View Full Version : Killer Solar Flare... on Another Star

2006-Nov-08, 01:56 AM
NASA's Swift satellite has spotted one of the most powerful stellar flares ever seen. Fortunately, this killer blast happened on a star located about 135 light-years from Earth. Had the flare occurred on the Sun, it would have triggered a mass extinction on our planet. The flaring star, II Pegasi, has a stellar companion in a very tight orbit. Their interaction has caused the tidally locked stars to spin very quickly. It's this rapid rotation that leads to powerful stellar flares.

Read the full blog entry (http://www.universetoday.com/2006/11/07/killer-solar-flare-on-another-star/)

2006-Nov-08, 02:22 PM
The energy of these events is sobering...I think it does lend credence to the hypothesis that comets act as a trigger of some local flaring...good graduate project for someone out there with a good head for statistics.

2006-Nov-08, 02:33 PM
I think it does lend credence to the hypothesis that comets act as a trigger of some local flaring...
The comet we saw in the SOHO images a few days ago lends some credence to the idea that a limited number of CMEs might be from comets, but the event described in this article is clearly not a comet.

2006-Nov-09, 04:58 PM
I didn't hunt it down, but is this not the magnetar sgr1806-20?

2006-Nov-09, 05:58 PM
II Pegasi (HD 224085) is a 7.6 V-magnitude spectroscopic binary at
Position(2000): R.A. = 23 55 04.05 Dec.= +28 38 01.2

SGR 1806-20 is at
Position(2000): R.A. = 18h08.5m, Dec.= -20d23.0m

Title: Nonthermal Hard X-ray Emission and Iron Kalpha Emission from a Superflare on II Pegasi
Authors: R. A. Osten, S. Drake, J. Tueller, J. Cummings, M. Perri, A. Moretti and S. Covino

Abstract. We report on an X-ray flare detected on the active binary system II~Pegasi with the Swift telescope. The trigger had a 10-200 keV luminosity of 2.2 imes10^32 erg s^-1-- a superflare, by comparison with energies of typical stellar flares on active binary systems. The trigger spectrum indicates a hot thermal plasma with T~ 180 x 10^6 K. X-ray spectral analysis from 0.8--200 keV with the X-Ray Telescope and BAT in the next two orbits reveals evidence for a thermal component (T>80 x 10^6 K) and Fe K 6.4 keV emission. A tail of emission out to 200 keV can be fit with either an extremely high temperature thermal plasma (T ~ 3 x 10^8 K) or power-law emission. Based on analogies with solar flares, we attribute the excess continuum emission to nonthermal thick-target bremsstrahlung emission from a population of accelerated electrons. We estimate the radiated energy from 0.01--200 keV to be ~6 x 10^36 erg, the total radiated energy over all wavelengths sim10^38 erg, the energy in nonthermal electrons above 20 keV ~ 3 x 10^40 erg, and conducted energy <5 x 10^43 erg. The nonthermal interpretation gives a reasonable value for the total energy in electrons > 20 keV when compared to the upper and lower bounds on the thermal energy content of the flare. This marks the first occasion in which evidence exists for nonthermal hard X-ray emission from a stellar flare. We investigate the emission mechanism responsible for producing the 6.4 keV feature, and find that collisional ionisation from nonthermal electrons appears to be more plausible than the photoionisation mechanism usually invoked on the Sun and pre-main sequence stars.

Read more (http://arxiv.org/PS_cache/astro-ph/pdf/0609/0609205.pdf) (1.79mb, PDF)

2006-Nov-09, 07:21 PM
Thanks Blob. It is an interesting coincidence they both surprisingly bright stars were in December. [Hmmmm, are these coordinates in the east? ;) ]

2006-Nov-10, 01:54 AM
Non thermal emmisions. Mmmmm......very interesting!!!

2006-Dec-22, 06:02 PM