The researchers used infrared data from the Hubble Space Telescope's Wide-Field Camera 3 (WFC3) and from the Keck OSIRIS spectrograph to characterize BX442's structure. They identified two distinct arms and a probable third arm using emission from stars and ionized hydrogen gas. Spiral arms in modern galaxies trace the presence of star formation and the hottest, youngest stars, which also seems to be the case with BX442. In fact, based on analysis with the Keck ultraviolet Low Resolution Imaging Spectrometer (LRIS), BX442 is hotter than comparable modern galaxies. The temperature is measured by the velocity of gas inside the galaxy, relative to the rotation rate of the galactic disk.Because of the transient nature of gravitational disturbances, the researchers pointed out that BX442's spiral arms may have been a temporary feature. If that was the case, it would also help explain why no other galaxies in the sample of 306 possessed spiral arms: they hadn't experienced a clo!
se passage within the time frame of the observation. However, it isn't possible to rule out selection effects entirely: BX442 is nearly face-on to Earth and very clear, but at the huge distances, not every galaxy is as beautifully defined.<br />http://arstechnica.com/science/2012/07/a-hot-young-spiral-galaxy-is-the-farthest-yet-seen/
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