Dark Matter Stars May Have Seeded Supermassive Black Holes

We're getting very theoretical here, considering we're not even sure what dark matter is. Anyway, in the early universe, when all the matter was squished together a lot more tightly than it is today, stars that formed were often a little different. Oh sure, they were made of hydrogen, but they also contained a bit of dark matter in the form of Weakly Interacting Massive Particles.

These dark matter stars would have looked a lot different than the stars we know today. For one, they were gigantic, spanning up to 10 AU across. They could be millions of times heavier than the sun, and billions of times as bright.

The existence of these stars could solve a big mystery of the early universe. Galaxies seemed to form around supermassive black holes, but where did these black holes come from. A gigantic star would collapse into a gigantic black hole. It's almost a little too obvious.

What Will Stars Look Like in the Distant Future?

I'm talking billions, trillions of years, maybe even more. It's a somewhat sobering reality that nearly all of the stars that will be born during the lifetime of the universe have already been made. Now, stars as we know them will continue being made for billions of years, far beyond the life of humanity. But in the far-flung future, different types of stars will begin to pop up, stars that haven't had enough time to develop yet. Here's a list of four of those hypothetical future stars:

This won't do you much good here.

1. Blue dwarf. They're simple enough, they're the final phase of evolution of red dwarfs, the smallest type of star. Instead of expanding into a red giant like the Sun will when it starts fusing helium, they'll get smaller and much hotter, turning blue. However, their ultimate fate will be the same, eventually turning into white dwarfs.

2. Black dwarf. Hey, speaking of white dwarfs, this is what will happen to those after billions of years and they've cooled off. To call it a star is a bit generous, a black dwarf will be a planet-sized lump of super-dense matter generating little, if any, light.

3. Frozen star. Here's where things start to get strange. Eventually, the universe will run low on hydrogen and helium, but stars of a sort will continue to form, fusing paltry scraps of hydrogen in among icy clouds. These stars would struggle to get past the melting point of water, and would resemble giant brown dwarfs rather than actual stars.

4. Iron star. Now we're into real hypothetical territory here. As the universe slowly expands to infinity, undergoing heat death, there will be a lot of iron floating around. Iron is both extremely stable and if you know your fusion, you'll know that once you start fusing iron, more energy is used to make the reaction than is put out. That's what causes supernovae. However, and providing protons don't decay, when a bunch of iron clumps together to form a body, quantum shenanigans will cause an ignition of sorts, splitting the atoms and forming an iron star.

The Universe's First Stars Have Been Discovered

These are some pretty old stars we're talking about here. Previously, the oldest stars we knew about formed 400 million years after the Big Bang, but it was suspected that stars formed much earlier than that. We just couldn't see them yet. Well, now we have. And they did form much earlier, coming into existence a mere 180 million years after the Big Bang.

Credit: N.R. Fuller, National Science Foundation

Finding these old stars took some doing. Until 500 million years post-Big Bang, the universe was filled with loose, heated hydrogen, which is very good at blocking light. So instead of looking for the stars themselves, astronomers have to look for their impact on the cosmic background radiation. This is no easy task, the radio signals astronomers were searching for were something like 10,000 times dimmer than normal radio noise. But you know what? They did it.

Besides that, there's something interesting going on with the signals. They're twice as bright as expected, meaning the radio background was stronger than expected, or the hydrogen filling the young universe was cooler. The second option is more likely, but what would be cooling down the hydrogen is a mystery. A likely contender is dark matter. If that's the case, this discovery may accidently have given us our best look at what dark matter actually is. And that's news worth mentioning.

The Case of the Missing Stars

It seems that globular clusters in the Fornax galaxy cluster are missing some stars. The population of these globular clusters is split equally between old stars and new stars. This does not fit in with current theories on the formation of those objects. Until now, scientists assumed that the stars in globular clusters all formed at the same time, and that most, if not all the stars would be old. Any new stars would form from ejected star material, but theories predicted that old stars should outnumber new stars considerably. Observationally, that isn't the case for Fornax.

It's actually not the case for the Milky Way's globular clusters, either. They have a similar star make-up, but scientists assumed that something caused the clusters to lose older stars. They can't make the same assumption for Fornax, because there's nowhere the stars could have gone where we couldn't detect them. They're just not there. So, it may take some serious rethinking to figure out how these globular clusters actually formed.

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The Most Important Science News You've Heard in the Last Five Minutes

I could spend this post talking about how half of all Earth's wildlife has died since 1960, everybody else certainly is.  It's a big number, but honestly?  Not that surprising.  I guess it's good to have a number on just how much of nature we've killed off, but it didn't take a genius to know it was a lot.  No, today, I'm going to talk about something much more important in the world of science: gigantic solar flares.

When I say gigantic, I mean it.  These flares, coming from DG Canum Venaticorum, a red dwarf binary system 60 light years away, are the biggest ever recorded.  It was about 10,000 times more powerful than our sun's meager flares, reaching a temperature of 360 million degrees.  The stars are young, only about 30 million years old, but the key to the flare was the rotational period of the flare star.  It orbits in about a day, while the Sun takes about a month.  Fast rotation means more magnetic  activity, which leads to more powerful solar flares.  That's how a piddling little red dwarf produced the most powe
rful solar flare ever.

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