxy called NGC 1365, and it is spinning
almost as fast as Einstein's theory of gravity will allow.
The spin of the black hole was measured by looking at X-ray emissions from iron ions
trapped in the accretion disk of the black hole.
As most of you already know, accretion disks consist of anything and everything the black
hole has collected: gas, dust, stars, rogue planets - anything that's unfortunate enough
to get too close - and all that material is spinning around the event horizon.
What doesn't collect in the accretion disk is ejected outward at high speeds from the
poles in intense, high energy jets which are extremely bright in X-rays.
Collectively all this very active stuff swirling around in accretion disks and jetting out
into space is known as an active galactic nucleus and the presence of those jets mean
the black hole is feeding.
But the accretion disk itself doesn't generate x-rays, it's too cool for that.
Instead, what instruments onboard NuSTAR and XMM-Newton are looking at is reflected X-rays
off of the disk generated from the high energy jets.
So to get a good measurement of the black hole's spin, astronomers want to look at particle
motion as close to the black hole as they can get.
Those particles are the ones most closely bound to the actual black hole, revealing
it's spin rate.
By measuring the reflected X-ray emissions from Iron ions super close to the event horizon,
we can get direct information about how fast the black hole is spinning.
This information is in the form of redshift.
As the inner accretion disk rotates it is still emitting X-rays and is redshifted as
it does.
This redshift is directly related to the spin speed.
But wait a minute, it's not that easy.
There are two explanations for what could be causing the redshift of the Iron ions as
they rotate.
Remember that relativity taught us that space and time are warped by gravity and nowhere
is that effect more extreme than right next to a 2 million solar mass black hole.
One theory says that the X-rays are redshifted by relativistic effects near the black holes
surface.
So that's one reason.
The other was that obscuring clouds lying near the black hole were making the iron line
appear artificially distorted.
If this model were correct, then all bets are off, this data could not be used to measure
black hole spin.
Here's a chart of the two theories and what you'd expect to see in each case.
The top part is what we'd see if relativity were the cause, we'd see a distortion in the
iron feature, indicated by that spread out hump on the right side of the graph.
If there was a cloud in the way messing things up, we'd see the bottom graph.
See?
No iron feature distortion.
So what's the answer?
NuSTAR and XMM-Newton observations confirmed the relativistic theory.
The iron ions going around the event horizon of the black hole were being redshifted by
the intense gravity that warped space and time around the black hole.
That's not to say there weren't clouds though, astronomers know that there are some in the
area because they see them periodically in lower energy x-rays.
But NuSTAR allows astronomers to see the highest energy x-rays every seen, they aren't affected
by the clouds.
So there you have it folks, the theory of relativity is once again reinforced by observations
of one of the most extreme environments in the universe: black holes.
And using relativity, we can directly measure and determine the speed of a black hole's
spin.
So how fast is this one spinning?
84 percent of it's theoretical maximum.
This is one of the fastest spinning black holes ever detected.
And Measuring the spin of a supermassive black hole is fundamental to understanding its past
history and that of its host galaxy.
Next, astronomers using ESO's Very Large Telescope have made what might be the first direct observation
of a forming planet still embedded in a thick cloud of gas and dust.
Astronomers pointed the VLT at the thick disk of gas and dust that surrounds the young star
HD 100546, a relatively close star located 335 light-years from Earth.
What they found surprised them.
There appears to be a planet still in the process of forming and embedded in the disk
of material that surrounds the young star.
If this does turn out to be a planet, it would be a gas giant about the size of Jupiter.
The observations were made using a special coronagraph in an adaptive optics instrument
in the VLT, which operates at near-infrared wavelengths and suppresses the bright light
coming from the star at the location of the protoplanet candidate.
A protoplanet is just a planet that's not done yet.
A bun in the oven as it were.
It was observed as a faint blob located in the circumstellar disk in the outer reaches
of the system.
Astronomers have already suspected there's a planet around HD 100546 - a gas giant about
six astronomical units away from the star, but this one is farther out, about 10 times
farther out at sixty AU.
Although a protoplanet is the best explanation for what they're seeing, they aren't totally
sure.
It's possible that what they saw was from a distant background source not related to
the system.
It could also be that it might not be a protoplanet, but a fully formed planet which was ejected
from its original orbit closer to the star.
Obviously follow up observations are needed, and something tells me we're going to get
'em.
Finally, I wanted to let you guys know that next week, I'll be downtown.
Downtown Austin texas, that is.
At SXSW.
I'll be tweeting, blogging, hanging out and videoing as much as I can while I'm there
so stay tuned for that.
I want to hold an open realtime space fan hangout open to anyone who wants to join.
This could either be a really great idea or it could backfire, but I thought I'd give
it a try.
It also depends on whether I have enough bandwidth out there to do this.
Either way, I'll be posting something every day.
NASA will have a big presence there.
The full-sized JWST model will be there and so will lots of NASA dignitaries.
My goal is to try to bring as much of that experience to you as I can.
And if you're in the Austin Texas area, the NASA part of this is free, you can just stop
by and watch the talks and demonstrations and all the other cool stuff that's going
on.
I'd also love a chance to meet you, so make sure to look me up.
Please follow all my social stuff to keep informed of dates and time and all that stuff.
I'll also be doing next week's Space Fan News from there.
Well, that's it for this week Space Fans.
Thank you for watching and as always, Keep Looking Up!