Whimpers from the Sun?

May 11, 2005
Whimpers from the Sun?

Solar physicists have observed the smallest ever coronal mass ejection (CME) - a type of explosion where plasma from the Sun is thrown out into space, sometimes striking the Earth and damaging orbiting satellites. The observation has come as a great surprise to scientists and has turned previous ideas up-side-down.

Image: A negative image of the Sun showing the active region was taken from Yohkoh data and is provided courtesy of the Solar UK Research Facility. Click on the image to obtain a high resolution version.

To date studies of these phenomena have focussed on large explosions which are easier to detect and which have massive footprints on the Sun, sometimes covering thousands of millions of square miles. But in a paper published in the May edition of Astronomy and Astrophysics, an international team from the UK, Argentina, Finland, France and Hungary showed that CMEs can also be produced from regions as small as the Earth, around 10,000 miles across. This still may sound large but it is tiny by cosmic standards.

CMEs are believed to be caused by the destabilisation of twisted loops in the Sun's magnetic field, which contain lots of energy, settling into more stable positions (like a twisted rubber band unwinding suddenly). Until now, the events have been traced back to large areas of magnetic activity on the Sun, but the new observations relate to an area much smaller than anything seen before. However, even though the event was small it was still energetic enough to reach the Earth and amazingly the magnetic field lines were ten times more twisted than is usually seen in the larger areas.

Understanding CMEs and the mechanisms that power them is important because the plasma and accelerated particles they throw into space can damage satellites, cause harm to astronauts and even affect the Earth itself, causing beautiful aurora but also power black outs and problems to radio signals. This is the science of space weather.

Dr Lucie Green of UCL's Mullard Space Science Laboratory said "Previously coronal mass ejections were thought to be huge, involving massive portions of the Sun's magnetic field and all the theoretical models are based around this assumption. However, this one was amazing in that it came from a tiny magnetic region on the Sun which would normally have been overlooked in the search for CME source regions. This will be an exciting area for further study."

Existing models for CMEs are based on the type of large event previously observed and the team cannot yet say how frequent such mini CMEs are or whether they represent a significant part of space weather. The event was so small that is was almost at the limit of what we can see with current instruments. Future missions studying the Sun will be able to 'see' in much better detail, such as the UK-US-Japanese mission called Solar-B.

The research used data from NASA/ESA's SOHO spacecraft, NASA's TRACE satellite and from the now defunct Japanese/US/UK Yohkoh satellite. UK involvement was funded by PPARC.

The paper appeared in the May edition of the Astronomy and Astrophysics Journal.

Source: PPARC

Explore further: New discovery Proxima b is in host star's habitable zone—but could it really be habitable?

Related Stories

The proliferation of Jupiter-like worlds

August 29, 2016

Our galaxy is home to a bewildering variety of Jupiter-like worlds: hot ones, cold ones, giant versions of our own giant, pint-sized pretenders only half as big around.

IRIS spots plasma rain on sun's surface

August 8, 2016

On July 24, 2016, NASA's Interface Region Imaging Spectrograph, or IRIS, captured a mid-level solar flare: a sudden flash of bright light on the solar limb – the horizon of the sun – as seen at the beginning of this video. ...

Getting to know more about sun storms

August 10, 2016

A violent solar eruption can disrupt the Earth's magnetic field, which in turn can interfere with power grids. In Washington, the White House is making contingency plans – as is the electrical power sector in Norway.

1967 solar storm nearly took US to brink of war

August 9, 2016

A solar storm that jammed radar and radio communications at the height of the Cold War could have led to a disastrous military conflict if not for the U.S. Air Force's budding efforts to monitor the sun's activity, a new ...

Image: Majestic solar eruption larger than Earth

August 1, 2016

A gigantic ribbon of hot gas bursts upwards from the Sun, guided by a giant loop of invisible magnetism. This remarkable image was captured on 27 July 1999 by SOHO, the Solar and Heliospheric Observatory. Earth is superimposed ...

Recommended for you

Smarter brains are blood-thirsty brains

August 30, 2016

A University of Adelaide-led project has overturned the theory that the evolution of human intelligence was simply related to the size of the brain—but rather linked more closely to the supply of blood to the brain.

Theorists solve a long-standing fundamental problem

August 30, 2016

Trying to understand a system of atoms is like herding gnats - the individual atoms are never at rest and are constantly moving and interacting. When it comes to trying to model the properties and behavior of these kinds ...

Reconstructing the sixth century plague from a victim

August 30, 2016

Before the infamous Black Death, the first great plague epidemic was the Justinian plague, which, over the course of two centuries, wiped out up to an estimated 50 million (15 percent) of the world's population throughout ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.