That is a very nice picture!
And the Fox Fur and Christmas Tree pariedolia objects in the pareidolia constellation of the Unicorn are standouts in one of my favorite regions of the sky. Particularly because so much of this cosmic eye candy owes its presence to one of the bluest stars in the sky, S (or 15) Monocerotis.
S Monocerotis is so blue because it is intrinsically very hot, at spectral class O7V, but also because the star is relatively unreddened from our point of view, unlike most O-type stars in the sky.
When I checked the Hipparcos parallax of S Monocerotis, I thought that the star was disappointingly faint. Part of the reason for its relative faintness is undoubtedly the sheer youth of the star, because stars get brighter as they age. But it wouldn't surprise me if S Mon really is kind of faint for its spectral class, because I have come to believe that the spectral class and the luminosity of stars aren't always that strongly tied together.
The youth of S Monocerotis can be inferred from the fact that the star hasn't had time to blow away all the dust in its vicinity, even though it has cleared a cavity for itself. The Fox Fur Nebula owes its tattered appearance to the strong winds of S Mon, and the Fox Fur is doomed. Note that you can see blue background light peek through tears in the Fox Fur. There is also a dusty blue reflection nebula to the right of the Fox Fur in this APOD. There are no such things to be seen in nebulas surrounding older O-type stars.
Note, too, that there is a structure far to the left in the picture that is somewhat similar to the well-known Cone Nebula far to the right in this picture. Both are windblown "pillars" sculpted by the winds of S Mon.
Obviously I like today's APOD because it is an RGB image that brings out the lovely blue, pink och yellow color of this spectacular skyscape!
Ann
That is a very nice picture! :D And the Fox Fur and Christmas Tree pariedolia objects in the pareidolia constellation of the Unicorn are standouts in one of my favorite regions of the sky. Particularly because so much of this cosmic eye candy owes its presence to one of the bluest stars in the sky, S (or 15) Monocerotis.
S Monocerotis is so blue because it is intrinsically very hot, at spectral class O7V, but also because the star is relatively unreddened from our point of view, unlike most O-type stars in the sky.
When I checked the Hipparcos parallax of S Monocerotis, I thought that the star was disappointingly faint. Part of the reason for its relative faintness is undoubtedly the sheer youth of the star, because stars get brighter as they age. But it wouldn't surprise me if S Mon really is kind of faint for its spectral class, because I have come to believe that the spectral class and the luminosity of stars aren't always that strongly tied together.
The youth of S Monocerotis can be inferred from the fact that the star hasn't had time to blow away all the dust in its vicinity, even though it has cleared a cavity for itself. The Fox Fur Nebula owes its tattered appearance to the strong winds of S Mon, and the Fox Fur is doomed. Note that you can see blue background light peek through tears in the Fox Fur. There is also a dusty blue reflection nebula to the right of the Fox Fur in this APOD. There are no such things to be seen in nebulas surrounding older O-type stars.
Note, too, that there is a structure far to the left in the picture that is somewhat similar to the well-known Cone Nebula far to the right in this picture. Both are windblown "pillars" sculpted by the winds of S Mon.
Obviously I like today's APOD because it is an RGB image that brings out the lovely blue, pink och yellow color of this spectacular skyscape! :D
Ann