2020
March
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Today’s forecast: cloudy with a 100% chance of iron rain in the evening

The exoplanet, WASP-76b, about 640 light-years from Earth, orbits its host star, WASP-76, once every approximately 1.8 days at the relatively small distance of only 0.03 astronomical units (AU). The Earth, in contrast, is at a distance of 1 AU from the Sun. The star, WASP-76, is somewhat larger and hotter than the Sun, but that doesn’t make much of a difference for the planet orbiting around it. At such a small distance, the planet would be damn hot no matter how big the star was. The planet, almost as massive as our Jupiter, is therefore classified as a “Hot Jupiter.” The huge amount of heat has greatly inflated this alien world; WASP-76b has a diameter significantly larger than our Jupiter.

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Hexaquark d*(2380): a new candidate for dark matter

One of the biggest mysteries of our universe is what is dark matter made of. Its existence is suggested by several astronomical observations, among them peculiarities in the rotation of galaxies. Dark matter would have to make up at least 63% of all matter in the universe and to date, physicists have no idea about its exact nature.

All that is clear is that dark matter interacts with normal matter only via gravity. These could be, among other things, so-called WIMPs (Weakly Interacting Massive Particles), which would be considered cold dark matter. However, researchers are not making very quick progress on their search for these particles. To date, they have only been able to rule out more and more possible candidates, which is gradually making it more and more unlikely that they are actually on the right track.

Now, in an article in the Journal of Physics, researchers have presented a new candidate. This is a so-called hexaquark: a particle consisting of six quarks, the basic building blocks of many elementary particles. Three up and down quarks, its lightest variants, combine to form a d*(2380) hexaquark. For a long time, hexaquarks were considered hypothetical; in 2014, the first was discovered, d*(2380), at the Jülich Research Center. d*(2380) has a mass of 2380 MeV and is thus heavier, but due to its structure, more compact than a proton, the nucleus of a hydrogen atom.

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Bad news for life on Titan – or not?

So that life as we know it can emerge, it must be able to differentiate itself somehow from its environment. Therefore, every cell needs a shell that allows nutrients to pass through it from the outside, but nevertheless protects the cell’s insides from the outside world. On Earth, cell membranes perform this function and are made from lipids, hydrocarbon compounds that include, among other things, fatty acids.

On Saturn’s moon, Titan, it is much too cold, at an average temperature of -180 °C, for the formation of lipids. But there is a different class of substances there that astrobiologists had hoped could take on the function of lipids: acrylonitrile. Molecules of this substance could combine to form so-called azotosomes, whose properties are similar to those of lipids. In fact, it has already been shown that azotosomes could exist on Titan – and there was no lack of its starting material, acrylonitrile.

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Why the star of Orion’s left shoulder is fading

Betelgeuse is a red supergiant. With a diameter 1000 times that of the Sun’s and – formerly – 10,000 times the illuminance, it has wowed the entire Milky Way, but now it’s even being mentioned on the cable news shows. Why? Because everyone’s hoping for a catastrophe. If such a large star fades to 36 percent of its previous illuminance within a short time, it would suggest it might soon end in a supernova. That would certainly be spectacular, because it would grace the Earth’s night skies with the brightness of a half moon.

But the hope that this fireworks display will go off sometime in our lifetime is probably still too premature. Astronomers of the European Southern Observatory have shown with the help of the Very Large Telescope that Betelgeuse really has changed in apparent shape and brightness (see the images below). But that could also be due to a giant dust cloud ejected by the star, which is more than 700 light-years away, obscuring our view. It could also be possible that the surface has cooled significantly due to some unusual stellar activity.

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NASA wants to visit Triton, Io, and Venus

NASA has unveiled four new research missions that could set flight under the Discovery Program – if their feasibility can be confirmed. They highlight three locations that you will already know from my books: Venus (two proposals), Io, and Triton. However, a maximum of two of the four proposals will be developed.

Here are the details:

DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus)

DAVINCI+ will analyze Venus’s atmosphere in order to understand how it formed and developed and whether Venus ever had an ocean. To do this, DAVINCI+ will plunge into Venus’s inhospitable atmosphere and precisely measure its composition down to the surface. Its instruments will be housed in a ball specially constructed to protect the instruments from Venus’s intense conditions during the descent. The “+” in DAVINCI+ refers to the mission’s imaging components, including cameras on the descent ball and an orbiter designed for mapping the types of rocks on the surface. The last NASA mission to Venus took place in 1978.

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Cosmic strings and our existence in the universe

The Big Bang was the beginning of this, our universe. Astrophysicists agree on that much at least. Whether it was or will be the only event of this type is a debate for philosophers. But there are still a few unresolved questions involving the Big Bang. The most important of these would probably be: why do we exist at all? Because after all the four fundamental forces finally developed after the Big Bang, matter and antimatter should always be formed in exactly the same amount. The evolution of the universe would thus be relatively boring: matter and antimatter would mutually destroy each other and the universe would remain as empty as if nothing had ever existed. People? That’s an indication something went wrong.

Now, we have to admit that quite objectively we do exist (unless you subscribe to the conjecture that our world is only a simulation). Therefore, the expected sequence of the Big Bang must have been slightly different from what we expected. More matter than antimatter was formed, eventually leading to us. But why should the universe have preferred matter over antimatter? Nobody has come up with a reason yet that has been convincing for all researchers.

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Sleeping monster from the early days of the universe

At first glance, XMM-2599 appears to be a rather boring galaxy (because it’s dying). But an international research team has recently discovered that it’s really a sleeping monster. XMM-2599 formed more than 12 billion years ago, when the universe was still very young, only 1.8 billion years old. At first the galaxy was extremely active. “Even before the universe was 2 billion years old, XMM-2599 had already formed a mass of more than 300 billion suns, making it an ultramassive galaxy,” says Benjamin Forrest, lead author of the study in Astrophysical Journal.

“More remarkably, we show that XMM-2599 formed most of its stars in a huge frenzy when the universe was less than 1 billion years old – and then became inactive,” explains Forrest. The team found that XMM-2599 produced 1000 solar masses in stars per year during its most active period. In contrast, the Milky Way produces only one new star per year.

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