Astrophysics

A radio view into a black hole’s backyard Astrophysics

A radio view into a black hole’s backyard

By definition, black holes themselves remain shut off from direct observation. But astronomers have been able to precisely image the sphere of influence of a black hole – the area in which its gravity is the dominant force. In the case of a supermassive black hole in the interior of a galaxy, this area can be up to 500 light-years across. For comparison, the closest star to the Sun is a good four light-years away. This imaging was done by the Atacama Large Millimeter/submillimeter Array (ALMA) in the Atacama desert of Chile. NGC 3258, a giant elliptical galaxy about…
How our Milky Way was born Astrophysics

How our Milky Way was born

13 billion years ago, the universe looked quite different. Stars formed in rapid sequence and joined to form dwarf galaxies that grew bigger through collisions with each other, in order to finally become the massive galaxies we see today. Our Milky Way was formed through a similar process. Spanish researchers at the Instituto de Astrofísica de Canarias (IAC) have now succeeded in retracing the development of our home galaxy using data from the Gaia satellite. To do this, the astronomers compared the position, brightness, and distance of a million stars within a 6,500 light-year sphere. In this way, they…
Have you ever seen a moon being born? Astrophysics

Have you ever seen a moon being born?

It starts with a cloud of gas and dust. The cloud contracts into a disk and a star ignites at its center. Planetoids form around the star in the protoplanetary disk and grow into planets. Around the planets, in turn, are dust disks that eventually form moons. Up to that last step, this theory of solar system formation had long been confirmed by observations. But no telescope had yet discovered a dust disk around a planet. Now one has. ALMA, the Atacama Large Millimeter/submillimeter Array made the first such observation in the young solar system of PDS 70, which is…
Old and young at the same time? The mystery of red giants Astrophysics

Old and young at the same time? The mystery of red giants

At the end of their life, main sequence stars (which also include our Sun) develop into red giants. This fate is predestined for them. However, it’s not so easy to figure out the true age of a red giant. This is because there are many individual factors that can accelerate or slow down their development. Astronomers have gotten rather good at this in recent years, but there are always exceptions. Four years ago, researchers of the Leibniz Institute for Astrophysics and the Max Planck Institute for Astronomy discovered red giants whose age estimates differed by up to four billion…
How does a radio telescope work? A visit to the Very Large Array Astrophysics

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

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

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

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…