Hello Space Fans and welcome to another edition
of Space Fan News.
Remember back in January when I was covering
the AAS and talked about a study done at the
European Southern Observatory where they estimated
the number of planets in our Milky Way to
be about 1.6 times as many stars as it had?
It said that our galaxy contains, on average,
160 billion planets.
Remember that?
Well, what if there were really about 50,000
times more planets than that floating around?
A new study released by researchers at the
Kavli Institute for Particle Astrophysics
and Cosmology (KIPAC), which is a joint institute
of Stanford University and the SLAC National
Accelerator Laboratory, have estimated that
there may be, in addition to the 1.6 planets
per star already estimated to be in orbit
around stars in the galaxy, that there are
an additional 100,000 planets PER STAR swarming
around our galaxy.
All these extra planets would be something
called nomad planets, which I'll get to in
just a minute.
So listen carefully: these guys are estimating
that there are 100,000 times 100 billion stars
in our galaxy.
And that's just the nomad planets, it doesn't
count the planets around stars.
In case you don't want to do the math, that's
a 1 with 16 zeroes after it, or 10 quadrillion
nomad planets in the Milky Way.
In addition to the 160 billion planets in
orbit around stars!
Whoa!
So... to paraphrase Roy Scheider's character
in Jaws: we're gonna need a bigger galaxy.
So what's a nomad planet?
A nomad planet is a planet with no parent
star, they're just wandering around the galaxy
in interstellar space.
They might have an atmosphere, they might
not, and these researchers came to this humongous
number by taking into account the known gravitational
pull of the Milky Way galaxy, the amount of
matter available to make nomad planets (that
wasn't already making up a star or a planet)
and how that matter might divide itself up
into objects ranging from the size of Pluto
to larger than Jupiter.
Now as you can imagine, this was far from
an easy task, considering no one is quite
sure how these things form in the first place.
Some were probably ejected from solar systems,
but research indicates that not all of them
could have formed in that way.
If actual observations confirm this estimate,
then this new class of celestial objects will
affect what we think about planet formation
and could also change our understanding of
the origin and abundance of life.
How?
If any of these nomad planets are big enough
to have a thick atmosphere, then it's possible
that they could trap enough heat for bacterial
life to exist.
So, although nomad planets don't orbit any
star, it's possible that they could generate
heat through internal radioactive decay and
tectonic activity to keep little microbial
critters alive.
If they can do that, then as these nomad planets
drift between the stars, collisions between
them could scatter any bacterial passengers
they may have and seed life elsewhere, like
the early Earth for instance.
This could be one possible mechanism for life
to pollinate solar systems.
In order to find out for sure about any of
this, we need observations from better telescopes
than we have right now, and the next generation
of Big Survey telescopes are ideal for this.
In the coming years, we have the LSST project
(which stands for Large Scale Synoptic Survey)
and the space-based Wide Field Infrared Survey
Telescope which will hopefully settle this
for us.
Can you imagine?
Ten quadrillion planets in our galaxy alone!
The numbers just keep getting more mind boggling..
Next Astronomers observed what appeared to
be a clump of dark matter left behind during
a bizarre wreck between massive clusters of
galaxies and what they've seen doesn't make
any sense.
This is the Abell 520 Cluster, also called
the Train Wreck Cluster.
This is the scene of a massive collision of
at least two, but possibly three clusters
containing several hundred galaxies.
This cluster lies at the apex of around three
enormous filaments of the universe where galaxies
are guided along huge tendrils of spacetime
and are smashed into each other where those
tendrils meet.
It is one of the most dynamic regions of the
known universe.
But looking at the aftermath of some of these
collisions leaves behind some confusing evidence.
As the galaxies past each other, the dark
matter that collected into a sort of "dark
core" contained far fewer galaxies than would
be expected if the dark matter and galaxies
had hung together.
Apparently, most of the galaxies involved
in the collision left the scene, which is
strange because most theories about dark matter
say that the galaxies should have been held
closer to each other, closer to the dark matter
blob.
But that's not what they see, not enough galaxies
stayed behind.
It's too empty here and this has astronomers
second-guessing what they think they know
about dark matter.
This collision was originally observed in
2007, and astronomers shrugged it off as bad
data, but when the Hubble Space Telescope
looked at it in 2008, they still saw that
the dark matter and galaxies parted ways in
the cluster, which is some 2.4 billion light-years
away.
Now, astronomers are left with the challenge
of trying to explain what happened.
They are proposing many explanations for this,
none of them are very comforting.
One scenario, which would have huge implications,
is that some dark matter may be what astronomers
call "sticky."
Normal matter is sticky, when it interacts
with other normal matter, like in a collision,
or a gravitational encounter, it slows down.
Dark matter, it is thought, doesn't do this,
instead the blobs are thought to pass through
each other during an encounter without slowing
down.
But what if some dark matter interacts with
itself and stays behind during an encounter?
That might explain what is seen here.
Another possible explanation for the discrepancy
is that Abell 520 has resulted from something
more complicated.
Because this is the apex of three giant streams
of galaxies in the universe, it may have formed
from a collision between three galaxy clusters,
instead of just two colliding systems seen
in many other observations.
A third possibility is that the core actually
does have many galaxies, but they are too
dim to be seen, even by Hubble.
But for those galaxies to be missed, they
would have to have dramatically fewer stars
than other normal galaxies.
So now what they're gonna do is armed with
this Hubble data, the group will try to create
a computer simulation to reconstruct the collision
and see if it yields some answers to the dark
matter's weird behavior.
Well, that's it for this week Space Fans.
Thank you for watching, and as always, Keep
Looking Up!
