Space Fan News #74: Dark Galaxies Found; Vampire Stars Eat Their O's; NASA's New Mars Mission

Uploaded by tdarnell on 24.08.2012

Hello Space Fans and welcome to another edition of Space Fan News.
This week, astronomers using ESO's Very Large Telescope announced back in July…
Yes I know it's August, but gimme a break, I've been on vacation and August is a slow
month for astronomical discoveries so I gotta go back to July to find the good stuff.
Astronomers using ESO's Very Large Telescope have direct observational evidence of dark
Dark galaxies are really strange things, they are predicted by prevailing theories of galaxy
formation, but have never been observed.
Until now.
They existed in the very early universe and consist primarily of gas - they contain almost
no stars.
And because they don't have many stars, they don't shine very bright, making them extremely
difficult to see through a telescope. They don't emit much light, hence dark.
Galaxies in the early universe were really inefficient at making stars, the gas in them
is still primarily very light neutral hydrogen and molecular hydrogen and it takes a while
for the dark matter in the area to clump that light stuff into stars.
In this research, we're talking about galaxies with a redshift of about z=2.4, putting them
at an epoch of about 10 - 11 billion years ago or when the universe was about 2-3 billion
years old.
Finding these dark galaxies has always been problematic. Since they don't have many stars
and they are mostly just gas, the best way to find them is by shining a light on them.
An analogy would be shining a searchlight up into a dark night sky on a cumulus cloud.
The cloud isn't emitting anything, but will reflect a light shown on it.
But how do you do that with a distant galaxy?
Good question. The answer is you need a bright light bulb in the distant early universe that
will shine a light on them for you.
And guess what? Astronomers found one. In fact they found the brightest flashlight in
the universe right nearby.
There is a bright quasar known as HE 0109-3518 in the constellation Sculptor and taking advantage
of the huge light collecting area of the VLT, astronomers searched the area for the fluorescent
glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from
the nearby, and very bright, quasar.
The light from the quasar lit up the dark galaxies like a white t-shirt in a night club
full of black lights.
Using this technique, the team detected almost 100 gaseous objects which lie within a few
million light-years of the quasar. They sifted through those 100 and after excluding those
objects where the emission might be powered by internal star-formation in the galaxies,
they were left with 12.
The remaining 12 objects are the most convincing observations of dark galaxies in the early
Universe to date.
So here we go again, theory predicted something very hard to see should be there.
We looked real hard using really clever techniques and ginormous telescopes.
And there they were, right where they should be.
Just like downtown.
Next, sticking with ESO for the time being, astronomers - again using the Very Large Telescope
(that sure is a handy little thing) - have discovered that most bright, high mass stars
have a companion.
Until now, astronomers have always thought that these giant stars were loners, that they
were out in galaxies all by themselves, Well, it turns out this isn't true, they aren't
loners. These stars in question are called O-type stars, and are 15 times the mass of
our Sun and about a million times brighter.
These guys studied a sample of 71 O-type single stars as well as stars in pairs in six nearby
young star clusters in the Milky Way.
By analysing the light coming from these stars in great detail, the team discovered that
75% of all O-type stars exist inside binary systems, a higher proportion than previously
What's more, these binaries are very strange, the stars are interacting with each other.
Many of them are so close that one star is literally sucking the life out of the other.
Those stars are called, regrettably, vampire stars, and the percentage of binaries acting
this way is much higher than anyone thought.
What makes this so significant is that this has profound implications for our understanding
of galaxy evolution. As you can imagine, O-type stars - because they are so big and bright
and during their lives, they spew out enormous quantities of radiation, have outbursts that
induce bow shocks, have very powerful stellar winds, and explode when they die, have a disproportionate
effect on their immediate surroundings compared to quiet stars like the Sun.
Examples of some of the ways they affect galaxies are: the winds and shocks coming from these
stars can trigger and stop star formation, their radiation powers the glow of bright
nebulae, their supernovae enrich galaxies with the heavy elements crucial for life,
and they are associated with gamma-ray bursts, which are among the most energetic outbursts
in the universe and - as anyone who's played MyStar can attest - can ruin any life that
may be on any nearby planets.
All of this means that O-type stars heavily influence the mechanisms that drive the evolution
of galaxies.
Here's what I mean, take vampire stars, the smaller, lower-mass star is getting stronger
and brighter as it sucks the fresh hydrogen from its companion. Its mass will increase
substantially and it will outlive its companion, surviving much longer than a single star of
the same mass would.
The victim star, meanwhile, is stripped of its envelope before it has a chance to become
a luminous red super giant. Instead, its hot, blue core is exposed. This means that we aren't
getting an accurate picture, the stellar population of a distant galaxy may appear to be much
younger than it really is.
Knowing the true proportion of interacting high-mass binary stars is therefore crucial
to correctly understand how galaxies are evolving.
So much for vampires not being out in the Sun…
Finally, if you haven't had enough of Curiosity yet, then you're in luck - there's more Mars
scheduled in the future. NASA has decided what it's next mission to Mars will be. Earlier
this week, they announced that InSight, a new Discovery-class mission will probe Mars
at new depths by looking into the deep interior of the planet for the first time.
InSight is going to drill beneath the red topsoil of Mars with something called the
HP3 or, Heat Flow and Physical Properties Package – one of the four instruments it
will carry.
I'm going to give you a quote here, because I thought this was hilarious: Made by the
German Aerospace Center, or DLR, HP3 will get below Mars' skin by literally pounding
it into submission with a 14-inch (35-centimeter), hollowed-out, electromechanically-festooned
stake called the Tractor Mole.
Ah, to have an electromechanically-festooned stake…
If I had one, I would most definitely call it The Tractor Mole.
Anyway, the mission is slated to launch in 2016, I'll keep you posted.
Well, that's it for this week Space Fans, thank you for watching, and as always, Keep
Looking Up!