While Proxima Centauri’s flaring activity is well known to astronomers using visible wavelengths, new observations on Atacama’s massive millimeter/sub-millimeter arrays (ALMAs) highlight the extreme activity of stars at radio and millimeter wavelengths.
The concept of violent star flare artists from Proxima Centauri. Image credit: S. Dagnello, nrao/aui/nsf.
Proxima Centauri is a red star, about 4.24 light years away from the constellation of Centaurus.
Discovered in 1915 by Scottish astronomer Robert Innes, the star is invisible to the naked eye.
Its average luminosity is very low, very small compared to other stars, only about one eighth of the mass of the sun.
Proxima Centauri is also known as the Alpha Centauri C, as it is actually part of the Triple Star system.
The separation of the stars from their larger companions, Alpha Centauri A and B, is about 0.2 light-years, equivalent to 400 times the orbit of Neptune.
Proxima Centauri hosts the terrestrial exoplanet Proxima B in a habitable zone of 0.0485 Au.
The stars are well-established as highly active stars and are the primary targets for investigating the effects of star activity on the habitability of planets orbiting Red War.
In the new study, astronomer Kiana Burton at the University of Colorado and astronomer Meredith McGregor at Johns Hopkins University, and colleagues used archival data and new Alma observations to study millimeter-wavelength flare activity.
The small size and strong magnetic field of the Proxima Centauri show that its entire internal structure is convection (unlike the sun, which has both convective and non-reliable layers).
The magnetic field will twist and develop tension, and eventually snap, sending energy and particle flow outwards to what is observed as flares.
“Our solar activity does not remove the Earth’s atmosphere and instead creates beautiful auroras because it has a thick atmosphere and a strong magnetic field to protect the planets,” Dr. McGregor said.
“But we know that Proxima Centauri’s flares are much stronger and there are rocky planets in their habitable zones.”
“What are these flares doing to their atmosphere? Are there any large fluxes of radiation and particles that are chemically altered or perhaps completely eroding at the atmosphere?”
This study represents the first multi-wavelength study using millimeter observations to reveal a new appearance in flare physics.
A total of 463 flare events were reported with 50 hours of ALMA observations using both the full 12-meter array and the 7-M Atacama Compact Array (ACA).twenty four On 1027 ERG, and a short period of 3-16 seconds.
“When you see the flare with Alma, you see electromagnetic radiation, that is, light of various wavelengths,” Dr. McGregor said.
“But this radio-wavelength flaring also gives us a way to track the properties of those particles and understand what is free from the stars.”
To this end, astronomers characterized the stars (so-called flare frequency distribution) and mapped the number of flares as a function of energy.
Typically, the gradient of this distribution tends to follow the power law function. More frequent (lower energy) flares occur more frequently, but larger, more energy flares do not occur regularly.
Proxima Centauri experiences so many flares, researchers have detected many flares within each energy range.
Furthermore, they were able to quantify the asymmetry of the highest energy flares of stars, explaining how the attenuation phase of the flare is much longer than the initial burst phase.
Radio and millimeter wavelength observations help to constrain the energy associated with these flares and their associated particles.
“Millimeter flares look much more frequent,” Dr. McGregor said.
“It’s a different power law than what you see at optical wavelengths.”
“Looking only at the optical wavelengths is missing important information.”
“The Alma is the only millimeter interferometer that is sensitive enough to these measurements.”
Team’s Survey results It was published in Astrophysical Journal.
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Kiana Burton et al. 2025. Proxima Centauri Campaign – First constraint on millimeter flare rate from Alma. APJ 982, 43; doi:10.3847/1538-4357/ada5f2
Source: www.sci.news
