Space Fan News #55: New Class of Black Hole Discovered; Echoes of the Past; Halo Around our Galaxy

Uploaded by tdarnell on 17.02.2012

Hello Space Fans and welcome to another edition of Space Fan News.
First up, researchers using the great and venerable Hubble Space Telescope have discovered
the first intermediate-sized black hole, so now we have THREE classes of black holes.
Remember before I said black holes came in two basic flavors: small, stellar-sized ones
that kinda roam around inside of a galaxy devouring whatever comes near them. These
black holes are the ones formed from the deaths of massive stars and are around 3 to a dozen
or so times the mass of the sun.
The other kind are supermassive black holes. These are the enormous black holes lying at
the centers of galaxies ranging from hundreds of millions to billions of times larger than
the Sun.
Now it seems there's a third class: intermediate-sized ones that falls in between these two.
So earlier this week, astronomers at the Center for Astrophysics in Harvard, along with NASA
announced the discovery of a black hole 20,000 times larger than the Sun.
No one has ever seen one this size before.
They are calling it Hyper-Luminous X-ray source 1, or HLX-1 and it sits on the edge of the
galaxy ESO 243-49, which is 290 million light-years from Earth.
The black hole is sitting in a cluster of young, blue stars orbiting around it. The
presence of the star cluster suggests that MAYBE this black hole is not a native to this
galaxy, instead it could have once been at the core of some dwarf galaxy that collided
with this one long ago, disintegrating the dwarf and leaving behind its remnants in this
larger galaxy.
The team observed HLX-1 simultaneously with NASA's Swift observatory in X-rays and Hubble
in near-infrared, optical, and ultraviolet wavelengths. The intensity and color of the
light shows the cluster of young stars, 250 light-years across, circling the black hole.
Hubble can't resolve the stars because the it's too far away (but JWST will).
Once again, Hubble shows its quality.
So let's see.... Discover a new class of black holes? Check.
Next, astronomers working at the Space Telescope Science Institute announced a finding today
that I didn't even know was possible. Astronomers are observing an event that had already been
seen on Earth. We've seen it once already, and now we're seeing it again.
I know, how weird is that? Apparently, about 170 years ago, there was a spectacular outburst
from the double-star system Eta Carinae, which we know is very unstable. Astronomers saw
this thing back in 1837 and was observed through 1858 and they called it "The Great Eruption".
Obviously, back then astronomers didn't have the kinds of telescopes we have today, so
the observations weren't as accurate and there weren't any cameras to record the event so
everything we know about it comes from eyewitness accounts.
But it looks like we're getting a second chance to record it.
Armin Rest and others at the Institute are using telescopes to record an echo of the
event that is arriving only now.
See, when the outburst occurred, the light heading toward us arrived 170 years ago and
we already saw that. But the light that went in the other direction - the direction opposite
the Earth - was reflected by distant gas clouds back towards us. That reflected light is only
just now getting to us, and we're recording it now.
I'm sorry, but that we can do this at all is absolutely just like downtown.
Eta Carinae is one of the largest and brightest star systems in the Milky Way and it's located
some 7,500 light years from us. Now while it's known for having lots of outbursts, the
Great Eruption was the brightest and most energetic ever recorded. During the 20-year
period of the outburst, Eta Carinae shed some 20 solar masses and became the second brightest
star in the sky while it was happening.
Some of the outflow formed these twin giant lobes you see here, and using spectroscopic
observations, they are able to determine that the ejected material is traveling at 700,000
km per hour, which matches predictions.
So this stuff is still streaming over us and they are rapidly taking images and spectra
to learn all they can that couldn't be learned 170 year ago.
I can't go over all the things they are learning by watching this echo, so I highly encourage
you to go to the press release and read the details, you won't be disappointed.
Finally, the Planck Space Telescope has detected an enormous haze over our galaxy.
As you should already know if you watch very many of these, Planck is designed to measure
microwaves and specifically the remnants of the big bang only visible in the cosmic microwave
background. A cool side effect of making the CMB maps though is that it has also given
us the most detailed microwave map of our galaxy ever assembled.
Using recent images, and carefully removing the microwaves from the foreground of the
Milky Way, astronomers found this huge galactic haze - a mysterious diffuse emission from
the central portion of our galaxy.
The tricky part was removing all the foreground emission from the maps, which are mostly produced
by free electrons and dust in the interstellar medium. After carefully doing that, they saw
No one knows for sure where it came from, but the type of light emitted is the same
as that emitted by electrons as they are accelerated through magnetic fields, something called
synchrotron radiation.
A weird thing about the radiation from the halo though, is that it's not the same as
synchrotron radiation seen elsewhere in the galaxy, so they're trying to figure out why.
Another thing Planck can see very well are molecular clouds, which are dense and compact
regions throughout the galaxy where gas and dust clump together. The vast majority of
gas in these clouds consists of molecular hydrogen (H2), and it is in these cold regions
that stars are born.
Here is where most of the stars in our galaxy will come from.
Well, that's it
for this week Space Fans, thank you for watching, and as always, Keep Looking Up!