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Proxima Centauri exhibits intense flare activity and recent Alma observations reveal new insights

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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

Proxima B’s Explosive Cryovolcano and Habitable Subsurface Ocean

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Astronomers at NASA and the University of Washington estimated the total internal heating rate and depth to potential subsurface oceans for 17 potentially cold ocean planets. These planets are low-mass exoplanets with surface temperatures and densities consistent with icy surfaces and large amounts of water. content. Like the icy moons of our solar system, these planets could be astrobiologically important worlds with habitable environments beneath their icy surfaces.

This artist’s impression shows Proxima b orbiting Proxima Centauri, the closest star to our solar system at just 4.23 light years. The double star Alpha Centauri AB also appears in the image between the exoplanet and Proxima itself. Image credit: M. Kornmesser / ESO.

Ocean planets have been proposed as a class of low-density terrestrial exoplanets with significant liquid water layers.

They exist in different climatic states, including ice-free, partially ice-covered, and completely frozen surfaces.

“Our analysis suggests that the surfaces of these 17 alien worlds may be covered in ice, but they are affected by internal heating due to the decay of radioactive elements and tidal forces from their host stars,” said NASA Goddard researcher Dr. Lynne Quick. “We predict that it will receive enough water to maintain its internal ocean.” Space flight center.

“Due to the amount of internal heating the planets experience, all the planets in our study may also exhibit polar volcanic eruptions in the form of geyser-like plumes.”

Dr. Quick and his colleagues examined the status of 17 confirmed exoplanets. These planets are roughly Earth-sized but less dense, suggesting they may have significant amounts of ice and water instead of dense rock.

Although the exact composition of these planets remains unknown, all initial estimates of surface temperatures from previous studies indicate that they are much cooler than Earth, and their surfaces may be covered with ice. This suggests that there is a possibility that

The authors improved their estimates of each exoplanet’s surface temperature by recalculating them using the known surface brightness and other properties of Europa and Enceladus as models.

They also estimated the total internal heating of these exoplanets by using the shape of each exoplanet’s orbit to capture the heat generated from the tides and adding it to the heat expected from radioactive activity. did.

Because oceans cool and freeze at the surface while being heated from within, estimates of surface temperature and total heating provide information about the thickness of each exoplanet’s ice layer.

Finally, they compared these numbers to Europa’s and used Europa’s estimated level of geyser activity as a conservative baseline for estimating the exoplanet’s geyser activity.

They predict surface temperatures will be up to 33 degrees Celsius (60 degrees Fahrenheit) cooler than previous estimates.

Artist’s impression of the planetary system LHS 1140. Image credit: Sci.News.

Estimated ice shell thicknesses ranged from approximately 58 m (190 ft) for Proxima b and 1.6 km (1 mi) for LHS 1140b to 38.6 km (24 mi) for LHS 1140b. MOA-2007-BLG-192Lbcompared to an estimated European average of 29 km (18 mi).

The estimated geyser activity was only 8 kg/s for Kepler 441b, 2,000 kg/s for Europa, 290,000 kg/s for LHS 1140b, and 6 million kg/s for Proxima b.

“Our models predict that oceans could be found relatively close to the surfaces of Proxima b and LHS 1140b, and that geyser activity rates could exceed those of Europa by hundreds to thousands of times. “The telescope has the best chance of detecting geological activity on these planets because of their presence,” said Dr. Quick.

“This activity can be seen when an exoplanet passes in front of its star. Certain colors of the star’s light can be dimmed or blocked by water vapor from geysers. there is.”

“If water vapor is detected sporadically and the amount of water vapor detected changes over time, it would suggest the presence of a cryovolcanic eruption.”

“Water may contain other elements and compounds, which could reveal whether it can support life.”

“Elements and compounds absorb light of certain characteristic colors, so analysis of starlight allows scientists to determine the composition of geysers and assess the potential habitability of exoplanets. Become.”

a paper Regarding the survey results, astrophysical journal.

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Lynne C. Quick other. 2023. Prospects for polar volcanic activity on cold ocean planets. APJ 956, 29; doi: 10.3847/1538-4357/ace9b6

Source: www.sci.news