Starship Asterisk*

APOD Robot wrote: ↑Thu Sep 06, 2018 4:06 am Along the Western Veil

Explanation: Delicate in appearance, these filaments of shocked, glowing gas, are draped across planet Earth's sky toward the constellation of Cygnus. They form the western part of the Veil Nebula. The Veil Nebula itself is a large supernova remnant, an expanding cloud born of the death explosion of a massive star. Blasted out in the cataclysmic event, the interstellar shock wave plows through space sweeping up and exciting interstellar material. The glowing filaments are really more like long ripples in a sheet seen almost edge on, remarkably well separated into atomic hydrogen (red) and oxygen (blue-green) gas.

Devil Particle wrote: ↑Thu Sep 06, 2018 1:09 pm There seems to be a lot of hydrogen and oxygen in this nebula. Is there anything that stops these elements from combining to form water?

Ann wrote: ↑Thu Sep 06, 2018 10:54 am Planetary nebulas and supernova remnants don't interest me that much. But there is one thing about the Cygnus Loop that is interesting to me, and that is the dichotomy of its color. The red light comes from hydrogen emission, and the blue-green light comes from oxygen emission. The blue-green emission represents a higher level of ionization than the red emission, and that is because the blue light show us where the expanding nebula is crashing into the interstellar medium. The red parts of the nebula just follow along after the blue-green parts have mostly cleared the way for them, like a snowplow.

Now that is cool!

Ann

MarkBour wrote: ↑Thu Sep 06, 2018 4:44 pm

Ann wrote: ↑Thu Sep 06, 2018 10:54 am Planetary nebulas and supernova remnants don't interest me that much. But there is one thing about the Cygnus Loop that is interesting to me, and that is the dichotomy of its color. The red light comes from hydrogen emission, and the blue-green light comes from oxygen emission. The blue-green emission represents a higher level of ionization than the red emission, and that is because the blue light show us where the expanding nebula is crashing into the interstellar medium. The red parts of the nebula just follow along after the blue-green parts have mostly cleared the way for them, like a snowplow.

Now that is cool!

Ann

Yes, that is cool!

For the material ejected from a dying star, it seems that the various elements are not thoroughly mixed together. Rather, it always seems to be the case that elements like Si, S, O are ejected most abundantly in certain patches, or bands, of the planetary nebula.

... Light from the original supernova explosion likely reached Earth over 5,000 years ago.
...While that translates to over 70 light-years (wide) at its estimated distance of 1,500 light-years,

grump wrote: ↑Thu Sep 06, 2018 9:58 pm

... Light from the original supernova explosion likely reached Earth over 5,000 years ago.
...While that translates to over 70 light-years (wide) at its estimated distance of 1,500 light-years,

If light from the original supernova arrived 5000 years ago, wouldn't it be 5000 light years distant? Please explain?

BDanielMayfield wrote: ↑Thu Sep 06, 2018 4:57 pm ...
Interesting idea Mark. Perhaps this separation of elements in SN remnants can be traced back to the "onion-like" layering of heavier elements inside a SN progenitor.

Bruce

>>>https://sites.ualberta.ca/~pogosyan/tea ... ure18.html<<<

grump wrote: ↑Thu Sep 06, 2018 9:58 pmIf light from the original supernova arrived 5000 years ago, wouldn't it be 5000 light years distant? Please explain?

rstevenson wrote: ↑Fri Sep 07, 2018 1:06 am ... the light from the supernova came from an event that took place about 1500 ly from Earth, and that light arrived here at least 5000 years ago. So the supernova itself took place about 6500 years ago.

grump wrote: ↑Sun Sep 09, 2018 10:39 pm

rstevenson wrote: ↑Fri Sep 07, 2018 1:06 am
... the light from the supernova came from an event that took place about 1500 ly from Earth, and that light arrived here at least 5000 years ago. So the supernova itself took place about 6500 years ago.

Ah - the penny drops. Thank you.

neufer wrote: ↑Mon Sep 10, 2018 12:02 pm
Twenty years ago when Dr. Ellie Arroway received a 1988 radio signal containing a series of prime numbers coming from the direction of Vega system... that was curious. Further analysis revealeds information in the polarization modulation of the signal. The message was a retransmission of Adolf Hitler's opening speech at the 1936 Summer Olympics in Berlin; the first television signal powerful enough to escape Earth's ionosphere. This round trip delay of 52 years clarified that the signal was, indeed, coming from 26 light years away.

Ann wrote: ↑Mon Sep 10, 2018 1:17 pm

neufer wrote: ↑Mon Sep 10, 2018 12:02 pm
Twenty years ago when Dr. Ellie Arroway received a 1988 radio signal containing a series of prime numbers coming from the direction of Vega system... that was curious. Further analysis revealeds information in the polarization modulation of the signal. The message was a retransmission of Adolf Hitler's opening speech at the 1936 Summer Olympics in Berlin; the first television signal powerful enough to escape Earth's ionosphere. This round trip delay of 52 years clarified that the signal was, indeed, coming from 26 light years away.

• That's amazing.

https://en.wikipedia.org/wiki/Crop_circle wrote:

A crop circle with the logo of Swedish Railways.

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<<The number of crop circles has substantially increased from the 1970s to current times. There has been little scientific study of them. Circles in the United Kingdom are not distributed randomly across the landscape but appear near roads, areas of medium to dense population and cultural heritage monuments, such as Stonehenge or Avebury. Formations are usually created overnight, although some are reported to have appeared during the day.>>