APOD: In Wolf's Cave (2011 Nov 19)

[APOD Robot]

In Wolf's Cave

Explanation: The mysterious blue reflection nebula found in catalogs as VdB 152 or Ced 201 really is very faint. It lies at the tip of the long dark nebula Barnard 175 in a dusty complex that has also been called Wolf's Cave. The cosmic apparitions are nearly 1,400 light-years away along the northern Milky Way in the royal constellation Cepheus. Near the edge of a large molecular cloud, pockets of interstellar dust in the region block light from background stars or scatter light from the embedded bright star giving the the nebula its characteristic blue color. Ultraviolet light from the star is also thought to cause a dim reddish luminescence in the nebular dust. Though stars do form in molecular clouds, this star seems to have only accidentally wandered into the area, as its measured velocity through space is very different from the cloud's velocity. This deep telescopic image of the region spans about 7 light-years.

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[orin stepanek]

This picture reminds me of another APOD where there was a nebula and a galaxy in the photo!

[neufer]

In Wolf's Cave

Explanation: The mysterious blue reflection nebula found in catalogs as VdB 152 or Ced 201 really is very faint. It lies at the tip of the long dark nebula Barnard 175 in a dusty complex that has also been called Wolf's Cave. The cosmic apparitions are nearly 1,400 light-years away along the northern Milky Way in the royal constellation Cepheus.

Walt Whitman on Shakespeare:
.

• <<Conceiv'd out of the fullest heat & pulse of European feudalism,
  personifying in unparallel'd ways the medieval aristocracy,
  its towering spirit of ruthless and gigantic caste, its own
  peculiar air and arrogance (no mere imitation) one of the
  wolfish earls so plenteous in the plays themselves, or some
  born descendent and knower, might seem to be the true author
  of those amazing works... I am firm against Shaksper.>>

[OverlordE]

Is this the way in or out? In any case it is interesting.

[Case]

This picture reminds me of another APOD where there was a nebula and a galaxy in the photo!

I presume you mean CG4 and PGC 21338. Yeah, there are some visual similarities.

[Ann]

It is definitely a very interesting image. One of the things that makes it so interesting is that you can actually tell that the blue star at the tip of the dark cloud was almost certainly not born out of this cloud. How can you tell?

Well, take a look at this image by Marcus Davies of a starforming region in Corona Australis. Another, smaller image of the same part of the sky, made by Loke Kun Tan, is here.


You can see that the starforming cloud in Corona Australis looks slightly similar to the Wold Cave's Nebula and its reflection nebula van den Bergh 152. The Corona Australis dust cloud is elongated, just like the Wolf's Cave, and there is one or more bright reflection nebulae at one end of it. But here the similarity ends.

The dust cloud in Corona Australis is obviously very much more turbulent than the Wolf's Cave dust cloud. The Corona Australis dust cloud looks distorted as if it had been torn and twisted by cosmic tornadoes. It is obvious, particularly in the largest version of Marcus Davies' image, that several stars are forming in the Corona Australis dark nebula. Apart from two prominent blue reflection nebulae, there are several other smaller reflection nebulae here too.

Compare the twisted structure and the many small reflection nebulae in the Corona Australis dust cloud with the single reflection nebula and "undisturbed appearance" of the Wolf Cave's nebula. Clearly the star that has made a blue reflection nebula here wasn't born here, but has just blundered into the dust cloud by chance. According to my software, the star lighting up the reflection nebula at the tip of the Wolf's Cave is SAO 10287, a ninth magnitude star of spectral class A. The bright blue stars born from the Corona Australis dust cloud are of late spectral class B, which isn't much different from SAO 10287. No, but the stars in Corona Australis are being boisterous and kicking up a storm, and don't we all know that babies should make all kinds of noise and commotion as they are being born? SAO 10287 is no baby, and it isn't disturbing its surroundings very much as it is passing quietly by.

Ann

[Kate]

Click to view full size image

Apologies for Saturday brain Wonderful photo!

[Wolf Kotenberg]

Where I hide, where I germinate my cosmic thoughts and questions

[starman]

That blue star is probably a 'runaway'. Close by is another runaway star (PV Cep) ploughing through a nebula. Runaway stars are typically associated with violent events such as supernovae. It's possible that there was a huge Supernova event not far from here (I'd say 'near' the star xi Cep - near in the sense of apparent position, not actual position; 'behind' xi Cep so to speak) since there are other areas of triggered star formation such as IC1396, the Cepheus OB1 and OB2 associations, and maybe a couple of others, at comparable distances.

[Celestine]

very interesting.... Thanks