Tip:
Highlight text to annotate it
X
Hello Space Fans and welcome to another edition of Space Fan News.
Big News Everyone!
Or I should say, Big *** News Everyone!
By now you've probably all heard the news released on Monday that astronomers looking
for gravity waves in the Cosmic Microwave Background have actually found some and it
is a direct observation of a period in our universe's history called inflation.
If these results are confirmed, this would be the biggest news concerning our place in
the universe next to finding life on another planet, and according to Sean Carroll of Cal
Tech, the biggest thing since Dark Energy.
Why? Because it gives us experimental evidence that the period after the Big *** known as
Inflation occurred. We can see it, right there in the CMB.
Directly.
Inflation is the time after the Big *** when the universe expanded very quickly, exponentially
in fact. See that part after the Big *** where the universe gets really big really
fast? That's inflation.
The universe went through a phase of accelerated expansion for some reason or other.
Nobody knows why this happened but there are many models explaining how it could happen
and what it would look like if it did, and this week's announcement found a key predicted
feature that should exist if inflation occurred.
To understand this a little better, you need to realize that the basic effect of the inflationary
era in our universe was to smooth things out, stuff like density perturbations and spatial
curvature, stuff like that. These blue and red areas in this image of the CMB show the
perturbations, some parts are slightly hotter or cooler than others.
But inflation doesn't completely smooth things out. Quantum mechanics says we can't completely
do that, there will always be an irreducible minimum amount of jiggle that will survive.
To be honest, Inflation makes my head hurt, but suffice it to say that the entire point
of inflation is to make the initial conditions of our observable universe seem more natural
and to get it to do that it needs to start in a very particular kind of state which raises
problems among some cosmologists.
But it makes predictions which have come true: the universe is roughly the same everywhere
we look and the curvature of space is pretty small. And it also says that the perturbations
on top of this basic smoothness are where we'll find clues about the Inflationary Era.
There are two types of perturbations astronomers expect to see based on the quantum fields
that fluctuated during Inflation: the inflation field itself and the gravitational field.
Nobody knows what the Inflation Field is, they just call it 'The Inflation' and it's
the inflation that eventually converts into all the matter and radiation in the cosmos
so finding out what that is is also a big deal, but that hasn't happened yet.
But the gravity field we know about. First, we know the waves are there because gravity
exists and it's massless. Second there is a way to separate the gravity waves from the
density changes in the CMB by looking for polarization.
Polarization describes the direction of vibration of a wave. And right now all I have time to
tell you is they can wiggle this way or that way and depending on the direction, they are
given names.
So this week, astronomers using The Background Imaging of Cosmic Extragalactic Polarization
2 experiment (BICEP2) at the South Pole found a pattern called primordial B-mode polarization
in the light of the CMB, just as had been predicted by inflation theory.
There is a chance that this finding could be wrong but a lot of cosmologists are pretty
excited about the result and seem confident in the analysis done by the BICEP2 team.
I can go on forever about this topic, but I only have a few minutes, so please join
Scott Lewis and I this week for Space Fan News Live and we'll go into way more detail
about this finding.
Next, astronomers using ESO's Very Large Telescope Interferometer have discovered that a hyper
giant star - one of the ten largest stars ever found and is the largest yellow star
ever seen - is part of a double star system that is very strange.
The hyper giant, known as HR 5171 A is 1,300 times the diameter and one million times brighter
than the Sun. Using observations spanning over 60 years, astronomers found a second
star in orbit around it that is so close that it actually touches the main star.
I told you about hyper giants before in the video on VY Canis Majoris, the largest star
ever discovered, but unlike VY Canis Majoris, this star is yellow which is very rare among
hypergiants - we only know of about a dozen or so in our galaxy.
Yellow hypergiants are among the biggest and brightest stars known and are at a stage of
their lives when they are unstable and changing rapidly. Due to this instability, they also
expel material outwards, forming a large, extended atmosphere around the star.
To find the second star in the binary, astronomers made use of a technique called interferometry
to combine the light collected from multiple individual telescopes, effectively creating
a giant telescope up to 140 meters in size.
The new results prompted the team to thoroughly investigate older observations of the star
spanning more than sixty years, to see how it had behaved in the past.
They've found that it has gotten bigger over the last 40 years, cooling as it grows, and
its evolution has now been caught in action. Only a few stars are caught in this very brief
phase, where they undergo a dramatic change in temperature as they rapidly evolve.
By analyzing data on the star’s varying brightness and using observations from other
observatories, the astronomers confirmed the object to be an eclipsing binary system where
the smaller component passes in front of and behind the larger one as it orbits.
Here it is orbited by its companion star every 1300 days. The smaller companion is only slightly
hotter than HR 5171 A’s surface temperature of 5000 degrees Celsius.
This companion star is significant because it can influence the fate of HR 5171 A. For
example, it can strip off the outer layers which would have a direct effect on its evolution.
Now even though HR 5171 A is 12,000 light years away, if you live in the southern hemisphere
you can actually see it with your naked eye on a clear, dark night. It is in the Constellation
Centaurus with a visual magnitude of about 6.1 to 7.3, so by all means get out there
and check out the largest yellow hyper giant we've ever seen.
Finally, after searching hundreds of millions of objects across our sky, NASA's Wide-Field
Infrared Survey Explorer (WISE) has found no evidence of the hypothesized celestial
body in our solar system known as "Planet X."
Now, I'll be honest, I had no idea we were still looking for Planet X, but I guess we
were.
Planet X was this theorized, large celestial body that we couldn't see. Many thought it
might be a large gas giant in the outer solar system or a small, companion star.
But astronomers pouring over the catalogues created by WISE have found nothing directly
related to a specific body.
What they have found though, is several thousand new brown dwarf stars they hadn't seen before,
which would explain some of the reasons for the Planet X theory.
It turns out that brown dwarfs, which are otherwise very hard to see, are easy-peasy
to find using WISE.
By just concentrating on these objects beyond our solar system, they have found 3,524 stars
and brown dwarfs within 500 light years of our Sun.
These objects were completely overlooked before and despite the large number of new solar
neighbors found by WISE, "Planet X" did not show up.
Astronomers think there are even more stars out there left to find with WISE.
I guess we don't know our own sun's backyard as well as you might think.
Well, that's it for this week Space Fans, thank you for watching and as always, Keep
Looking Up!