Category Astronomy/Space

To Stick or to Bounce: Size determines the Stickiness of Cosmic Dust Aggregates

Micrometer-scale dust particles from protoplanetary disks, or sites around stars with particles and hydrogen and/or other gasses, aggregate to form planetesimals, or kilometer-scale building blocks of planets. Planetesimals, in turn, merge due to mutual gravity. ©JAMSTEC

Microparticle dust aggregates, which are thought to play a role in the formation of new planets, are less likely to stick together after a collision when the aggregates are larger.

Current evidence suggests that microparticles of cosmic dust collide and stick together to form larger dust aggregates that may eventually combine and develop into planets...

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Ancient, High-Energy Impacts could have Fueled Venus Volcanism

Model showing Venus' high-energy impacts
An SwRI-led team compared the early impact history of Venus and Earth, determining that Venus experienced higher-energy impacts creating a superheated core. Models show these conditions could create Venus’ extended volcanism and younger surface.

Models show Venus’ superheated core could produce extended volcanism, long-lived resurfacing. A Southwest Research Institute-led team has modeled the early impact history of Venus to explain how Earth’s sister planet has maintained a youthful surface despite lacking plate tectonics. The team compared the early collision histories of the two bodies and determined that Venus likely experienced higher-speed, higher-energy impacts creating a superheated core that promoted extended volcanism and resurfaced the planet.

“One of the mysteries of t...

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Unusual White Dwarf Star is made of Hydrogen on one side and -Helium on the other

This artist's animation shows the two-faced white dwarf nicknamed Janus rotating on its axis. Janus is about 1,300 light-years away in the constellation Cygnus.

In a first for white dwarfs, the burnt-out cores of dead stars, astronomers have discovered that at least one member of this cosmic family is two faced. One side of the white dwarf is composed of hydrogen, while the other is made up of helium.

“The surface of the white dwarf completely changes from one side to the other,” says Ilaria Caiazzo, a postdoctoral scholar at Caltech who leads a new study on the findings in the journal Nature. “When I show the observations to people, they are blown away.”

White dwarfs are the scalding remains of stars that were once like our sun. As the stars age, they puff up into red giants; eventually, their outer fluffy material is blown away and their cores contract into dense, fiery-hot white dwarfs...

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The Puzzle of the Galaxy with No Dark Matter

Dark matter-free galaxy NGC 1277, located near the centre of the Perseus cluster, 240 million light-years from Earth. Credit: NASA, ESA, and M. Beasley (IAC)

A team of scientists, led by the researcher at the IAC and the University of La Laguna (ULL) Sebastién Comerón, has found that the galaxy NGC 1277 does not contain dark matter. This is the first time that a massive galaxy (it has a mass several times that of the Milky Way) does not show evidence for this invisible component of the universe. “This result does not fit in with the currently accepted cosmological models, which include dark matter” explains Comerón.

In the current standard model cosmology massive galaxies contain substantial quantities of dark matter, a type of matter which does not interact in the same way as no...

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