Starship Asterisk*

by **TheZuke!** » Fri Jun 19, 2020 1:43 pm

Grizzly wrote: ↑Fri Jun 19, 2020 3:28 am And while on the subject of pareidolia, does anyone see the head / face in the cloud top left of the picture? It is gazing slightly to the right.

Do you mean this one?

or this one?

by **Grizzly** » Fri Jun 19, 2020 3:28 am

And while on the subject of pareidolia, does anyone see the head / face in the cloud top left of the picture? It is gazing slightly to the right.

by **Chris Peterson** » Thu Jun 18, 2020 5:48 pm

Ann wrote: ↑Thu Jun 18, 2020 3:46 pm I hope the moderators will forgive me, because I'm going to do something that I have never done before - post a picture that is clearly too big, 1.4 MB.

That is not considered a large image anymore. And to be sure, the site has been set up to cap the maximum size of uploads. Basically, if the uploader accepts your file, the size is acceptable. You should not have to concern yourself with the matter.

by **bystander** » Thu Jun 18, 2020 5:24 pm

Ann wrote: ↑Thu Jun 18, 2020 3:46 pm I hope the moderators will forgive me, because I'm going to do something that I have never done before - post a picture that is clearly too big, 1.4 MB.

Don't hot link them, try uploading as an attachment.
See How to post images: Method 2

by **Ann** » Thu Jun 18, 2020 3:54 pm

ems57fcva wrote: ↑Thu Jun 18, 2020 3:33 pm
Ann wrote: ↑Thu Jun 18, 2020 5:59 am
ems57fcva wrote: ↑Thu Jun 18, 2020 4:27 am Interesting picture, but what intrigues me are the bends in the "tadpole" tails. Both have the same set of shifts. It appears that the interstellar wind in that area was "blowing" in one direction, then shifted to another direction, and then shifted back. Speculation: A nearby supernova affected the area around the tadpoles, creating an area of altered wind flow. That area was eventually pushed away by the main stellar wind, at which time the original flow was restored.
...

The force that hit the pillars must have been sufficiently strong to bend them, but not strong enough to break them apart or evaporate them. It must have been a very temporary event, too. I can't believe that the direct impact of a supernova would not have destroyed the pillars, but maybe, if the supernova was partially shielded from the pillars, they would just feel a dampened shock wave from it?

Or maybe it wasn't a supernova at all, but a less energetic temporary event that still generated a shock wave strong enough to bend the pillars?

Is that possible?

Ann
One possibility that I thought of was a T Tauri wind, but those pillars are 10 light years long according to the APOD. A strong solar wind would not be enough to create light-years-long bends in those tails. At the same time I am also thinking that an outright shock wave is not the answer: That would have severed the tails instead of merely bending them. This is a change of direction in the local interstellar wind, not a total change of environment, but it also is a change the occurred in an area several light-years across.

I return to the idea of local supernova, but none too close. The Vela-type shock wave never got to the tadpoles. Instead the gas which was pushed out of the way created a pressure wave and that is what "hit" the Tadpoles. Then you have what is affecting the Tadpoles being the stellar winds from the nearly stars the whole time, but that wind has itself been buffeted by the supernova.

FWIW: IC410 does seem to be on one side of a cavity with the Flaming Star Nebula being on the other. If that cavity was created by a supernova it would fit the bill of an event whose shock wave did not reach the Tadpoles but did affect them.

I really think you are right that some sort of force made the tadpoles bend, but I don't have the mathematical understanding to meaningfully discuss what this force might have been. Your explanation seems plausible to me, with one exception. There is no cavity between IC 410 and IC 405, because IC 410 is located some six times farther away from us than IC 405.

Ann

by **Ann** » Thu Jun 18, 2020 3:46 pm

I hope the moderators will forgive me, because I'm going to do something that I have never done before - post a picture that is clearly too big, 1.4 MB.

IC 410 (at left, with tadpoles), and IC 405 (at right, with star AE Aurigae
and The Flaming Star Nebula). Photo: Éder Ívan.
https://www.astroeder.com/rimg/92/0/390 ... _ederL.jpg

: IC 410 (left) and IC 405 (right). Note the different shades of red in IC 410 and IC 405. The difference is due to more dust reddening in IC 410 due to its greater distance from us. Photo: christensenastroimages.com.

IC 410 (with the tadpoles) and IC 405 (with AE Aurigae and the Flaming Star Nebula) seem to be located right next to one another in the sky. However, they are at wildly different distances. IC 410 is about 10,000 light-years away, whereas IC 405 is only about 1,500 light-years away.

Note how different they are. IC 10 is illuminated by a brilliant young star cluster, while IC 405 is lit up by a single runaway hot star, AE Aurigae, that is plunging its way through a cloud of gas and dust that just happened to be in its way. The red parts of IC 405 is hydrogen being ionized by the ultraviolet light from AE Aurigae, while the blue parts are dust that reflects the optical blue light from the hot star.

IC 410 is much farther away than IC 410, and it is considerably more reddened, which is particularly obvious in the picture at right. IC 410 contains a powerful young cluster, NGC 1893, whose combined ultraviolet emission and stellar winds are much more powerful than anything that AE Aurigae can produce on its own. The cluster has blown a cavity in the cloud of gas and dust that it was born from, slightly similar to the Rosette Nebula, seen here in a picture by Greg Polanski.

: Two tadpoles? Or two bats?

Note that you can easily see the tadpoles in IC 410 in the picture at top left by Éder Ívan. The tadpoles seem to be "hanging down" from the "ceiling" of IC 410 like a pair of bats.

Ann

by **ems57fcva** » Thu Jun 18, 2020 3:33 pm

Ann wrote: ↑Thu Jun 18, 2020 5:59 am
ems57fcva wrote: ↑Thu Jun 18, 2020 4:27 am Interesting picture, but what intrigues me are the bends in the "tadpole" tails. Both have the same set of shifts. It appears that the interstellar wind in that area was "blowing" in one direction, then shifted to another direction, and then shifted back. Speculation: A nearby supernova affected the area around the tadpoles, creating an area of altered wind flow. That area was eventually pushed away by the main stellar wind, at which time the original flow was restored.
...

The force that hit the pillars must have been sufficiently strong to bend them, but not strong enough to break them apart or evaporate them. It must have been a very temporary event, too. I can't believe that the direct impact of a supernova would not have destroyed the pillars, but maybe, if the supernova was partially shielded from the pillars, they would just feel a dampened shock wave from it?

Or maybe it wasn't a supernova at all, but a less energetic temporary event that still generated a shock wave strong enough to bend the pillars?

Is that possible?

Ann

One possibility that I thought of was a T Tauri wind, but those pillars are 10 light years long according to the APOD. A strong solar wind would not be enough to create light-years-long bends in those tails. At the same time I am also thinking that an outright shock wave is not the answer: That would have severed the tails instead of merely bending them. This is a change of direction in the local interstellar wind, not a total change of environment, but it also is a change the occurred in an area several light-years across.

I return to the idea of local supernova, but none too close. The Vela-type shock wave never got to the tadpoles. Instead the gas which was pushed out of the way created a pressure wave and that is what "hit" the Tadpoles. Then you have what is affecting the Tadpoles being the stellar winds from the nearly stars the whole time, but that wind has itself been buffeted by the supernova.

FWIW: IC410 does seem to be on one side of a cavity with the Flaming Star Nebula being on the other. If that cavity was created by a supernova it would fit the bill of an event whose shock wave did not reach the Tadpoles but did affect them.

by **orin stepanek** » Thu Jun 18, 2020 12:26 pm

Tadpoles is really a good name for these guys!

by **Ann** » Thu Jun 18, 2020 5:59 am

ems57fcva wrote: ↑Thu Jun 18, 2020 4:27 am Interesting picture, but what intrigues me are the bends in the "tadpole" tails. Both have the same set of shifts. It appears that the interstellar wind in that area was "blowing" in one direction, then shifted to another direction, and then shifted back. Speculation: A nearby supernova affected the area around the tadpoles, creating an area of altered wind flow. That area was eventually pushed away by the main stellar wind, at which time the original flow was restored.

Indeed, the identical bends in the tadpole tails are interesting.

: The Vela Supernova remnant. There are lots of shock waves here. Photo: Harel Boren.

I'm thinking that a jet of some kind hit hit these dust pillars. Or, come to think of it, more likely a shock wave than a jet.

I'm guessing that the two Tadpole pillars are light-years apart, which suggests that whatever force they were subjected to hit one of the pillars before it hit the other one.

The force that hit the pillars must have been sufficiently strong to bend them, but not strong enough to break them apart or evaporate them. It must have been a very temporary event, too. I can't believe that the direct impact of a supernova would not have destroyed the pillars, but maybe, if the supernova was partially shielded from the pillars, they would just feel a dampened shock wave from it?

Or maybe it wasn't a supernova at all, but a less energetic temporary event that still generated a shock wave strong enough to bend the pillars?

Is that possible?

Ann

by **ems57fcva** » Thu Jun 18, 2020 4:27 am

Interesting picture, but what intrigues me are the bends in the "tadpole" tails. Both have the same set of shifts. It appears that the interstellar wind in that area was "blowing" in one direction, then shifted to another direction, and then shifted back. Speculation: A nearby supernova affected the area around the tadpoles, creating an area of altered wind flow. That area was eventually pushed away by the main stellar wind, at which time the original flow was restored.

by **APOD Robot** » Thu Jun 18, 2020 4:06 am

The Tadpoles of IC 410

Explanation: This telescopic close-up shows off the central regions of otherwise faint emission nebula IC 410, captured under backyard suburban skies with narrowband filters. It also features two remarkable inhabitants of the cosmic pond of gas and dust. Below and right of center are the tadpoles of IC 410. Partly obscured by foreground dust, the nebula itself surrounds NGC 1893, a young galactic cluster of stars. Formed in the interstellar cloud a mere 4 million years ago, the intensely hot, bright cluster stars energize the glowing gas. Composed of denser cooler gas and dust, the tadpoles are around 10 light-years long and are likely sites of ongoing star formation. Sculpted by stellar winds and radiation their heads are outlined by bright ridges of ionized gas while their tails trail away from the cluster's central young stars. IC 410 lies some 10,000 light-years away, toward the nebula-rich constellation Auriga.

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