Hubble releases shimmering image of a youthful globular cluster

  Globular clusters offer some of the most spectacular sights in the night sky. These ornate spheres contain hundreds of thousands of stars, and reside in the outskirts of galaxies. The Milky Way contains over 150 such clusters — and the one shown in this NASA/ESA Hubble Space Telescope image, named NGC 362, is one of the more unusual ones. As stars make their way through life they fuse elements together in their cores, creating heavier and heavier elements — known in astronomy as metals — in the process. When these stars die, they flood their surroundings with the material they have formed during their lifetimes, enriching the interstellar medium with metals. Stars that form later therefore contain higher proportions of metals than their older relatives. By studying the different elements present within individual stars in NGC 362, astronomers discovered that the cluster boasts a surprisingly high metal content, indicating that it is younger than expected. Although most globular clusters are much older than the majority of stars in their host galaxy, NGC 362 bucks the trend, with an age lying between 10 and 11 billion years old. For reference, the age of the Milky Way is estimated to be above 13 billion years. This image, in which you can view NGC 362’s individual stars, was taken by Hubble’s Advanced Camera for Surveys (ACS).

Recent revised estimates upping the number of galaxies in the universe seem even more mind-boggling when contemplating this image released from Hubble this week. It shows NGC 362, one of about 150 globular clusters on the outskirts of just one galaxy, our own Milky Way. Read the rest

More than 2 trillion galaxies in the universe, at least 10 times as many as we thought


In the 1990s, Hubble surprised astronomers by revealing just how packed the universe is with galaxies: they estimated some 200 billion of them based on its observations. But now we know these estimates were wrong. There are at least 2 trillion.

Conselice and his team reached this conclusion using deep-space images from Hubble and the already published data from other teams. They painstakingly converted the images into 3-D, in order to make accurate measurements of the number of galaxies at different epochs in the universe's history. In addition, they used new mathematical models, which allowed them to infer the existence of galaxies that the current generation of telescopes cannot observe. This led to the surprising conclusion that in order for the numbers of galaxies we now see and their masses to add up, there must be a further 90 percent of galaxies in the observable universe that are too faint and too far away to be seen with present-day telescopes. These myriad small faint galaxies from the early universe merged over time into the larger galaxies we can now observe.

"It boggles the mind that over 90 percent of the galaxies in the universe have yet to be studied. Who knows what interesting properties we will find when we discover these galaxies with future generations of telescopes? In the near future, the James Webb Space Telescope will be able to study these ultra-faint galaxies, said Conselice.

That's good for about 700 billion trillion stars, and heaven knows how many planets. (Previously) Read the rest

"Images" from the edge of a black hole

EDIT: This post originally went up with the wrong images. Sorry about that.

This is not a photograph.

But it's still amazing.

An important thing to remember about science is that some of the stuff we talk about in the general public as "fact" — like, say, black holes — haven't actually been seen by anybody. Instead, black holes exist on paper, as part of theoretical astrophysics. They also exist in indirect evidence — we can look for things in the universe that should exist in a certain way, in a certain place, if our theoretical astrophysics is correct. So far, that lines up, too.

And then there's this thing. Like I say, it's not a photo. It's more like a model. Telescopes — the kind we point at deep space — don't collect images, they collect information. This is a digital rendering made based on information collected when researchers pointed four different telescopes at a galaxy called (poetically) galaxy M87. What you're looking at is a series of simulations, over time, showing massive ribbons of gas undulating and spinning around the something at the galaxy's center. If the theoretical astrophysics is right, this is the closest we've ever gotten to seeing a black hole. Read the rest