Brian Koberlein, Author at Universe Today

November 28, 2020November 29, 2020 by Brian Koberlein

Neutrinos prove the Sun is doing a second kind of fusion in its core

The central nylon balloon of the Borexino Detector. Credit: The Borexino Collaboration

Like all stars, our Sun is powered by the fusion of hydrogen into heavier elements. Nuclear fusion is not only what makes stars shine, it is also a primary source of the chemical elements that make the world around us. Much of our understanding of stellar fusion comes from theoretical models of atomic nuclei, but for our closest star, we also have another source: neutrinos created in the Sun’s core.

November 25, 2020November 25, 2020 by Brian Koberlein

Solar astronomers can now predict future sunspots. There should be a big one in a couple of days

Sunspot image from the newly upgraded GREGOR Telescope

The surface of the Sun is a turbulent dance of gravity, plasma, and magnetic fields. Much like the weather on Earth, its behavior can seem unpredictable, but there are patterns to be found when you look closely.

November 23, 2020November 23, 2020 by Brian Koberlein

Gravitational lenses could be the key to measuring the expansion rate of the Universe

Illustration of gravity waves from a neutron star merger. Credit: NRAO/AUI/NSF

One of the tenets of our cosmological model is that the universe is expanding. For reasons we still don’t fully understand, space itself is stretching over time. It’s a strange idea to wrap your head around, but the evidence for it is conclusive. It is not simply that galaxies appear to be moving away from us, as seen by their redshift. Distant galaxies also appear larger than they should due to cosmic expansion. They are also distributed in superclusters separated by large voids. Then there is the cosmic microwave background, where even its small fluctuations in temperature confirm cosmic expansion.

November 19, 2020November 19, 2020 by Brian Koberlein

Some of the Milky Way’s oldest stars aren’t where they’re expected to be

Representation of the orbit of the star 232121.57-160505.4. Credit: Cordoni, et al

One of the ways we categorize stars is by their metallicity. That is the fraction of heavier elements a star has compared to hydrogen and helium. It’s a useful metric because the metallicity of a star is a good measure of its age.

November 18, 2020November 18, 2020 by Brian Koberlein

Astronomers think they’ve seen a magnetar form for the first time; the collision of two neutron stars

Artist view of a kilonova producing a magnetar. Credit: NASA, ESA, and D. Player (STScI)

A magnetar is a neutron star with a magnetic field thousands of times more powerful than those of typical neutron stars. Their fields are so strong that they can generate powerful, short-duration events such as soft gamma repeaters and fast radio bursts. While we have learned quite a bit about magnetars in recent years, we still don’t understand how neutron stars can form such intense magnetic fields. But that could soon change thanks to a new study.

November 13, 2020November 13, 2020 by Brian Koberlein

Do neutron star collisions produce black holes?

neutron star merger and gamma ray burst — Artistic representation of two merging neutron stars. Credit: Dana Berry, SkyWorks Digital, Inc.

In principle, creating a stellar-mass black hole is easy. Simply wait for a large star to reach the end of its life, and watch its core collapse under its own weight. If the core has more mass than 2 – 3 Suns, then it will become a black hole. Smaller than about 2.2 solar masses and it will become a neutron star. Smaller than 1.4 solar masses and it becomes a white dwarf.

November 10, 2020November 10, 2020 by Brian Koberlein

Brown dwarf discovered with a radio telescope for the first time

Artist view of a cool brown dwarf. Credit: ASTRON / Danielle Futselaar

Brown dwarfs are interesting objects. They are generally defined as bodies massive enough to trigger the fusion of deuterium or lithium in their cores (and are thus not a planet) but too small to fuse hydrogen in their cores (and therefore not a star). They are the middle children of cosmic bodies.

November 7, 2020November 7, 2020 by Brian Koberlein

One Mars Trojan asteroid has the same chemical signature as the Earth’s moon

The trojan asteroids of Mars. Credit: Armagh Observatory

Although Mars is much smaller than Earth, it has two moons. Deimos and Phobos were probably once asteroids that were captured by the gravity of Mars. The red planet has also captured nine other small bodies. These asteroids don’t orbit Mars directly, but instead, orbit gravitationally stable points on either side of the planet known as Lagrange points. They are known as trojans, and they move along the Martian orbit about 60° ahead or behind Mars. Most of these trojans seem to be of Martian origin and formed from asteroid impacts with Mars. But one of the trojans seems to have a different origin.

November 4, 2020November 4, 2020 by Brian Koberlein

Even older red dwarf stars are pumping out a surprising amount of deadly radiation at their planets

Measuring x-rays from red dwarfs. Credit: NASA/CXC/M. Weiss

Most of the potentially habitable exoplanets we’ve discovered orbit small red dwarf stars. Red dwarfs make up about 75% of the stars in our galaxy. Only about 7.5% of stars are g-type like our Sun. As we look for life on other worlds, red dwarfs would seem to be their most likely home. But red dwarfs pose a serious problem for habitable worlds.

October 30, 2020October 30, 2020 by Brian Koberlein

Something other than just gravity is contributing to the shape of dark matter halos

The simulated distribution of dark matter in galaxies. Credit: Brinckmann et al.

It now seems clear that dark matter interacts more than just gravitationally. Earlier studies have hinted at this, and a new study supports the idea even further. What’s interesting about this latest work is that it studies dark matter interactions through entropy.