The Chandra X-Ray telescope observed an outburst of x-rays from the star in McNeil's nebula. This nebula in the constellation of Orion is illuminated by a very young star that undergoes periods of brightening. This star is a bright infrared and optical source at the apex of the nebula. It appears along with three other stars as a point source in the x-ray image. The star was observed to brighten in x-ray by a factor of 50 from an observation of March 7, 2004 to an observation of March 22, 2004, which bracketed the beginning of the optical flare. The results appear in an article by J. Kastner et al. in the July 22, 2004 issue of Nature.
The current theory is that a disk of material orbiting the star is accreting onto the star, and that occasionally, because of the generation and expulsion of magnetic fields within the disk, the accretion rate dramatically increases. The higher accretion rate leads to a brightening at optical wavelengths, while the expulsion of the magnetic field leads to a brightening in the x-ray. Amateur astronomer Jeff McNeil discovered the eponomous nebula with a 3-inch telescope in January of 2004.
The nebula is located at Right Ascension 05:46:13.10s and declination -00:06:05.00. The nebula is estimated to be at 400pc.