Tag: astronomy

Reonization galaxy

For 100s of millions of years after the Big Bang, the entire universe was a thick soup of hydrogen atoms swimming in total blackness. So dense was this cosmic goulash that the first light from the first stars in existence couldn’t penetrate it — the hydrogen fog simply absorbed and scattered the starlight in circles, trapping the universe in a cosmic dark age as ever more stars, galaxies and black holes slowly smoldered to life. That all changed after 500 ma, when a grand cosmic makeover called the epoch of reionization began. As ancient galaxies grew ever larger and radiated more powerful energy, they began to burn away the cosmic fog that surrounded them by ionizing hydrogen atoms into a plasma of free protons and electrons. Suddenly, light could travel across the cosmos — first through “bubbles” of plasma surrounding large galaxies, then farther and farther as multiple bubbles began to expand and overlap. The galaxy group, named EGS77, dates to 680 ma after the Big Bang and appears to be surrounded by 3 overlapping bubbles of plasma — meaning these pioneering galaxies may have been caught in the act of reionizing their corner of the universe and bringing the cosmic dark ages to an end.

Dusty Stars

Are we seeing 6 V838 Monocerotises orbiting our galaxy’s central supermassive black hole? It’s certainly possible. The number we see fits, the idea that they are stars embedded in dense dust clouds fits, the dynamics fit, and we have an example of just such a beast. There was a recent burst of star formation in the galactic center ~4–6 ga ago, which very well could have been when these binaries were born.

dust clouds with stars embedded in them.

Hawking radiation

the hologram within a hologram gives the desired answer to the question of what happens to a 2D black hole’s information. Most experts assume that if the reasoning is correct, it should carry over to higher-dimensional black holes like those in our universe. A common concern, however, is that the authors might be reading too much meaning into this abstract calculation

Magnetars

For each chunk, the team extracted information about the elemental composition of the gases there, creating a more accurate picture of the supernova remnant’s composition than if they had averaged over the whole. They estimated that the supernovas came from stars between 10 and 20 times the mass of the sun — which means they were less massive than what’s needed to give birth to dynamo-powered magnetars.

Space Dust Ice Age

466m years ago, there was a very, very large asteroid impact. But, despite what you’re thinking, it actually helped life on Earth be fruitful and multiply. And that’s because the asteroid impact wasn’t on Earth. It was in the inner asteroid belt. A new paper points the accusatory finger at… dust. A lot of it, blasted outward when 2 big asteroids collided. This dust made its way to Earth, blocked a significant fraction of warming sunlight, started an ice age, and that put stress on marine environments which caused a burst of evolutionary diversity.

Fast Revolutions

Everything about this system is extreme. But it’s the stars themselves that get to me. Think of it this way: The Earth’s gravity is strong enough to keep the Moon going around it with an orbital period of a little over 27 days. At the same distance, J17062’s gravity whips its companion around over 1000x faster.