2019
November
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Could an Earth-like planet also survive in an eccentric solar system?

HR5183 is a yellow dwarf star, not very different from our own Sun and located about 103 light-years from Earth. After more than 20 years of observation, astronomers finally found a planet, of about three times Jupiter’s mass, orbiting the star this past summer. Why did it take so long? The planet, HR5183 b, needs 75 years to complete one orbit around its star. Therefore, the period at which it affects the light curve of its star is also correspondingly long.

But what surprised the astronomers even more was the planet’s unusual orbit. HR5183 b comes about as close to its star as Jupiter’s distance to the Sun and then swings out to a distance far beyond that of Neptune’s orbit. Such an eccentric orbit had previously been observed only very rarely.

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New organic molecules discovered on Saturn’s moon Enceladus

Two years ago, the Cassini probe was sent plummeting into Saturn to its fiery demise – but researchers are still finding new discoveries in the data it sent back. Now, scientists from the Free University Berlin have reported findings from the CDA, the “Cosmic Dust Analyzer,” which was on board Cassini. This instrument was developed in Germany and was designed to study very small particles.

The CDA could detect particles with a velocity of 5 kilometers per second and a mass of only 1013 grams (a ten-millionth of a millionth of a gram, which corresponds to a size of two-thousands of a millimeter). In addition to the particle velocity and particle size (10 nanometers to 100 micrometers), it also determined the electrical charge of the particles and their basic composition.

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Will our Solar System soon have its sixth dwarf planet?

According to the definition of the International Astronomical Union (IAU), dwarf planets are celestial bodies that do indeed have the round shape of a planet, but do not have sufficient mass to dominate the area around their distance to the Sun. The most well-known example of a dwarf planet is surely Pluto (with a diameter of 2400 kilometers (1490 miles)). Eris, Makemake, and Haumea are three other dwarf planets orbiting in the outer regions of our Solar System. At 950 kilometers (590 miles), Ceres is the largest object in the Asteroid Belt and simultaneously the smallest dwarf planet.

But maybe not for much longer, because the asteroid Hygiea also appears to be approximately spherical. The asteroid discovered by Annibale de Gasparis on April 12, 1849 in Naples was named after Hygieia, the daughter of the god Asclepios from Greek mythology. It is only the fourth largest object in the Asteroid Belt. However, differently than the somewhat larger asteroids, Vesta and Pallas, it actually appears to be spherical, as observations with the SPHERE instrument of the Very Large Telescope of the European Southern Observatory, ESO, have shown.

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How much energy can we borrow from a vacuum?

Negative energy doesn’t exist; that’s what we learned in school. If it did, then there’d also have to be negative mass – and thus a repulsive gravitational force, because energy and mass are directly linked with each other, as Einstein showed in his theory of relativity. At the micro-level, however, that’s not true (and that’s one of the reasons why physicists are still having a lot of fun trying to unite relativity and quantum theory). In extremely small areas, it is possible for energy to fall below zero for a short time, so that we are essentially borrowing energy from a vacuum. Science fiction authors like to use this idea to fabricate all sorts of cheap energy sources.

But a vacuum is rather stingy. It gives energy credits only up to a certain limit, and even demands a so-called “quantum interest.” The exact value of this amount is currently unknown. In any case, like in traditional banking, the “quantum interest” owed depends on the amount and term of the credit. However, the relationship is not linear, not at all. By all accounts, the universe is an extortioner and the interest amounts quickly balloon even when the term or credit amount increases only slightly. This ensures that going into debt doesn’t become commonplace in a vacuum and existing credits are paid back quickly, so everything remains in balance statistically.

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How a universe made out of fuzzy dark matter might look

The exact composition of 84 percent of all the matter in the universe is unknown. That is the portion, called dark matter, which neither emits radiation nor interacts with conventional matter that we already know of in any other way than through gravity. Cosmologists believe they can use the standard model of the universe, Lambda-CDM, to get to the bottom of dark matter. This model assumes that dark matter is “cold” (cold dark matter – CDM).

In physics, “cold” means that something is moving slowly. So-called “WIMPs” (weakly interacting massive particles) would have to be previously unknown particles, heavier than anything we know of so far, and would be detectable only by means of their gravity. The fact that dark matter is gravitationally active is basically the only thing we know about it for sure. In fact, that’s how its existence was determined in the first place.

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At the end of the Solar System, there’s a surprisingly high pressure

Our Sun emits particles and radiation around the clock. These emissions propagate far into space in all directions and form the heliosphere. At the same time, our Solar System is constantly bombarded from interstellar space by cosmic radiation from a wide range of sources. Way out in the far outer edges of our Solar System, a few billion kilometers from the Sun, these streams of radiation meet each other from both directions in the so-called heliosheath.

The pressure appears to be significantly higher there than researchers previously thought. This was discovered by astronomers with the help of the two Voyager probes that have had only one goal since 1977 – to leave the Solar System. At the time of the measurements, Voyager 1 had already reached interstellar space (but was still within the Solar System as defined by its gravitational effects), while Voyager 2 was still flying through the heliosheath.

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How, not that long ago, the center of the Milky Way exploded

Right now, despite its 4.2 million solar masses, Sagittarius A*, the gigantic black hole at the center of the Milky Way, appears to be a harmless, sleeping giant. But that wasn’t always the case. If one of our ancestors, Australopithecus, had been able to observe the skies over Africa 3.5 million years ago (thus, long after the extinction of the dinosaurs) just as intensively as we can, he might have been able to witness a gigantic, approximately 300,000-year-long explosion in the center of the Milky Way, which created conical bursts of radiation extending through both poles of the galaxy out into interstellar space.

This observation is described by a team of researchers led by Professor Joss Bland-Hawthorn of the Australian ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) in the Astrophysical Journal (link to the full text). The phenomenon, a so-called Seyfert Flare, left its traces in the form of two enormous ionization cones that begin with a small diameter at the black hole and increase in size as they extend across the galaxy.

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