Hubble Views The Final Frontier For Dark Matter

“This phenomenon of gravitational lensing stretches galaxies into streaks and arcs, magnifying them, and creating multiple images. It also enables us to reconstruct the mass distribution of the cluster, revealing that it’s mostly due to dark matter.”

When you look out at the distant Universe, you can see all sorts of things: stars, galaxies, clusters of galaxies, going as far back into the distant past as our telescopes can image. But where you have the greatest concentrations of mass, an extreme phenomenon emerges: that of gravitational lensing. Any foreground objects lying behind that mass will have their light stretched, magnified and distorted by the intervening matter. Recently, as part of the Hubble Frontier Fields program, the telescope followed-up on galaxy cluster Abell 370, and revealed the most spectacular gravitational lensing signal ever seen in a galaxy cluster. Most importantly, it provides some very strong evidence not only for dark matter’s existence, but for its presence distinct from any galaxies at all.

Come get the full story in images, videos, and no more than 200 words on this edition of Mostly Mute Monday!

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“paper works”, Hannah Reber, 2013, Berlin

Where Your Elements Came From

The hydrogen in your body, present in every molecule of water, came from the Big Bang. There are no other appreciable sources of hydrogen in the universe. The carbon in your body was made by nuclear fusion in the interior of stars, as was the oxygen. Much of the iron in your body was made during supernovas of stars that occurred long ago and far away. The gold in your jewelry was likely made from neutron stars during collisions that may have been visible as short-duration gamma-ray bursts. Elements like phosphorus and copper are present in our bodies in only small amounts but are essential to the functioning of all known life. The featured periodic table is color coded to indicate humanity’s best guess as to the nuclear origin of all known elements. The sites of nuclear creation of some elements, such as copper, are not really well known and are continuing topics of observational and computational research.

Image Credit: Cmglee (Own work) CC BY-SA 3.0 or GFDL, via Wikimedia Commons

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hannahhaifisch

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Where you will find me today { @ NASA } contemplating formations like ‘cloud streets’ like this activity over the Bering Sea | 📷via @explorenasa + NASA/Goddard | research for #spacelandings2017 #atmosphericresearch #newterrain #environment #sciencematters { cylinders of #spinning #air }

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hannahhaifisch

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Water Is One Of Those Strange Materials That Expands When It Freezes, Which Raises An Interesting Question:

Water is one of those strange materials that expands when it freezes, which raises an interesting question: what happens to a water drop that freezes from the inside out? A freezing water droplet quickly forms an ice shell (top image) that expands inward, squeezing the water inside. As the pressure rises, the droplet develops a spicule – a lance-like projection that helps relieve some of the pressure.

Eventually the spicule stops growing and pressure rises inside the freezing drop. Cracks split the shell, and, as they pull open, the cracks cause a sudden drop in pressure for the water inside (middle image). If the droplet is large enough, the pressure drop is enough for cavitation bubbles to form. You can see them in the middle image just as the cracks appear.

After an extended cycle of cracking and healing, the elastic energy released from a crack can finally overcome surface energy’s ability to hold the drop together and it will explode spectacularly (bottom image). This only happens for drops larger than a millimeter, though. Smaller drops – like those found in clouds – won’t explode thanks to the added effects of surface tension. (Image credit: S. Wildeman et al., source)

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hannahhaifisch

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