Another oldie from my draft folder. I’d like to do a mass deletion of 99% of my unposted drafts.
An impressive impact crater on Mars, observed by NASA’s Mars Reconnaissance Orbiter, November 19, 2013. (NASA)
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
The Sun, as of March 1, 2016.
and now there’s TWO John Scalzi covers. https://gumroad.com/sparth
Lynds Dark Nebula 1251 : Stars are forming in Lynds Dark Nebula (LDN) 1251. About 1,000 light-years away and drifting above the plane of our Milky Way galaxy, the dusty molecular cloud is part of a complex of dark nebulae mapped toward the Cepheus flare region. Across the spectrum, astronomical explorations of the obscuring interstellar clouds reveal energetic shocks and outflows associated with newborn stars, including the telltale reddish glow from scattered Herbig-Haro objects seen in this sharp image. Distant background galaxies also lurk on the scene, buried behind the dusty expanse. This alluring view imaged with a backyard telescope and broadband filters spans about two full moons on the sky, or 17 light-years at the estimated distance of LDN 1251. via NASA
Star Tunnel - 220319
Pulling Away.
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”I didn’t feel like a giant. I felt very, very small.”
–Neil Armstrong on looking back at the Earth from the Moon in July 1969.
(Sources: 1, 2)