Hello Space Fans and welcome to another edition of Space Fan News.
You know, it really amazes me the kinds of questions we can answer in astronomy these
days.
For example, how many active supermassive black holes are there in the universe?
Turns out we have an answer for that now, at least out to 10 billion light years. There
are about two and half million supermassive black holes in the universe within about 10
billion light years of us.
How do we know this?
The infrared baby, the infrared.
NASA's Wide-field Infrared Survey Explorer (WISE) telescope looked at the entire sky
in the IR - twice.
That's the entire sky, in the infrared, two times.
WISE stopped taking data in 2011 but of it has been released to the public and astronomers
have been pouring over it.
It turns out that WISE is a very efficient black hole finder. Most black holes are usually
found by looking for high energy jets in X-rays, but X-rays are easily scattered and hidden
behind dust clouds, so a lot of them are missed in those shorter wavelengths.
WISE doesn't suffer from that bias and can find ALL active black holes, even those shrouded
in dust, because the energy released from supermassive black holes heats up the dust,
making it glow in the IR, and is easily visible to WISE detectors.
So, pouring over the all sky survey made by WISE, astronomers have found two and a half
million actively feeding black holes at the centers of other galaxies out to 10 billion
light years.
Another discovery that's come out of this survey is astronomers have found some of the
brightest galaxies known.
These galaxies are more than 100 trillion times brighter than our Sun, very bright,
but they are also very dusty objects, so they are dim in the optical and appear only in
the longest wavelengths that WISE can see.
These galaxies also have supermassive black holes heating up the gas surrounding the galaxies,
making it visible to WISE.
But after searching the entire sky, WISE only found 1,000 possible candidates for these
galaxies and followup studies have confirmed 100 of them.
One thousand candidates across the entire universe makes these pretty rare objects,
there aren't many out there, but they have the very interesting property that their central
black hole may have formed before the bulk of the stars in the galaxy did, meaning that
these black holes at the centers of these objects were among the first to form in the
universe.
These observations also revealed that these extreme galaxies are more than twice as hot
as other infrared-bright galaxies and astronomers think that they may represent a rare phase
in the evolution of galaxies.
They are calling these things Dust Obscured Galaxies or DOGS.
And they are hot.
You know what's coming next don't you? Yep. They're hot DOGS.
OK, moving along quickly…
I'm glad I get to talk about ALMA, The Atacama Large Millimeter/submillimeter Array. This
is a massive array of antennas all linked together to look at the sky.
A total of 66 radio antennas are coordinated to look at various regions of the sky. Signals
captured by each one are combined to provide images that are equivalent to a telescope
14,000 meters in diameter.
This means ALMA can see very faint objects in radio wavelengths at a very high resolution.
Some of the things ALMA is good at doing is measuring the radius and rotations of stars,
studying protostellar collapses that creates new stars, studying the chemistry of dust
clouds around star systems, and looking at the hot DOG galaxies we talked about earlier.
ALMA came online in October of 2011 and is now starting to produce results.
At the end of August, astronomers announced that they had found the building blocks of
life in a gas cloud surrounding a young binary star.
Specifically, they found a simple form of sugar - glycolaldehyde - around IRAS 16293-2422,
a star about the size of the Sun and is about 400 light years away.
Now this stuff has been found in interstellar space before, but this is the first time it
has been found so close to a Sun-like star, and at distances comparable to that of Uranus
from the Sun in our Solar System.
These sugar molecules were also found to be falling in towards one of the stars in the
system, so not only are they in the right place to find their way onto a planet, they
are also going in the right direction.
This discovery shows that some of the chemical compounds needed for life existed in this
system at the time of planet formation and would never have been seen without the high
sensitivity of ALMA.
Finally, the Kepler Space Telescope has found it's first multi-planet system around a binary
star.
Now, don't confuse this with the discovery I talked about in SFN #32 where Kepler had
found a planet that orbited two stars. Remember, they were calling it Tatooine?
That was one planet around two stars, here there are two planets around two stars.
And one of them sits in the habitable zone.
The system is known as Kepler-47 located about 5,000 light years from Earth. the two stars
in the system are whipping around each other once over seven and a half days. One of the
stars is similar to our Sun while the other is a smaller star only one third the size
and 175 times fainter.
The inner planet, Kepler-47b, is three times larger than the Earth and orbits once every
49 days.
The outer planet, Kepler-47c, is about 4.5 times the size of the Earth — slightly larger
than Uranus — and orbits the stars every 303 days. This makes the outer planet the
longest-period transiting planet currently known.
And it's in the habitable zone. Liquid water could exist here if it was present.
The problem is though, Kepler-47c is a gas giant, so we'd have to look at any moons it
might have as a possible harbor for life.
Since these planets are relatively small, they don't make the stars wobble very much
so their masses couldn't be measured directly, but based on their size, the inner and outer
planets probably have masses of approximately 8 and 20 times that of the Earth, respectively.
Well, that's it for this week Space Fans, thank you for watching and, as always, Keep
Looking Up!
