Find the set of conditions that best matches the Eagle Nebula.But the intensity of OIII and SII emission does not seem to depend much on metallicity what other mechanism is at work to reduce emissivity with increased metallicity? This increases the abundance of oxygen and sulphur, which you might expect to increase the emissivity of OIII and SII. To view the full image collection and see download options, including compass images with scale. The seething star forming this nebula is 45 times more massive than our sun. Increase the ionization parameter and see the ionization front advance (and the SII emission peak with it). Zoomable Image: Southern Ring Nebula 4,833 x 4,501 px. The Bubble Nebula is seven light-years acrossabout one-and-a-half times the distance from our sun to its nearest stellar neighbor, Alpha Centauri, and resides 7,100 light-years from Earth in the constellation Cassiopeia.Increase the temperature of the nebula’s star to see the OIII emission increase.Look at the density gradient and compare it to the Hα emission.You can try out a simple model by using the interactive nebula predictor. To find the properties of the gas in nebulae, astronomers make models to predict what light emission to expect under different conditions. The neutral hydrogen density rises rapidly at the photoionization front, and so does the singly ionized sulphur abundance. Sulphur is very easy to ionize twice, so singly ionized sulphur is found when doubly ionized sulphur gains an electron from a hydrogen atom: S ++ + H 0 → S + + H +. High energy radiation is needed to ionize oxygen twice, and hotter stars emit more high energy radiation.įinally, SII emission (in red) traces the ionization front. OIII emission (in blue) indicates the temperature of the star.
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