Iris nebula
We are in the dead of winter, but it’s never too early to think spring. Here is a unique deep space object that’s astonishingly like the beautiful iris flowers that grow wild in our area in June. The Iris Nebula owes its novelty to the fact that it is primarily composed of copious amounts of very fine microscopic dust rather than hydrogen gas. A single intensely bright star (SAO 19158) 10 times the mass of our sun is the sole source of light in the dense cloud that literally blocks the light from a rich star field located behind it. Note the smokey brown/black dust cloud extending to the corners of the image.
The surface temperature of SAO 19158 makes it shine in blue light similar to the flame of a gas stove. The fine dust reflects and scatters the starlight much the same way as Earth’s atmosphere does to make our sky blue.
You can learn much about the star embedded in the Iris Nebula by observing how it carves out the surrounding dust cloud. Look closely at the cork screw shaped bright dust cloud swirling outward from the 11 o’clock position of the central star. That marks the location of one of the poles of SAO 19158. The star is slightly tilted so it’s upper pole is partially pointing at us making it the only one of the two that we can see. The spinning action of SAO 19158 shapes the nebula to make it look like an iris. Think of the “flower blossom” as a spinning 3D hourglass where the area around the star’s equator is pinched but spreads out above the poles.
Astronomer Gary Zientara owns Mount Sangre Observatory in Angel Fire, New Mexico.