Researchers at the University of Central Lancashire have monitored the birth of a sunspot over a period of eight hours using observations from NASA's Solar Dynamics Observatory (SDO). Dr Stephane Regnier will present the results at the RAS National Astronomy Meeting in Llandudno on Monday 18th April.
The emerging sunspot was first detectable at 17:00 UT on 30th May 2010 in SDO magnetograms, which map the magnetic intensity of the solar disc. The first signs were small patches of strong positive and negative magnetic field, separated by around 7 000 km.
"About 5 hours after the first signs of the eruption, the magnetic disturbance had grown to around 20 000 km across and we could see a pore form in the visible wavelength images next to the negative polarity." said Regnier. "By 18:00 UT on June 1st, the sunspots had appeared."
The photosphere is the visible surface of the Sun. Convection cells of hot, bright gas rising up to the surface are surrounded by sinking, cool, darker material, giving the photosphere a granular appearance. These granules are grouped into supergranules, which can be more than 20 000 kilometres across.
"The peculiarity of what we are seeing is that the pore emerges at the edge of a supergranular cell Models have predicted that we would see this at the cell centre where the upflows are more significant," said Regnier.
The SDO observations allow Regnier to study temperature measurements ranging from 50000 to 10 million degrees Celsius on an almost second by second basis.
"In all temperature ranges, we can see the emerging area as a magnetic tube that is very hot at the edges and sharply delineated from the surrounding material. How sunspots are born, evolve and die is still a concern for solar physicists and one of the most intriguing subjects is to understand how these magnetic tubes can emerge from below the Sun's surface and push through into the hot atmosphere," said Regnier.
Fig. 1: SDO magnetic (top) and visible light (bottom) observations from SDO’s Helioseismic and Magnetic Imager (HMI) of an emerging active region on May 30 2010: (left) start of the emergence at 17:00 UT. On the magnetogram, the white is positive and the black is negative polarity; (middle) formation of a pore in the negative polarity at 22:00 UT. And (right) the active region on June 1 2010 at 18:00 UT.
Fig. 2: Composite image showing the temperature evolution of a slice through the emerging active region over time (increasing time from bottom to top). The bands show measurements taken at 5 thousand degrees, 0.6 million degrees, 1.6 million degrees, 2 million degrees and 10 million degrees Celsius.
The small image to the left if a snapshot of the emerging active region, the black line indicating the position of the slices;
Dr Stephane Regnier
Jeremiah Horrocks Institute
University of Central Lancashire
Tel: +44 (0)1772 89 2701
NAM 2011 Press Office (0900 – 1730 BST, 18-21 April only)
Venue Cymru conference centre
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Dr Robert Massey
Royal Astronomical Society
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Royal Astronomical Society
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NOTES FOR EDITORS
Bringing together around 500 astronomers and space scientists, the RAS National Astronomy Meeting 2011 (NAM 2011: http://www.ras.org.uk/nam-2011) will take place from 17-21 April in Venue Cymru (http://www.venuecymru.co.uk), Llandudno, Wales. The conference is held in conjunction with the UK Solar Physics (UKSP: http://www.uksolphys.org) and Magnetosphere Ionosphere and Solar-Terrestrial Physics (MIST: http://www.mist.ac.uk) meetings. NAM 2011 is principally sponsored by the RAS and the Science and Technology Facilities Council (STFC: http://www.stfc.ac.uk).
The Royal Astronomical Society
The Royal Astronomical Society (RAS: http://www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
The Science and Technology Facilities Council
The Science and Technology Facilities Council (STFC: http://www.stfc.ac.uk) ensures the UK retains its leading place on the world stage by delivering world-class science; accessing and hosting international facilities; developing innovative technologies; and increasing the socio-economic impact of its research through effective knowledge exchange. The Council has a broad science portfolio including Astronomy, Particle Astrophysics and Space Science. In the area of astronomy it funds the UK membership of international bodies such as the European Southern Observatory.
Venue Cymru (http://www.venuecymru.co.uk) is a purpose built conference centre and theatre with modern facilities for up to 2000 delegates. Located on the Llandudno promenade with stunning sea and mountain views; Venue Cymru comprises a stunning location, outstanding quality and exceptional value: the perfect conference package.