X-Class solar flares?
484343
While I do not know the classification system thoroughly, I DO know that scientists are quite concerned about the effects of a high-powered solar flare knocking the earth's magnetic field all out of whack.  \n\nThe sun shoots off flares in cycles, and should reach a peak some time around 2011.  A giant flare could cause thousands of electic transformers world wide to blow.  These explosions wouldn't kill anybody, but would require that the transformers be replaced.  These things take months to build, and we couldn't replace them all for several years.
234992
There are several different types of eruptions from our Sun. The websites listed below with each type have photos and explanations ---\nSOLAR FLARES http://science.nasa.gov/ssl/pad/solar/flares.htm\n\nCORONAL MASS EJECTIONS\nhttp://science.nasa.gov/ssl/pad/solar/cmes.htm\n\nPROMINENCES\nhttp://science.nasa.gov/ssl/pad/solar/feature2.htm\n\nHELMET STREAMERS\nhttp://science.nasa.gov/ssl/pad/solar/feature3.htm\n\nPOLAR PLUMES\nhttp://science.nasa.gov/ssl/pad/solar/feature3.htm\n\nCORONAL LOOPS\nhttp://science.nasa.gov/ssl/pad/solar/feature3.htm\n\nGod is spelled B-I-G B-A-N-G\nPBrax@netscape.com
236138
http://albumen.stanford.edu/library/monographs/sunbeam/chap45.html\n___________\nthis one seems to have a lot of them, too\nhttp://scphillips.com/units/convfact.html
546706
Spectral classes refer to INDIVIDUAL stars. The Pleiades is a cluster of several stars, and M1 is the Crab Nebula.
75347
This question can't be adaquately addressed in this forum.  There are a couple websites you can refer to for these answers.\n\nhttp://solarsystem.nasa.gov\nhttp://www.nineplanets.org
632386
look here:\n\nhttp://neo.jpl.nasa.gov/cgi-bin/neo_ca\n\nselect what you want to see displayed from the pop-up menus and select display table.  try selecting "PHAs (Potentially Hazardous Asteroids)" from the first pop-up menu.
618441
The Sun is class G2V. A yellow dwarf.
313345
solar,  sun light, hydrogen
220029
According to the article, temperatures of several million degrees Kelvin — the temperature of solar flares.
940470
Possible, maybe. Likely, definitely not. The problem with flare stars (I assume you're talking about red dwarfs) is that any planet that orbits one has to orbit extremely close in order to receive enough heat to have liquid water on its surface (which is supposedly a precursor to life). At this range from the star, the planet will probably experience tidal lock, which would mean one side perpetually faces the star. The main problem is that at that close a range, any flare on the star could dramatically increase the brightness within minutes. Under unstable conditions like this, it is unlikely that advanced life would have the chance to evolve, because it is thought that advanced life needs to evolve under a relatively stable climate.
532257
A good approximation to the distribution of electromagnetic radiation emitted by the sun is given by the equation for a blackbody with a temperature of 5780 Kelvin:\n\nPower (Watts/meter^2 surface are/meter wavelength) = \n  2*pi*h*c^2/L^5*(exp(h*c/L*k*T)-1)\n\nwhere\n\nh = Planck's constant (6.626 x 10^-34 Joule*sec)\nc = speed of light (2.998 x 10^8 meters/sec)\nL = wavelength (meters)\nk = Boltzmann's constant (1.38 x 10^-23 Joule/Kelvin)\nT = temperature (Kelvin)\n\nThe sun's power output peaks in the visible portion (around a wavelength of 500nm) of the electromagnetic spectrum, but it emits over the entire range of possible wavelengths.\n\nIn reality, the solar spectrum is much more complicated than a simple blackbody curve because of the absorption of specific frequencies by the atoms making up the sun, as well as temperature inhomogeneities and effects due to the sun's magnetic field.
735634
Scientists using NASA's Spitzer Space Telescope have discovered and directly imaged a small brown dwarf star, 50 times the mass of Jupiter, orbiting with a planet around a Sun-like star. Such an arrangement has never before been seen but might be common, the scientists say, leading to solar systems with distorted planetary orbits.\n\nKevin Luhman of Penn State University is the lead author on a report describing this discovery, which will be published in The Astrophysical Journal. The discovery concerns a class of the coldest brown dwarfs, called T dwarfs.\n\n\nThe detailed research paper on T dwarf - Ref\nhttp://www.science.psu.edu/alert/Luhman9-2006-2.htm
890895
depends on charge density, configuration of layers, solar activity, magnetic field, etc\nf_{critical} = 9 x10^-3 /sqrt{N}, where N is electron density per cm^3\n\nIt's around 1-4MHz
687802
The brightest stars, the ones you can see with the naked eye, are all B8 and B9.  Some of the dimmer ones are of other classes--B,A,F, and perhaps some cooler classes, too.
1126540
I like this one,\nhttp://www.exploratorium.edu/ronh/solar_system/
632807
I will bring them all down for you baby.. haha\n\nbut seriously.. Sun is a star, and why would you choose a small rock circling around the Earth when you can pick a massive burning almost infinite fusion power plant that its presence is a key component of life.. I choose SUN !
695867
Solar flares are anomalis in the sun. They flare periodically. During the activity they produce intensed radiation. At this point if an astronauts is exposed and received this radiation he may absord a lethal dose of radiation.