Seeding The Supermassive

In the early Universe, things were quite different.  The first stars were much more massive than stars today, and contained mostly Hydrogen.  Astronomers have good ideas about how they formed, but other objects from around this time, namely black holes, are much tougher to account for.  Early black holes were huge, with no explanation for how they grew so large.  “Early” means “first Billion years after the Big Bang,” but even in that time, it’s hard to determine how observed black holes could grow as large as 100,000 solar masses. I say 100,000 solar masses, because that is the mass of two ‘seed’ black holes, discovered...

Black Holes ARE Dark Matter?

Dark matter could be almost anything.  With little data other than how much total dark matter mass exists, we can’t decode much about what individual chunks of dark matter might be made of.  I’ve talked before about Massive Compact Halo Objects (MACHOs) and Weakly Interacting Massive Particles (WIMPs), but these are just two possibilities.  Other theorists have talked about Modified Newtonian Gravity (MNG), where gravity may work differently on the grand scale than it does on our small Earth scales.  Or perhaps it’s something I haven’t seen before.  Maybe what we call dark matter is just a large population of ancient black holes....

Heavy Metal

Where do the heavy elements on the periodic table come from?  The general answer is from what’s called the r-process of stellar nucleosynthesis.   This translates to ‘rapid neutron capture’ being the method by which most of the elements heavier than Iron are formed on the periodic table.  This process requires immense energy and was originally thought to only occur within core-collapse supernova explosions. “Understanding how heavy, r-process elements are formed is one of hardest problems in nuclear physics,” said Anna Frebel, assistant professor in the Department of Physics at the Massachusetts Institute of Technology (MIT) and also a member of...

Falcon Flight to the Galaxy

In the APOD photo from May 14th, it is easy to imagine the rocket launching far away into the galactic disk.  Sadly the rocket can’t traverse the thousands of light years to reach the distant stars, and is restricted to orbiting the Earth. Another beautiful part of this image is the technique involved in producing it.  It required combining two exposures. The first, with low sensitivity to capture the orange rocket trail of the Falcon 9.  The second with high sensitivity and a longer exposure time to capture the faint light of the Milky Way galaxy beyond.  The result is...

A Lonely Universe?

Life in the universe is a fascinating topic.  The simplest question: Are we alone? It breeds so many deeper and more profound scientific questions, like “How many habitable planets are there?” “How likely is life to develop on any given planet?” and “How long can a civilization survive?” We can’t answer them definitively, but we can narrow it down. The Drake equation, shown above, was first developed by Frank Drake, the head of the Search for Extraterrestrial Intelligence (SETI), in 1961.  He took the question of are we alone and made it quantifiable, in a probabilistic way.  It lets us...

Stellar Snowball

The closest star to the Earth, aside from the Sun, is Proxima Centauri, a small red dwarf star that is part of the Alpha Centauri system, roughly 4 light years away.  If you don’t know light years, the distance is a staggering 37,800,000,000,000 Km.  Beyond that our stellar neighbourhood fills in as you move 20 light years in any direction, and by 100 light years, there are dozens of stars around us.  This gives a stellar density of about 0.14 stars per cubic parsec (a parsec is about 3.26 light years), pretty normal in terms of the number of stars in a given...

Blast From The Past

A supernova is the death blast of a giant star, far larger than our Sun.  Massive stars go out with a bang, outshining entire galaxies, allowing us to see them across the universe.  A supernova observed in 2013 occurred in a distant galaxy and took over 30 Million years to reach Earth, where the timing was perfect for us to observe and study it.  And now that it’s been studied, the explosion was truly the death of a giant. The supernova, named 2013 ej, was discovered in June 2013 in the galaxy M74 in the constellation Pisces.  It was the closest supernova...

Dark Matter is Complicated

The fact that we have found gravitational waves tells us that we have come a long way in terms of science and technology.  We detected a perturbation in the fabric of space-time that was one one-thousandth the diameter of a proton.  It’s insane to think about that level of precision.  And yet we still can’t find Dark Matter, the stuff that is literally everywhere in the universe.  Is it our problem? Or is dark matter just on a whole different level? By now, we know that dark matter isn’t some clump of stuff sitting out there in space.  But that...

A Ring of Fire

A direct consequence of Einstein’s theory of general relativity, and an observational way to prove it, is gravitational lensing.  It requires a powerful gravitational source to work, such as a galaxy or cluster of galaxies.  It works in a similar way to a lens of glass, where rays of light are bent toward a single source, increasing the brightness.  In this case, instead of glass, the bending of the rays is due to the curvature of space. Light rays coming from the source would otherwise miss Earth, but instead are bent toward us when there is a massive object in front of it.  It’s...

Building the Supermassive

Black holes form when a massive star runs out of fuel.  Gravity causes the core to collapse down to an object so dense that light itself can not escape.  In the Milky Way galaxy, there are expected to be over 100 Million black holes, though of course we can’t see them.  The one we can see is the supermassive black hole Sag A*, lying deep within the core of the galaxy.  But how did Sag A* form? Was it from the merger of many smaller black holes?  Or is there some other process forming the most enigmatic objects in the...