Copyright: Naoyuki Kurita
I searched for a good RGB image of Zeta Ophiuchi to compare with today's infrared image APOD, and I found
the one on the left. The RGB image shows clearly that Zeta Ophiuchi is not in any way a red star, but it also doesn't look really bluish, but rather white. The non-red non-blue color of this star sitting in the middle of a large emission nebula shows that it is a hot star that is being reddened by dust.
More interesting is the RGB portrait of the large emission nebula surrounding Zeta Oph, Sharpless 2-27. Several "walls" of different kinds can be seen. The most obvious one is the bright (although somewhat "fluffy") red wall to the upper right of the star. The wall bifurcates at the left and the part nearest the star shows a bright knot, somewhat similar to
IC 63 near hot bright star Gamma Cassiopeia.
The second most obvious wall (or maybe the most obvious one) is a sharply defined, wiggling, slightly curving dark dust lane to the left of the star. This wall may possibly be affected by a moderately bright star immediately to the left of it. It is also possible that this dark dust lane is part of a background latticework of dust structures that has nothing to do with Zeta Ophiuchi.
There is a fascinating wall, extremely thin and straight, much closer than the sharply defined dust lane to the left of the Zeta Oph. If this line isn't a photographic artifact, I'm guessing that it marks one side of the boundary of a "cavity" that the hot star has blown around itself.
There is also a an ill-defined, comet tail-like red "wall" apparently emerging from the star itself and stretching downwards and to the right.
I have to wonder which, if any, of these visible walls and structures correspond to the dusty arc in today's APOD. Perhaps none of them do. The visible nebula, Sharpless 2-27, is huge in angular size, but I have no idea how close to or far away from the star the infrared dust arc is located.
Ann
[float=left][img2]http://www.ne.jp/asahi/stellar/scenes/object/zeta_oph.jpg[/img2][c][size=75]Copyright: Naoyuki Kurita[/size][/c][/float]I searched for a good RGB image of Zeta Ophiuchi to compare with today's infrared image APOD, and I found [url=http://www.ne.jp/asahi/stellar/scenes/object_e/zeta_oph.htm]the one on the left[/url]. The RGB image shows clearly that Zeta Ophiuchi is not in any way a red star, but it also doesn't look really bluish, but rather white. The non-red non-blue color of this star sitting in the middle of a large emission nebula shows that it is a hot star that is being reddened by dust.
More interesting is the RGB portrait of the large emission nebula surrounding Zeta Oph, Sharpless 2-27. Several "walls" of different kinds can be seen. The most obvious one is the bright (although somewhat "fluffy") red wall to the upper right of the star. The wall bifurcates at the left and the part nearest the star shows a bright knot, somewhat similar to [url=http://www.imagingdeepsky.com/Nebulae/IC59_IC63/IC59_IC63.htm]IC 63[/url] near hot bright star Gamma Cassiopeia.
The second most obvious wall (or maybe the most obvious one) is a sharply defined, wiggling, slightly curving dark dust lane to the left of the star. This wall may possibly be affected by a moderately bright star immediately to the left of it. It is also possible that this dark dust lane is part of a background latticework of dust structures that has nothing to do with Zeta Ophiuchi.
There is a fascinating wall, extremely thin and straight, much closer than the sharply defined dust lane to the left of the Zeta Oph. If this line isn't a photographic artifact, I'm guessing that it marks one side of the boundary of a "cavity" that the hot star has blown around itself.
There is also a an ill-defined, comet tail-like red "wall" apparently emerging from the star itself and stretching downwards and to the right.
I have to wonder which, if any, of these visible walls and structures correspond to the dusty arc in today's APOD. Perhaps none of them do. The visible nebula, Sharpless 2-27, is huge in angular size, but I have no idea how close to or far away from the star the infrared dust arc is located.
Ann