Hard Science Fiction

2020

January

2020
January

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How the ice moon Enceladus got its tiger stripes

By Brandon Q. Morris • On 12/20/2019 • In Enceladus, Life • 2 min read

Saturn’s ice moon, Enceladus, is one of the most promising worlds in terms of the search for places where extraterrestrial life might exist. Of course, as a reader of the Ice Moon series, you’ve already known that for a long time. Near its south pole there are deep fissures in its crust, through which water is constantly being forced outward. This allows researchers to look under the ice, which is up to 100 kilometers thick, without having to drill through it. A new study tries to explain the unusual appearance of these sulci, which are also called “tiger stripes.”

“First seen by the Cassini mission, these stripes are like nothing else known in our Solar System,” says Doug Hemingway, primary author of the article in Nature Astronomy. “They are parallel and evenly spaced, about 130 kilometers long and 35 kilometers apart. What makes them especially interesting is that they are continually erupting with water ice, even as we speak. No other icy planets or moons have anything quite like them.”

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Three giant black holes at the center of one galaxy

By Brandon Q. Morris • On 12/18/2019 • In Astrophysics, Space • 2 min read

At the center of any galaxy that wants to be taken seriously, a mysterious giant is lurking – a supermassive black hole, often with a mass of millions to billions of solar masses. The center of our Milky Way has a gravitational monster, Sagittarius A*, which has sucked up the mass of more than four million stars the size of our Sun.

But in terms of the universe, that’s almost nothing. Astronomers have now identified three supermassive black holes in the irregular galaxy NGC 6240 as reported by the University of Göttingen. NGC 6240 is about 330 million light-years from the Solar System in the constellation Ophiuchus and has a diameter of about 300,000 light-years. Its irregular shape indicates that it was formed a relatively short time ago – perhaps only 30 million years ago – in a gigantic collision of galaxies.

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Hot and cold: an ice giant orbiting a white dwarf

By Brandon Q. Morris • On 12/16/2019 • In Astrophysics • 3 min read

In a few billion years, when our Sun has exhausted its supply of fuel, it will first turn into a red giant and then collapse to form a white dwarf. Some planets of our Solar System will probably survive this time (if they’re not flung out into deep space). Astronomers know this will happen – theoretically. But until now, nobody had ever found a white dwarf with a planet in orbit around it.

So, it’s understandable why researchers are so excited about the discovery of WDJ0914+1914, which is located in the constellation Cancer about 1500 light-years away. “It was one of those chance discoveries,” says the researcher Boris Gänsicke from the University of Warwick in the United Kingdom. The research group that he leads inspected about 7000 white dwarfs. With WDJ0914+1914, they noticed some peculiar features. By analyzing the slight oscillations in the starlight, the researchers found traces of chemical elements in quantities that nobody had ever observed in a white dwarf before. “We knew that there had to be something exceptional going on in this system and speculated that it might be related to some type of planetary remnant.”

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When a black hole is simply too big

By Brandon Q. Morris • On 12/14/2019 • In Astrophysics, Space • 2 min read

One of the distinguishing features of black holes is that they are hard to see. Astronomers looking for them sometimes have luck, but at the cost a star: when a ravenous black hole tears off and devours stellar material from an orbiting star, the resulting accretion disk emits radiation that can be measured. Almost all known black holes have been discovered this way.

But it seems logical that those aren’t the only ones out there. Black holes are formed when heavy stars die. And many of these giant stars die alone, without a companion that a resulting black hole could nibble on. Thus, presumably the known black holes represent just a selection – a selection that might not be representative in all aspects.

Chinese astronomers have now succeeded in finding a black hole the way planets are discovered: by its influence on the motion of a visible star. Here, the researchers bumped into a surprise that doesn’t fit nicely into current theories of star formation.

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How exoplanets develop in multiple-star systems

By Brandon Q. Morris • On 12/12/2019 • In Astrophysics, Space • 3 min read

In the novel, “The Three-Body Problem,” a civilization that developed in a system with three stars plays an important role. This situation has dramatic consequences for the civilization’s planet, which I don’t want to spoil for you. I was reminded of the novel when I read a press release of research work at the University of Jena. Dr. Markus Mugrauer, an astrophysicist there, examined 1300 known star systems with exoplanets to determine how many stars there were within these systems. To do this, he used the most up-to-date version of the data from the ESA Gaia Mission.

A clever approach that also produced some interesting insight into how the existence of multiple stars in a system affected the development of planets. In our Solar System, for example, the existence of a second Sun would have undoubtedly had dire consequences for humankind.

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Water detected on one of Jupiter’s moons, Europa

By Brandon Q. Morris • On 12/10/2019 • In Life, Space • 1 min read

The hottest candidates for the development of extraterrestrial life are one of Saturn’s moons, Enceladus, and one of Jupiter’s moons, Europa – even though it’s very cold on its surface. Life, in fact, might be hiding in an underground ocean under the 50-100 kilometer thick layer of ice. Its existence is indicated, among other things, by the countless fault lines criss-crossing across its surface.

Proof of this underground sea, however, has not yet been found. But now, with the help of the Keck Telescope on Mauna Kea (Hawaii), astronomers have found more evidence, as they have written in an article.

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A black-hole Sun: planets could also form around black holes

By Brandon Q. Morris • On 12/08/2019 • In Space • 1 min read

What does a builder of worlds need to form planets? A protoplanetary disk made out of a suitable material in which differences in density can develop, and an object at the center of the system that acts as a common center of gravity and uses its force of attraction to prevent the cloud of material from floating off into infinity. Until now it had been assumed that these conditions were met primarily by stars. But apparently much more exotic planetary systems are also conceivable, as Japanese researchers have now described in a study.

The scientists took a closer look at the conditions around black holes – and not just any black holes, but active galactic nuclei in particular. These are black holes that have masses of millions of solar masses and interact with their surroundings. Just like young stars, dust disks can form around them in gigantic dimensions. Just the dust disk itself can reach a mass of 100,000 Suns, corresponding to about a billion times the mass of a normal protoplanetary disk. Thus, there is plenty of material, and there’s also an energy source at the center.