2019
July
Standard

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 years depending on the estimation method. “The stars appeared to be old and young at the same time,” recalled Dr. Saskia Hekker from MPS and the University of Aarhus in Denmark, who was a member of both teams at the time. The researcher was never able to let go of the paradox, and now, with her colleague Dr. Jennifer A. Johnson of Ohio State University, they’ve solved it. The giant stars are only faking their youthful age.

Read more

more
Standard

Interstellar medium as a filling station – a model calculation

In my book “Proxima Rising,” I describe how a spaceship, which at first is the size of a needle, is accelerated by powerful lasers to 20% of the speed of light. Then it increases its size by collecting material from its surroundings. But isn’t that totally unrealistic? Isn’t space just empty between the stars?

No. I’m sure you had already guessed that answer, because hopefully you know I’m trying hard to write scientifically possible science fiction. The vacuum in space is not empty. From a quantum-physics perspective, it is anything but, however I’m not referring to that. Normal interstellar space is full of matter. For the most part, this is hydrogen, but also any other element that was formed in a star and released in a supernova occurs in trace amounts.

How large are these trace amounts? Our Sun is moving, as far as we know, within a local interstellar cloud that is, in turn, located in a relatively empty region of the Milky Way. In comparison with its surroundings, there is a relatively large amount of matter in the local cloud (namely, 0.3 atoms per cm3). The average value in the Milky Way, however, is higher, at 0.5 atoms per cm3. Thus, in the volume of three sugar cubes, there would be approximately one atom in the space outside of our Solar System.

Read more

more
Standard

Launch of Dragonfly Mission to Saturn’s moon, Titan, planned for 2026

NASA just announced some great news for readers of the ice moon series: in 2026, so in just seven years, an innovative mission will be launched to Titan, a mission that will study the surface of the fascinating moon with the help of an autonomous drone. “Dragonfly” should find good flying conditions there – the atmospheric pressure at Titan’s surface is 50% higher than the air pressure at the Earth’s surface. Under those conditions, even a human in a wingsuit could fly under his or her own power, researchers believe, because Titan’s gravity (which is only slightly greater than Mercury’s) is also significantly less than here at home.

Read more

more