by Our sun is famous for its occasional flashes of energy known as solar flares, which cause space weather that can disrupt communications and power infrastructure here on Earth.
But we should really be thankful that we’re not around a star that erupts with so-called “superflares” that can be 100 to 10,000 times more energetic than even the most powerful solar flares. A flare from the sun could be catastrophic for Earth, which would seriously damage our planet’s atmosphere and the life forms that depend on it. Fortunately, superflares can be seen around stars so far away that they are just points of light in the sky from our perspective.
Astronomers see these energetic flares as a sudden and extreme manifestation of the distant stars, and this has given scientists the chance to play detective in a quest to find out why certain stars explode so violently.
Related: Scientists study violent ‘superflares’ on stars thousands of times brighter than the sun
And now, a team of researchers from the Mackenzie Center for Radio Astronomy and Astrophysics at the Mackenzie Presbyterian University in Brazil and the School of Physics and Astronomy at the University of Glasgow in the UK have looked at the two suspects most widely believed to be responsible. superflares.
To do this, they analyzed 37 superflares seen in the binary star system Kepler-411 as well as five more coming from the star Kepler-396.
Interrogating two superflare suspects
A stellar flare is thought to occur when magnetic energy built up in a star’s atmosphere is suddenly released as a result of magnetic field lines “snapping” and “reconnecting.” This is probably true for any type of stellar flare. So, despite the fact that there are power differences between solar flares from the sun and stellar flares from elsewhere in the cosmos, the study team was able to use the mechanism that sends flares from our star to distant flares and more considered energetic. .
The researchers were also able to apply the vast amount of data collected on solar flares since they were first described in the scientific literature by astronomers Richard Carrington and Richard Hodgson, who independently observed the same solar flare on 1 September, 1859.
“Since then, solar flares have been observed with intense brightness lasting seconds to hours and at different wavelengths, from radio waves and visible light to ultraviolet and X-rays,” Alexandre Araújo, study team member and Ph.D. candidate at the Mackenzie Center for Radio Astronomy, said in a statement.
The team also had data on stellar flares from observations of other stars by observatories designed to look for signs of orbiting planets, such as the Kepler Space Telescope and the Transiting Exoplanet Survey Satellite (TSES).
The “usual suspect” model for these violent superflares sees the radiation from an outburst treated as “blackbody emission,” referring to electromagnetic radiation that is in equilibrium with its environment. Such emissions also cover a wide spectrum of wavelengths and depend on the temperature of the emitting body. The “blackbody emission,” in the case of the superflares studied, would have a temperature of about 17,500 degrees Fahrenheit (9,700 degrees Celsius).
But, there are other suspicions out there that cannot be ruled out. This alternative model sees superfluids generated as a result of hydrogen atoms being stripped of electrons, or getting “ionized”, then recombining with these electrons to form neutral hydrogen atoms once more. The team’s analysis favors this external model as an explanation for supershells.
“Given the known energy transfer processes in flares, we argue that the hydrogen recombination model is physically more plausible than the blackbody model to explain the origin of broadband optical emission from flares,” Paulo Simões, professor at Mackenzie Presbyterian University who led . the new study, said in a statement. “We conclude that the estimates for the total flare energy based on the hydrogen recombination model are about an order of magnitude lower than the values obtained using the blackbody radiation model and are a better fit to the flare processes that is known.”
Simões also said that the limitation of the first and most popular black body model is related to energy transport. A certain amount of energy is required to exist in the star’s photosphere to ensure that the plasma in the region is heated up enough to produce the extreme brightness associated with supernovae. However, none of the commonly accepted energy transport mechanisms for solar flares have the ability to explain how this level and distribution of energy can be achieved.
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“Calculations first performed in the 1970s and later confirmed by computer simulations show that most electrons accelerated in solar flares fail to cross the chromosphere. [the sun’s outer atmosphere] and enter the photosphere,” Araújo said.
The team argues that the hydrogen recombination radiation model, on the other hand, is more physically consistent. The team admitted that the unfortunate aspect of all of this, however, is the hydrogen reconnection model and its link to superblows cannot yet be confirmed by observation.
Still, the researchers conclude that their research, at least, provides a strong argument in favor of the hydrogen reconnection model, which they say has been neglected in most superflare studies so far.
The team’s research was published earlier this year in the journal The Monthly Notices of the Royal Astronomical Society.
