Astrophysics

Giu 18 2019

How does a radio telescope work? A visit to the Very Large Array

Every – okay, almost every – object in the universe emits light. When astronomers talk about light, however, they’re not only talking about the small portion of the entire electromagnetic spectrum that humans can see, i.e., the optical range, but instead they’re talking about all of it: radio waves, infrared, visible light, UV light, X-rays, gamma radiation (listed here in order of decreasing wavelength). Physicists would call this “electromagnetic radiation,” but “light” also fits very well, because, in the end, the same laws always apply for reception. Resolution, focal length, etc., it doesn’t matter if you are using a…

The first star explosions were gigantic – and asymmetrical

Astrophysics

Mag 17 2019

The first star explosions were gigantic – and asymmetrical

After a star with significantly more mass than the Sun has consumed all its fuel, it decays into a massive firework display, a supernova. In today’s universe, that is not a very common sight, because the greatest percentage of stars is made up of red dwarfs, which end their lives not nearly so spectacularly. Our Sun is also not destined to turn into a supernova. It will grow into a red giant and then, at the end, only a harmless white dwarf will remain. In the early universe, however, things were much different. At that time, there were neither…

Two values for one constant – impossible, but true

Astrophysics

Mag 15 2019

Two values for one constant – impossible, but true

The universe is expanding. That’s something astronomers have agreed on for a long time. Edwin Hubble, an American astronomer, was the first to discover that light from distant galaxies was shifted toward red frequencies by the time it reached us – which meant that the source of the light was moving away from us. The Hubble constant, which expresses how quickly the universe is expanding, was named in Hubble’s honor. It has a value of approximately (more on this later) 70 kilometers per second per megaparsec. For example, if an object is one million parsecs (3.26 million light-years) farther…

Airborne telescope detects helium hydride ion in space

Astrophysics

Apr 25 2019

Airborne telescope detects helium hydride ion in space

The helium hydride ion HeH+ is a puzzle in and of itself. As a noble gas, helium does not easily bond with other elements. And in the early universe, the selection of elements was much smaller than it is today: the only elements were hydrogen (H), helium (He), and traces of lithium, and only in ionized form, that is, without electrons, which form the basis for chemical bonds. After the big bang, the universe had to cool down first, for a period of approximately 300,000 years, before chemistry could begin. At a temperature of about 3700 degrees Celsius, the…

Astrophysics

Apr 14 2019

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

Apr 9 2019

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

Apr 7 2019

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…

Astrophysics

Mar 20 2019

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…