̽��ֱ�� of Cambridge - solar flare

Astronomers uncover risks to planets that could host life

sc604 — Mon, 05 Aug 2024 14:10:39 +0000

̽��ֱ��discovery suggests that the intense UV radiation from these flares could significantly impact whether planets around red dwarf stars can be habitable.

“Few stars have been thought to generate enough UV radiation through flares to impact planet habitability. Our findings show that many more stars may have this capability,” said first author Vera Berger, who led the research while based at the ̽��ֱ�� of Hawai’i and who is now based at the ̽��ֱ�� of Cambridge.

Berger and her team used archival data from the GALEX space telescope to search for flares among 300,000 nearby stars. GALEX is a now-decommissioned NASA mission that simultaneously observed most of the sky at near-and far-UV wavelengths from 2003 to 2013. Using new computational techniques, the team mined insights from the data.

“Combining modern computer power with gigabytes of decades-old observations allowed us to search for flares on thousands and thousands of nearby stars,” said co-author Dr Michael Tucker from Ohio State ̽��ֱ��.

According to researchers, UV radiation from stellar flares can either erode planetary atmospheres, threatening their potential to support life, or contribute to the formation of RNA building blocks, which are essential for the creation of life.

̽��ֱ��study, published in the Monthly Notices of the Royal Astronomical Society, challenges existing models of stellar flares and exoplanet habitability, showing that far-UV emission from flares is on average three times more energetic than typically assumed, and can reach up to twelve times the expected energy levels.

“A change of three is the same as the difference in UV in the summer from Anchorage, Alaska to Honolulu, where unprotected skin can get a sunburn in less than 10 minutes,” said co-author Benjamin J. Shappee from the ̽��ֱ�� of Hawai’i.

̽��ֱ��exact cause of this stronger far-UV emission remains unclear. ̽��ֱ��team believes it might be that flare radiation is concentrated at specific wavelengths, indicating the presence of atoms like carbon and nitrogen.

“This study has changed the picture of the environments around stars less massive than our Sun, which emit very little UV light outside of flares,” said co-author Jason Hinkle.

According to Berger, now a Churchill Scholar at Cambridge, more data from space telescopes is needed to study the UV light from stars, which is crucial for understanding the source of this emission.

“Our work puts a spotlight on the need for further exploration into the effects of stellar flares on exoplanetary environments,” said Berger. “Using space telescopes to obtain UV spectra of stars will be crucial for better understanding the origins of this emission.”

Reference:
Vera L Berger et al. ‘Stellar flares are far-ultraviolet luminous.’ Monthly Notices of the Royal Astronomical Society (2024). DOI: 10.1093/mnras/stae1648

Adapted from a ̽��ֱ�� of Hawai’i media release.

Astronomers have discovered that red dwarf stars can produce stellar flares that carry far-ultraviolet (far-UV) radiation levels much higher than previously believed.

Scott Wiessinger/NASA

A red dwarf star unleashes a series of powerful flares.

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Solar storms could cost USA tens of billions of dollars

Anonymous — Thu, 19 Jan 2017 14:42:18 +0000

Previous studies have focused on direct economic costs within the blackout zone, failing to take account of indirect domestic and international supply chain loss from extreme space weather.

According to the study, published in the journal Space Weather, on average the direct economic cost incurred from disruption to electricity represents just under a half of the total potential macroeconomic cost.

̽��ֱ��paper was co-authored by researchers from the Cambridge Centre for Risk Studies at ̽��ֱ�� of Cambridge Judge Business School, British Antarctic Survey, the British Geological Survey and the ̽��ֱ�� of Cape Town.

Under the study’s most extreme blackout scenario, affecting two-thirds of the US population, the daily domestic economic loss could total $41.5 billion plus an additional $7 billion loss through the international supply chain.

Electrical engineering experts are divided on the possible severity of blackouts caused by “Coronal Mass Ejections,” or magnetic solar fields ejected during solar flares and other eruptions. Some believe that outages would last only hours or a few days because electrical collapse of the transmission system would protect electricity generating facilities, while others fear blackouts could last weeks or months because those transmission networks could in fact be knocked out and need replacement.

Extreme space weather events occur often, but only sometimes affecting Earth. ̽��ֱ��best-known geomagnetic storm affected Quebec in 1989, sparking the electrical collapse of the Hydro-Quebec power grid and causing a widespread blackout for about nine hours.

There was a very severe solar storm in 1859 known as the “Carrington event” (after the name of a British astronomer). A widely cited 2012 study by Pete Riley of Predictive Sciences Inc. said that the probability of another Carrington event occurring within the next decade is around 12 per cent; a 2013 report by insurer Lloyd’s, produced in collaboration with Atmospheric and Environmental Research, said that while the probability of an extreme solar storm is “relatively low at any given time, it is almost inevitable that one will occur eventually.”

“We felt it was important to look at how extreme space weather may affect domestic US production in various economic sectors, including manufacturing, government and finance, as well as the potential economic loss in other nations owing to supply chain linkages,” says study co-author Dr Edward Oughton of the Cambridge Centre for Risk Studies.

“It was surprising that there had been a lack of transparent research into these direct and indirect costs, given the uncertainty surrounding the vulnerability of electrical infrastructure to solar incidents.”

̽��ֱ��study looks at three geographical scenarios for blackouts caused by extreme space weather, depending on the latitudes affected by different types of incidents.

If only extreme northern states are affected, with 8 per cent of the US population, the economic loss per day could reach $6.2 billion supplemented by an international supply chain loss of $0.8 billion. A scenario affecting 23 per cent of the population could have a daily cost of $16.5 billion plus $2.2 billion internationally, while a scenario affecting 44 per cent of the population could have a daily cost of $37.7 billion in the US plus $4.8 billion globally.

Manufacturing is the US economic sector most affected by those solar-induced blackouts, followed by government, finance and insurance, and property. Outside of the US, China would be most affected by the indirect cost of such US blackouts, followed by Canada and Mexico as these countries provide a greater proportion of raw materials, and intermediate goods and services, used in production by US firms.

Reference
Oughton, EJ et al. Quantifying the daily economic impact of extreme space weather due to failure in electricity transmission infrastructure. Space Weather; 18 Jan 2017; DOI: 10.1002/2016SW001491

Adapted from a press release by the Cambridge Judge Business School.

̽��ֱ��daily economic cost to the USA from solar storm-induced electricity blackouts could be in the tens of billions of dollars, with more than half the loss from indirect costs outside the blackout zone, according to a new study led by ̽��ֱ�� of Cambridge researchers.

NASA Goddard Space Flight Center

Magnificent CME Erupts on the Sun - August 31

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A new twist on soap films

sc604 — Fri, 23 May 2014 15:13:03 +0000

̽��ֱ��way in which soap films collapse and re-form when twisted or stretched could hold the key to predicting the formation and location of mathematical singularities, which can be seen in the motion of solar flares and other natural phenomena.

Research on the processes by which soap films undergo transitions from one stable state to another has led to conjectures on the nature and location of the singular events that occur during the change of form, connecting two previously separate areas in mathematics.

In mathematics, singularities occur when an equation or surface breaks down and ‘explodes’. In surfaces such as soap films, singularities occur when the surface collides with itself, changing shape in the blink of an eye.

Researchers from the ̽��ֱ�� of Cambridge have shown that identifying a special type of curve on the surface can help predict where these singularities are likely to occur in soap films, which could in turn aid in the understanding of singularities in the natural world. ̽��ֱ��results are published in the journal Proceedings of the National Academy of Sciences (PNAS).

We are all familiar with the simplest soap films, which are formed by dipping a wire loop into a soap solution: the flat surface that spans the wire and the bubbles which are formed when we blow on the film. With suitably shaped wires however, much more complex structures can be formed, such as Möbius strips.

All static soap films are ‘minimal surfaces’, for they have the least area of all possible surfaces that span a given wire frame.

What is less understood are the dynamic processes which occur when a minimal surface like a soap film is made unstable by deforming the supporting wire. ̽��ֱ��film typically moves in a fraction of a second to a new configuration through a singular point, at which the surface collides with itself and changes its connectivity.

These kinds of violent events also occur in the natural world – in fluid turbulence and in the motion of solar flares emanating from the sun – and one of the great challenges has been to predict where they will occur.

In research supported by the EPSRC, a team from the Department of Applied Mathematics and Theoretical Physics attempted to understand how to predict where the singularity will occur when soap films are twisted or stretched to a point of instability. For example, it is well-known that the surface spanning two separate wire loops will collapse to a singularity in between the loops.

In previous work, the group had shown that Möbius strip singularity occurs not between the loops but at the wire frame, where there is a complex rearrangement of the surface. “What was unclear was whether there was an underlying mathematical principle by which this striking difference could be explained,” said Professor Raymond Goldstein, who collaborated with Dr Adriana Pesci, Professor Keith Moffatt, and James McTavish, a maths undergraduate, on the research.

̽��ֱ��team recognised that a geometric concept known as a systole might be the key to understanding where singularities will occur. A systole is the length of the shortest closed curve on surface that cannot be shrunk to a point while remaining on the surface. An example of this is found on a bagel, where the shortest such curve encircles the bagel like a handle. Mathematicians have studied the geometric properties of these curves in recent decades, establishing constraints on the relationship between the length of a systole and the area of the surface on which they lie.

Using new laboratory experiments and computations, the researchers found evidence that the ultimate location of the singularities that occur when soap films collapse can be deduced from the properties of the systole. If the systolic curve loops around the wire frame, then the singularity occurs at the boundary, while if there is no such linking the singularity occurs in the bulk.

“This is an example of experimental mathematics, in the sense that we are using laboratory studies to inform conjectures on mathematical connections,” said Professor Goldstein. “While they are certainly not rigorous, we hope they will stimulate further research into this new, developing area.”

Soap films with complex shapes shed light on the formation of mathematical singularities, which occur in a broad range of fields.

This is an example of experimental mathematics, in the sense that we are using laboratory studies to inform conjectures on mathematical connections

Raymond Goldstein

Singularity in a soap film

Raymond Goldstein

Soap film singularity

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New light shed on explosive solar activity

lw355 — Mon, 02 Jul 2012 10:00:34 +0000

̽��ֱ��study published today by ̽��ֱ�� of Cambridge scientists working with colleagues in India and the USA is the first to visualise the movement of gases at one million degrees in coronal loops – solar structures that are rooted at both ends and extend out from active regions of the Sun. Active regions are the ‘cradle’ for explosive energy releases such as solar flares and coronal mass ejections (CMEs).

̽��ֱ��observation will help scientists understand what is considered to be one of the most challenging issues in astrophysics – how solar structures are heated and maintained in the upper solar atmosphere. Extreme solar activity can lead to severe space storms that interfere with satellite communications and damage electric power transmission grids on Earth. Solar activity is cyclical, with the next maximum forecast to occur around May 2013, and severe space weather is now listed very high on the UK’s 2012 National Risk Register of Civil Emergencies.

Based on observations from the Hinode satellite (a joint Japanese, NASA, European Space Agency and UK project), the new findings provide the first evidence of plasma upflows travelling at around 20 km per second in the one million degree active region loops. ̽��ֱ��scientists suggest that the upflow of gases is probably the result of “impulsive heating” close to the footpoint regions of the loops.

“Active regions are now occurring frequently across the Sun. We have a really great opportunity to study them with solar spacecraft, such as Hinode and the Solar Dynamics Observatory (SDO),” said co-author Dr Helen Mason from the ̽��ֱ�� of Cambridge’s Department of Applied Mathematics and Theoretical Physics. “Probing the heating of the Sun's active region loops can help us to better understand the physical mechanisms for more energetic events which can impinge on the Earth’s environment.”

Previous ultraviolet images of the Sun taken by NASA’s SDO have shown large loops of hot gas guided by the Sun’s magnetic field and rooted near sunspots. Despite such remarkable developments in the observations and theory of active regions over the past few decades, the question remained as to how solar plasma is heated and rises up into the loops in the first place.

Now, the new research provides the first visualisation of plasma flow by showing the movement of gases within the loop as ‘blueshifts’ in diagnostic images using the extreme ultraviolet imaging spectrometer (EIS) on the Hinode satellite. Spectral lines produced by the spectrometer act like ‘fingerprints’ or the ‘bar code’ in a supermarket – the lines identify the multitude of elements and ions within the loop and shifts in the position of the lines provide information on the motion of the plasma. Although the Sun is composed mainly of hydrogen and helium, there are also other trace elements, such as oxygen and iron, in the hot ionised gas within the loops.

̽��ֱ��scientists suggest that the gas movement is caused by a process of “chromospheric evaporation” in which “impulsive heating” on a small scale can result in the heating of the solar active regions but on a larger scale can lead to huge explosions, such as solar flares or coronal mass ejections.

“It is believed that magnetic energy builds up in an active region as the magnetic field becomes distorted, for example by motions below the surface of the Sun dragging the magnetic fields around,” explained Mason, whose research is partially funded by the UK’s Science and Technology Facilities Council (STFC). “Sometimes magnetic flux can emerge or submerge and affect the overlying magnetic field. We believe that solar plasma surges upwards when impulsive heating results from magnetic reconnection which occurs either in the loops or close to the Sun’s surface. These disruptions are sometimes relatively gentle but can also be catastrophic.”

Commenting on the newly published study, Professor Richard Harrison MBE, Head of Space Physics and Chief Scientist at the STFC Rutherford Appleton Laboratory, said: “ ̽��ֱ��Sun governs the environment in which we live and it is the so-called solar active regions that drive extreme conditions leading to the explosive flares and the huge eruptions; understanding these active regions is absolutely critical for the study of what we now call space weather. ̽��ֱ��work published by in this paper is a key element of that work, applying innovative analyses to the observations from the UK-led Hinode/EIS instrument.”

̽��ֱ��researchers hope that a better understanding of active regions might one day help scientists to identify the magnetic field structures that lead to explosive solar energy releases and use this as a means for predicting when such events will occur.

̽��ֱ��study is published today in Astrophysical Journal Letters.

̽��ֱ��first images of an upward surge of the Sun’s gases into quiescent coronal loops have been identified by an international team of scientists. ̽��ֱ��discovery is one more step towards understanding the origins of extreme space storms, which can destroy satellite communications and damage power grids on Earth.

Probing the heating of the Sun's active region loops can help us to better understand the physical mechanisms for more energetic events which can impinge on the Earth’s environment.

Dr Helen Mason

SDO/AIA (NASA)

Sun's active region loops

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