The Sun, As Of August 12, 2015.

The Sun, as of August 12, 2015.

Boo-tiful Ring Galaxies

A ghoulish secret lurks within each of these gorgeous galaxies. Their rings are dotted with stellar graveyards!

These objects are called ring galaxies, and scientists think most of them form in monster-sized crashes. Not just any galaxy collision will do the trick, though. To produce the treat of a ring, a smaller galaxy needs to ram through the center of a larger galaxy at just the perfect angle.

The collision causes ripples that disturb both galaxies. The gravitational shock causes dust, gas, and stars in the larger galaxy’s disk to rush outward. As this ring of material plows out from the galaxy’s center, gas clouds collide and trigger the birth of new stars.

In visible light, the blue areas in the galaxies’ rings show us where young, hot stars are growing up. Faint, pink regions around the ring mark stellar nurseries where even younger stars set hydrogen gas aglow.

The newborn stars come in a mix of sizes, from smaller ones like our Sun all the way up to huge stars with tens of times the Sun’s mass. And those massive stars live large!

While a star like our Sun will last many billions of years before running out of fuel, larger stars burn much brighter and faster. After just a few million years, the largest stars explode as supernovae. When massive stars die, they leave behind a stellar corpse, either a neutron star or black hole.

When we turn our X-ray telescopes to these ring galaxies, we see telltale signs of stellar remnants dotted throughout their ghostly circles. The purple dots in the X-ray image above are neutron stars or black holes that are siphoning off gas from a companion star, like a vampire. The gas reinvigorates stellar corpses, which heat up and emit X-rays. These gas-thirsty remains are beacons lighting the way to stellar graveyards.

Spiral galaxies — like our home galaxy, the Milky Way — have curved arms that appear to sweep out around a bright center. The dust and gas in those spiral arms press together, causing cycles of star formation that result in a more even mix of new stars and stellar corpses scattered throughout our galaxy. No creepy ring of stellar corpses here!

To visit some other eerie places in the universe, check out the latest additions to the Galaxy of Horrors poster series and follow NASA Universe on Twitter and Facebook for news about black holes, neutron stars, galaxies, and all the amazing objects outside our solar system.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

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epic-flight

4 years ago

Allegiance-class Star Destroyer - Ansel Hsiao

Allegiance-class Star Destroyer - Ansel Hsiao

1K notes View Post

epic-flight

4 years ago

Chaos theory, the principles underpinning certain nonlinear equations, also requires us to adopt a probabilistic description of many natural phenomena. The sizes and orbital positions of the planets in our solar system, for example, depend sensitively on the starting condition for solar system formation. If we ran the creation experiment again with slightly different parameters, we would get a different collection of planets with different orbital characteristics. But the results are not purely random. If we produced thousands of solar systems, again with similar but not exactly the same starting conditions, we would obtain a well-defined distribution of planet properties and planetary orbits. Although we cannot make exact predictions for any particular experiment, in principle we can determine the odds of getting any one type of planet or solar system. This intricate interplay between chance and determinism occurs throughout our physical universe and can even be applied to the consideration of how, and in what form, life can evolve.

Fred Adams, ‘Origins Of Existence: How Life Emerged In The Universe’ (2002)