Astrophysics

What dark matter is (not) made of Astrophysics

What dark matter is (not) made of

“When you have eliminated the impossible, whatever remains, however improbable, must be the truth,” the detective, Sherlock Holmes, says to Dr. Watson in “The Sign of the Four.” Cosmologists searching for dark matter, which should make up 85 percent of the universe’s mass, seem to be following a similar process right now. They are eliminating one component after another. Recently, they succeeded in eliminating two more possibilities. Dark matter is not made up of tiny black holes. This result was shown by astronomers with the help of the Japanese Subaru telescope. Their strategy was very interesting. According to theories…
The weather for HR 8799 e: 1000 degrees Celsius with clouds of iron and silicate dust Astrophysics

The weather for HR 8799 e: 1000 degrees Celsius with clouds of iron and silicate dust

HR 8799 e is a rather inhospitable place. The celestial body discovered in 2010 and orbiting the 30-million-year-young star HR 8799 at a distance of 129 light-years from Earth is a gas giant similar to Jupiter. But its host star shines nearly five times brighter than our Sun, creating a significantly hotter atmosphere for HR 8799’s innermost planet (despite the “e,” HR 8799 e is the closest planet to its host star) than Jupiter. That is quite astonishing because at approximately 14.5 AU, HR 8799 e is almost five times farther from its host star than Jupiter is from…
What does the interior of Neptune or Uranus look like? Astrophysics

What does the interior of Neptune or Uranus look like?

Exploring the interior of icy giant planets is not an easy task. Without more advanced technology, we won’t be able to use probes to make measurements on site, so researchers must rely on models. These models are based on what scientists know about the substances that make up these ice giants such as Neptune and Uranus. However, we can’t rule out that these models might contain errors. For example, it was previously assumed that carbon always took the form of diamond under very high pressures. Carbon and hydrogen are among the most abundant elements in the universe and make…
Physicists turn back time – a bit Astrophysics

Physicists turn back time – a bit

“Man! If only I could turn back time!” According to an article in the science magazine Scientific Reports, physicists have apparently succeeded in doing just that – at least in the quantum realm and with very small particles. However, it’s still impossible to manipulate the wheel of time, because the Second Law of Thermodynamics distinguishes between the past and the future. Most other physical laws are reversible. But when the Second Law comes into play, nature behaves very stubbornly, and everything progresses in only one direction. The house of cards collapses, it doesn’t build itself. Without external influences, heat…
How to look inside a black hole Astrophysics

How to look inside a black hole

When mass is so strongly concentrated that not even light can escape its gravitational field, physicists call this phenomenon a black hole. In reality, however, the name doesn’t quite fit its true physical nature. This is because some radiation, so-called Hawking radiation, is indeed emitted from a black hole. In addition, black holes set their surroundings in so much turmoil that in no way do they remain invisible: the matter falling into the hole forms an accretion disk around it, there are all kinds of swirling, turbulent magnetic fields – there’s little reason to fear falling into a black…
Why does dark matter behave differently in small galaxies than in large ones? Astrophysics

Why does dark matter behave differently in small galaxies than in large ones?

The most important characteristic of dark matter is that it interacts only by way of gravity. And as the only one of the four fundamental forces, gravity is always attractive. Therefore, no matter where it occurs, dark matter must always collect at the mass center of the respective structure, regardless of whether it is a small galaxy or a giant galaxy cluster. But in reality, things look quite different: in galaxy clusters, dark matter exhibits the expected behavior, but in smaller galaxies it is distributed much more widely than it should be. This arrangement could be explained in that…