Back in Time
The further we look into space, the further back in time we see. This simple statement is very counterintuitive for...
Tag: milky way
Universe Radio on Repeat
Looking at the universe in radio waves is a fascinating sight. For one, the radio sky is very weak; If you placed your cellphone on the Moon facing back at Earth, it would be brighter than all other radio sources in the entire sky by a factor of a million. But as with every other part of the electromagnetic spectrum, it has scientific value in studying the sky. Over the past decade, astronomers have been identifying several Fast Radio Bursts (FRB), short bursts of radio waves from different places in the universe that last for a few short seconds. These are...
The Big Spider
On the outskirts of the Milky Way galaxy, its two major satellites can be seen, the large and small clouds of Magellan. Both considered irregular galaxies, they are more like swarms of stars, similar to gnats here on Earth. But even though they lack structure, they are still alive. The large magellanic cloud contains the single largest active star forming region in the entire local group of galaxies. This is the Tarantula Nebula. In the core of the tarantula, huge supernova shockwaves blast gas and dust, triggering star formation while forming dense filaments away from the center. Along the entire...
Still More Hidden Galaxies
I’ve covered a few ‘hidden galaxy’ stories lately, from the ultra high resolution see-through of Andromeda, to dark dust in front of M81 and M82. Now, hundreds of new hidden galaxies have been revealed by a team of astronomers who are looking straight through the Milky Way for the first time ever, shedding light on the structure of new galaxy clusters and the enigmatic pull of the ‘great attractor.’ The Earth is not stationary in space. It orbits the Sun, which in turn orbits the Milky Way galaxy, which then moves through the Universe as part of a galaxy cluster. ...
Formation of Titans
Big stars tend to stick together. They all require incredibly dense regions in which to form, but once they do, they do a great job of blowing away and ionizing any other gas and dust in the vicinity. This is why nebulas in distant galaxies are great tracers of massive star formation. The bigger and hotter the star, the more UV light it produces, the more it ionized a gas cloud, the more we see gorgeous nebula. So it’s no surprise that when I look at the nebula below, I can guess that the central stars are huge, outweighing our...
Gamma Rays Point to Pulsars, Not Dark Matter
Gamma rays are the most powerful form of electromagnetic radiation in the universe. With wavelengths as small at atoms, they usually result from the most powerful interactions known, such as the collision of two particles, or the release of energy from the accretion disk of a black hole. But there is another potential source of gamma rays that has not yet been confirmed: Dark Matter. The leading candidate for dark matter is the theorized Weakly Interacting Massive Particle (WIMP), though it is not as wimpy as its namesake suggests, making up 5 times as much mass as the visible matter...
More Stuff to Block Galaxies
A few days ago I wrote about a galaxy that was tough to see because of Milky Way field stars. But our galaxy is far more than just a bunch of stars smattered about. There is also a huge amount of gas and dust with varying temperatures. Some of the hotter and more illuminated gas and dust are what make nebulae so lovely in space. But the cold gas and dark dust that is just out floating in the cold interstellar medium? That stuff gets in the way. A normal image of interacting galaxies M81 and M82 would try to hide the...
Galactic Hide and Seek
Remember the big picture of Andromeda that showed 100 Million stars? That image resulted in a ton of new galaxy discoveries. Most of these new galaxies were once hidden beyond the Andromeda galaxy, but with the super high resolution image, astronomers and the public were able to look straight through and see far more distant objects. Most images of galaxies have what we call ‘field stars’ in them. These are some of the 400 Billion stars of the Milky Way that are far closer than the galaxy we are imaging. For this reason, galaxy images tend to look very cluttered...
A Ticking Time Bomb
There are many types of objects in space that just can’t be seen with visible light, and many more that have very different features when observed across the electromagnetic spectrum. A prime example of the former is a molecular cloud. Cold, incredibly huge, and full of low density Hydrogen, these clouds are the raw material for star forming galaxies. If stars begin to form within them, they can be seen as gorgeous nebulae, but when alone in the darkness of space we need to look for the dim signature of radio waves they emit. The Smith cloud, named after it’s...
Dark Matter in a Galaxy Cluster
We know that galaxies like our Milky Way are far more massive than we can see. The dark matter in the Milky Way makes up 90% of it’s total mass. Another way of saying this is the Mass to Light ratio, comparing the total mass inferred by the rotation speed of the galaxy to the total mass of stars in the galaxy. This ratio, M/L, for the Milky Way, is about 10. But for a galaxy cluster, the M/L ratio is more like 100. Galaxy clusters are not just dense collections of stars and massive galaxies, they are also immense...