A team of scientists has witnessed one of the most powerful stellar flares ever seen in a double star system discovered in the constellation Orion.
Dubbed a "superflare," the massive blast of stellar radiation releases 10 times more mass than any flare ever emanating from the Sun, according to new research published in The Astrophysical Journal.
While the mechanism behind these monstrous flares is still not well understood, the new research indicates that superplanets arise from highly magnetically active stars.
The study authors wrote that these superplanets may be accompanied by massive explosions of charged particles that could destroy life on any planets in their firing line. (Fortunately for us, Earth is not one of those planets.)
In their new research, the astronomers targeted a star system called V1355 Orionis (or HD 291095), which is about 400 light-years from Earth and features two stars orbiting each other.
They belong to a class of stars known to harbor many sunspots - dark, planet-sized regions formed as a result of intense electromagnetic activity - that have been linked to other observed superflares.
In general, stellar flares occur when magnetic field lines in a star's atmosphere intertwine, capture and reconnect, causingA powerful emission of radiation that can be seen across the entire electromagnetic spectrum.
In the Sun, flares may be accompanied by towering rings of plasma, known as prominences, that can rise tens of thousands of miles above the Sun's surface. If this solar plasma is released fast enough, it can break free from the sun and become a coronal mass ejection (CME), a massive mass of high-energy particles that can knock satellites out of orbit if our planet happens to be in their path.
By combining observations from NASA's Transiting Exoplanet Survey Satellite (TESS) and the Seimei telescope in Japan, scientists studied the distant star system in multiple wavelengths of light to capture the most complete picture possible of the superflare's evolution.
They found that the flare began with one of the most powerful stellar explosions ever - a high-velocity prominence erupting from a star at more than 2.2 million miles per hour (3.5 million km/h).
This explosion, the authors write, far exceeded the star's escape velocity, shooting trillions of tonnes of electrically charged matter outward in what may be one of the largest masses ever observed.
It's not certain exactly how these large, powerful coronal mass ejections will affect life on any unlucky planets that cross their path, but scientists said the effects would be far more catastrophic than those associated with the worst coronal mass ejections to ever hit Earth.
Ultimately, the discovery of this massive flare is not so much a warning to our own planet as it is to the search for life on other worlds: Planets around magnetically hyperstellar systems such as V1355 Orionis may not be the best places to look.
A study may reveal the origin of an asteroid "found orbiting Earth" : Kamo'oalewa
The moon dominates our view of the night sky, but it's not the only thing orbiting Earth. A few of what scientists call quasars also orbit our planet.
One of them is called Kamo'oalewa, a near-Earth asteroid. It is similar to the Moon in some respects. Could it be a piece of the moon?
Kamo'oalewa was discovered in 2016 with Pan-STARRS at Haleakala Observatory. It is an unusual object because its orbit changes over time. But as it changes, it always stays close to the ground.
Its surface reflects light in the same way as the Moon, thanks to the presence of silicates. This is an interesting clue to its origins, but it is not the only one. While Kamo'oalewa is not the only quasi-moon, nor the only one in the Apollo group, it is the smallest, closest and most stable.
A new study is examining the object's orbit to see if it could have been ejected from the moon. The study comes from orbital tracks of the Lunar-Ejecta origin of the near-Earth asteroid Kamo`oalewa. First author Jose Daniel Castro Cisneros of the University of Arizona's Department of Physics is participating in the study.
Sometimes, small bodies in the solar system do not follow sun-centered orbits. Instead, due to orbital resonance, it can co-orbit a huge planet. These are called the common orbital bodies.
There are three main types of co-orbitals: Trojan/tadpole (T), horseshoe (HS), and satellite/quasi-satellite (QS). The two important types in this research are: HS and QS.
Kamo'oalewa lies outside Earth's Hill Sphere, a region of space that attracts moons. The Moon is located within the Hill Sphere, and although its orbit undergoes small perturbations and changes, it is fairly stable. But Kamo'oalewa is outside a sphere and its orbit is very elliptical. It is called a semi-moon because the sun exerts more power on it than on the earth.
The Earth has 21 objects in common orbit: two are Trojans, six are in QS state, and 13 are subject to HS motion. But Kamo'oalewa is different from other QS beings.
And Kamo'oalewa switches back and forth between the HS movement and the QS movement and has done so for centuries. And it will continue to do so for centuries.
The paper states: "Given its Earth-like orbit and its physical similarity to lunar surface materials, we explore the hypothesis that it may have originated as a piece of debris from a meteorite impact on the lunar surface."
Since they can't go back in time and watch the Moon during its long history of bombardment, scientists do the next best thing. They use computers to simulate events with a variety of variable values and see what they find. In this paper, the researchers modeled particles ejected from the moon by collisions.
"We perform a numerical simulation of the dynamic evolution of particles ejected from different locations on the lunar surface with a range of ejection velocities," they wrote.
Most of the particles in their simulations leave the circumference of the Earth and the Moon and move to orbits around the Sun, which is not surprising. The sun's dominant mass affects everything in the solar system.
But some - only a small number - do not enter sun-centered orbits. Instead, it takes orbits similar to Kamo'oalewa's. "As these projectiles escape from the Earth-Moon environment and evolve into heliocentric orbits, we find that a small fraction of the launch conditions produce results consistent with the dynamic behavior of Kamo'oalewa," they wrote. And those of Earth's smallest and most stable quasi-moon have one thing in common: launch speed. "The most favorable conditions are launch velocities slightly greater than the escape velocity of the trailing lunar hemisphere," the researchers explained.
"The results show that the Kamo'oalewa tilt could have been triggered from a smaller initial tilt by movements on approach during HS," the researchers explain.
The historical record preserved in lunar craters provides a good test of the Kamo'oalewa lunar impact hypothesis.
The researchers wrote: "It appears that the velocities of lunar projectiles (in excess of the lunar escape velocity, 2.4 km/s) needed to obtain co-orbital results can be achieved in meteor impacts on the Moon, which have routine impact velocities of 22 km/s (13.7 miles). /sec) and can reach 55 km/sec.
Other simulation studies show that impacts at these speeds can spew debris traveling at 6 km/s, well above the escape threshold of 2.4 km/s.
Studies of lunar craters also show that large impact craters with a diameter of more than 33 km occur once every 25 million years, and these large craters are likely to be a source of impact projectiles that travel fast enough to escape from the moon.
Researchers say the crater that might be the source of Kamo'oalewa remains to be determined.
"We leave for a separate study to investigate whether a lunar crater of proportional size, age, and geographic location could be compatible with the hypothesis of lunar ejection as the source of Kamo'oalewa," they wrote.
And if scientists can prove that Kamo'oalewa is part of the moon, that opens up some interesting possibilities.
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