Explanation: This colorful skyscape features the dusty, reddish glow of Sharpless catalog emission region Sh2-155, the Cave Nebula. About 2,400 light-years away, the scene lies along the plane of our Milky Way Galaxy toward the royal northern constellation of Cepheus. Astronomical explorations of the region reveal that it has formed at the boundary of the massive Cepheus B molecular cloud and the hot, young, blue stars of the Cepheus OB 3 association. The bright rim of ionized hydrogen gas is energized by the radiation from the hot stars, dominated by the bright blue O-type star above picture center. Radiation driven ionization fronts are likely triggering collapsing cores and new star formation within. Appropriately sized for a stellar nursery, the cosmic cave is over 10 light-years across.
Whoops, Otto was still in government shutdown mode. How could I forget to flip that switch?
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 4:36 am
by Beyond
geckzilla wrote:Whoops, Otto was still in government shutdown mode. How could I forget to flip that switch?
No problemento, geckzilla. Now, if you would be so kind, could you flip the switch that explains why it is called the Cave Nebula I don't see any resemblance to a cave, what-so-ever.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 6:13 am
by Boomer12k
Beyond wrote:
geckzilla wrote:Whoops, Otto was still in government shutdown mode. How could I forget to flip that switch?
No problemento, geckzilla. Now, if you would be so kind, could you flip the switch that explains why it is called the Cave Nebula I don't see any resemblance to a cave, what-so-ever.
I guess it is that huge, dark, opening on the left????
But the right side of that area looks like a Bat Demon's Head......BAT CAVE NEBULA????
Nice picture.
:---[===] *
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 8:24 am
by Ann
That's a very nice image!
I checked the area with my software, and the blue stars are indeed very young. All are main sequence stars, and none is evolved, even though massive stars like these ones evolve very quickly.
All the brighter stars in the picture are far away. Even the red star is pretty far away, but it is a foreground object nonetheless. Its parallax is just a bit larger than the parallaxes of the blue stars, and its proper motion is quite different. I also think that the red star is a little bit less affected by dust than the blue stars, although I can't be sure. The blue stars are all quite reddened by all the dust around them. Most of them have apparent B-V indexes around +0.6, similar to the B-V index of the Sun, but in reality they have color indexes around -0.2.
According to my software there are at least two O stars among these stellar youngsters. Apart from the one at top, there is also the one at bottom right, whose lower diffraction spikes have been "cut off"!
Ann
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 12:14 pm
by starsurfer
Yay Jimmy Walker's finally got an APOD!
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 12:17 pm
by orin stepanek
I have to agree with Beyond: I don't see any semblance to a cave!
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 12:37 pm
by neufer
orin stepanek wrote:
Beyond wrote:
I don't see any resemblance to a cave, what-so-ever.
I have to agree with Beyond:
I don't see any semblance to a cave!
What a bunch of troglodytes!
Cave, n. [F. cave, L. cavus hollow, whence cavea cavity.]
1. A hollow place in the earth, either natural or artificial; a subterraneous cavity; a cavern; a den.
2. Any hollow place, or part; a cavity. [Obs.] "The cave of the ear." Bacon.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 12:50 pm
by bactame
Astronomer's are Platonist's so they have lots of ideas. Socrates had a whole Parable on a Cave. Unfortunately when you went in all the ideas you ran into were bright and shiny.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 12:57 pm
by Beyond
starsurfer wrote:Yay Jimmy Walker's finally got an APOD!
Yes, but he should change the color of the words that are in light-grey(?) on his home-page, so they are more easily readable.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 12:59 pm
by Beyond
neufer wrote:
orin stepanek wrote:
Beyond wrote:
I don't see any resemblance to a cave, what-so-ever.
I have to agree with Beyond:
I don't see any semblance to a cave!
What a bunch of troglodytes!
Cave, n. [F. cave, L. cavus hollow, whence cavea cavity.]
1. A hollow place in the earth, either natural or artificial; a subterraneous cavity; a cavern; a den.
2. Any hollow place, or part; a cavity. [Obs.] "The cave of the ear." Bacon.
I 'cave-in' at trying to grasp the meaning of this post.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 1:10 pm
by neufer
Click to play embedded YouTube video.
bactame wrote:
Astronomer's are Platonist's so they have lots of ideas.
Socrates had a whole Parable on a Cave.
Unfortunately when you went in all the ideas you ran into were bright and shiny.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 3:36 pm
by BMAONE23
orin stepanek wrote:I have to agree with Beyond: I don't see any semblance to a cave!
Rotate the image 90deg counterclockwise and the cave will appear
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 3:46 pm
by geckzilla
BMAONE23 wrote:
orin stepanek wrote:I have to agree with Beyond: I don't see any semblance to a cave!
Rotate the image 90deg counterclockwise and the cave will appear
mcdonaldsarchnebula2.jpg (70.49 KiB) Viewed 3951 times
mcdonaldsarchnebula1.jpg (71.79 KiB) Viewed 3951 times
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 4:00 pm
by Beyond
Nope Still no cave. Perhaps if there was a photo from an old antique telescope with a lot less definition
And...
I'll have an extra large fries and strawberry shake with the Big Mac.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 5:24 pm
by Psnarf
Suitable APOD for the Halloween Season: the Cave Nebula Wizard.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 6:10 pm
by geckzilla
I see Death's scythe in that cropped view, Psnarf.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 6:59 pm
by Beyond
Sigh, i don't.
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 7:01 pm
by rstevenson
I seem to be in Beyonder Land on this too. I'm rarely able to see what others see in these sorts of images. We must be less suggestible than most, B.
Rob
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 7:09 pm
by Beyond
rstevenson wrote:I seem to be in Beyonder Land on this too. I'm rarely able to see what others see in these sorts of images. We must be less suggestible than most, B.
Rob
Rob, maybe we're just the "sanest" and don't know it?
Re: APOD: Sh2 155: The Cave Nebula (2013 Oct 19)
Posted: Sat Oct 19, 2013 7:29 pm
by orin stepanek
Beyond wrote:
rstevenson wrote:I seem to be in Beyonder Land on this too. I'm rarely able to see what others see in these sorts of images. We must be less suggestible than most, B.
Rob
Rob, maybe we're just the "sanest" and don't know it?