doi:10.1038/nindia.2010.18 Published online 23 February 2010
What causes the Tsunami-like global waves that periodically ripple around the Sun? The answer lies in solar flares, tremendous explosions on the Sun's surface that drive high-frequency waves.
Large solar flares are suspected to stimulate oscillation of the entire Sun causing a thermal expansion. Earlier studies to relate the energy of these high frequency oscillations and flares using disk-integrated velocity observations of the Sun have remained unclear.
To get a clear picture, the researchers used data from the Michelson and Doppler Imager (MDI) and Global Oscillation at Low Frequency (GOLF) instrument on board Solar and Heliospheric Observatory (SOHO) spacecraft as also the Global Oscillation Network Group (GONG). They tracked the effects of flares in the time series of disk-integrated velocity signals from the solar surface.
The researchers noticed an increase in high-frequency global waves in the Sun during the flares. These observations open a new area of study on the excitation of global high-frequency waves by local tremors in the Sun launched during the solar flares.
"We are the first to show the influence of solar flares on the global velocity oscillations of the Sun using data from MDI and GOLF instruments on board SOHO," says Brajesh Kumar, one of the researchers.
The findings of the research could well be extended to study the influence of flares in other Sun-like stars, he adds.
The authors of this work are from: Udaipur Solar Observatory, Physical Research Laboratory, Udaipur; Indian Institute of Astrophysics, Bangalore, India and Laboratoire AIM, CEA/DSM-CNRS, Universit´e Paris, Diderot, IRFU/SAp, Centre de Saclay, Gif-sur-Yvette, France.
- Kumar, B. et al. On The Flare Induced High-Frequency Global Waves in the Sun. Astrophys. J. Lett. 711, L12-L18 (2010) | Article