A unique star system where exoplanets orbit their star backwards located by researchers.
- Astrophysicists find a very rare system with two exoplanets orbiting their star backwards.
- The star system K2-290 is 897 light years away.
- In our Solar System, all the planets revolve in the same direction as the rotation of the Sun.
Astrophysicists discovered a very rare planetary system 897 light years away which features two exoplanets orbiting their star backwards. This unexpected arrangement is due to the tilting of the protoplanetary disk in which the planets were formed.
The researchers found that the two planets in the K2-290 system orbit around the star in almost the opposite direction as the star's rotation around its own axis. In our Solar System, by comparison, all the planets revolve in the same direction as the rotation of the Sun. K2-290 A's rotational axis is tilted by approximately 124 degrees in contrast to the orbits of the planets.
The international research team was led by Maria Hjorth and Simon Albrecht from the Stellar Astrophysics Centre of Aarhus University in Denmark, and also involved scientists from Princeton University, Pennsylvania State University, University of Toronto, and Tokyo Institute of Technology.
This actually isn't the first time a "backwards" planetary system like this has been spotted. One was sighted over 10 years ago. But, as one of the study's authors Joshua Winn from Princeton University explained in a press release, "this is a rare case in which we think we know what caused the drastic misalignment, and the explanation is different from what researchers have assumed might have happened in the other systems."
A protoplanetary disc was twisted almost 180° before planet formation.
Illustration: Christoffer Grønne.
The unusual formation of the planets was caused by the protoplanetary disk – a disk of material that spins around a young star for several million years after the star's birth. Normally, this spin is going in the same direction as the star but the gravitational force from a neighboring star can tilt the disk, which is what happened in this case.
Another author, PhD student Emil Knudstrup from Aarhus University, shared what drew him to this work:
"The idea that planets travel on wildly misaligned orbits has fascinated me throughout my graduate study. It is one thing to predict the existence of these crazy orbits, so very different from what we see in the Solar System. It is quite another thing to participate in actually finding them!"
Check out the paper "A backward-spinning star with two coplanar planets" published in the Proceedings of the National Academy of Sciences (PNAS).
New study figures out how stars produce gamma ray bursts.
- Researchers find out how binary star systems produce gamma ray bursts.
- Gamma ray bursts are the brightest explosions in the Universe.
- Tidal effects created in a binary system keep the stars spinning fast and create the bursts.
Giant space explosions capture our imaginations, even though they take place unimaginably far and reach us years later. Now, a team of astronomers figured out how gamma-ray bursts – the biggest and the brightest bangs in the Universe take place.
What the researchers from the University of Warwick in the UK understood is that tidal effects, like those between our own Moon and the Earth, can cause the enormous space explosions.
To arrive at their conclusions, the astronomers looked at simulated models of thousands of binary star systems, which are solar systems where two stars orbit each other. Over half of all stars reside in such arrangements.
The research showed that the spinning of stars in binary systems can cause conditions for a gamma-ray burst to take place.
Specifically, the long gamma-ray bursts (GRB) that the study looked at, happen when a gigantic star that's ten times bigger than our sun explodes. It goes supernova, collapsing into a neutron star or turning into a black hole, while shooting out a massive jet into space.
The scientists explain that what happens next is that the star flattens out into a disc, keeping its angular momentum. The star's material falls inwards but this momentum propels it out as a jet – along the polar axis, as explains the press release.
Cosmic death beams: Understanding gamma ray bursts
Another aspect that is important to the creation of the jet – the star has to spin fast enough to launch such materials. While normally stars would slow down their spin quickly, tidal effects from a neighboring star could keep the spin rate high enough to cause gamma-ray bursts.
This effect is similar to the spin interaction between the Earth and its Moon.
The study's lead author Ashley Chrimes, a PhD student in the University of Warwick Department of Physics, explained that the team's accomplishment is in figuring out how to predict what types of stars cause "the biggest explosions in the Universe."
"We found that the effect of a star's tides on its partner is stopping them from slowing down and, in some cases, it is spinning them up," Chrimes elaborated. "They are stealing rotational energy from their companion, a consequence of which is that they then drift further away."
In another takeaway, the scientists found that most of the fast-spinning stars are doing so because of being locked in a binary system.
The binary stellar evolution models used in the study were devised by researchers from the University of Warwick and Dr. J. J. Eldridge from the University of Auckland. Dr. Elizabeth Stanway from the University of Warwick's Department of Physics pointed out that the models are of previously-impossible sophistication and will be expanded further "to explore different astrophysical transients, such as fast radio bursts, and can potentially model rarer events such as black holes spiralling into stars."
Check out the paper on this discovery in the Monthly Notices of the Royal Astronomical Society.
Princeton scientists find a new way to control nuclear fusion reactions.
- A new study from Princeton physicists successfully uses boron powder to control nuclear reactions in plasma.
- Creating plasma can lead to an unlimited supply of energy.
- The new method is cheaper and less dangerous than previous approaches.
Humanity's huge appetite for energy has led scientists to attempt harnessing nuclear fusion, the power inherent to the sun and other stars. Now, a new study from Princeton physicists found a method that can aid the safe creation of fusion on Earth, potentially leading to a limitless supply of electricity.
Fusion reactors work by combining light elements like hydrogen into plasma – a superhot and charged state of matter. During the fusion process, two lighter atomic nuclei are combined into a heavier nucleus, releasing energy.
The resulting plasma can be employed into generating a tremendous amount of energy but the fusion facilities, called tokamaks, face the hard task of trying to keep impurities out of reactions. These can lower the efficiency of the fusion, while the goal of the scientists is to keep the plasma as hot as it can be, actually ten times hotter than the sun's core. This maximizes fusion reactions and leads to the creation of the greatest amount of electricity.
What scientists from the Princeton Plasma Physics Laboratory (PPPL) discovered is a way to inject boron powder into plasma, allowing for greater control, lowering greenhouse gases, and getting rid of long-term radioactive waste.
PPPL physicist Robert Lunsford was the lead author of the paper, published in Nuclear Fusion, that outlined the accomplishment.
"The main goal of the experiment was to see if we could lay down a layer of boron using a powder injector," said Lunsford in a press release. "So far, the experiment appears to have been successful."
Michio Kaku: Energies of the Future
The method devised by Lunsford and his team uses boron to prevent tungsten in tokamak walls from interacting with the plasma. The tungsten can cause the plasma particles to cool, lowering reaction efficiency. The so-called boronization of surfaces that face the plasma is easier to accomplish with the powder, as it's something that can be done while the machine is already running. This can allow the fusion device to be an uninterrupted source of energy. "This is one way to get to a steady-state fusion machine," remarked Lunsford.
The powder method is also cheaper and less dangerous than the current practice of injecting potentially explosive diborane gas into the plasma.
The scientists envision further investigating the uses of boron powder, optimistic that this approach can allow them to understand the behavior of plasma in unprecedented depth.
PPPL physicist Robert Lunsford.
CREDIT: Elle Starkman / PPPL Office of Communications