APOD: Along the Western Veil (2018 Sep 06)

[APOD Robot]

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. Light from the original supernova explosion likely reached Earth over 5,000 years ago. 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. Also known as the Cygnus Loop, the Veil Nebula now spans nearly 3 degrees or about 6 times the diameter of the full Moon. While that translates to over 70 light-years at its estimated distance of 1,500 light-years, this telescopic two panel mosaic image of the western portion spans about half that distance. Brighter parts of the western Veil are recognized as separate nebulae, including The Witch's Broom (NGC 6960) along the top of this view and Pickering's Triangle (NGC 6979) below and left.

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[Boomer12k]

A "Sharp tailed SPACE SCORPION"!!!! Yeah...cooool....

:---[===]*

[starsurfer]

Somewhere in this image is a planetary nebula!

[Ann]

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 shows 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

[neufer]

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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]

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?

[Chris Peterson]

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?

Making water out of hydrogen and oxygen isn't as simple as just mixing the two together. Water certainly forms in space, but it's typically on the surface of dust where other elements can act as catalysts and intermediate products like peroxide can form.

[Sa Ji Tario]

The image reminds me of the head of an Afghan hound

[saturno2]

Strange image

[Joe Stieber]

Bob King just posted a nice article, Explore the Veil Nebula, at Sky & Telescope online.

[MarkBour]

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.

[BDanielMayfield]

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.

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

[grump]

... 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?

[Chris Peterson]

... 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?

Light emitted by the Sun arrived at the Earth 5000 years ago, which doesn't mean the Sun is 5000 light years distant.

Although we don't usually concern ourselves with "when" something actually occurred, only when it was first observable, consider in this case that the object was 1500 ly distant, and the light reached the Earth 5000 years ago. You could interpret that as telling us that the event occurred 5000 + 1500 = 1600 6500 years ago.

[MarkBour]

...
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

Thanks for mentioning that, Bruce. I looked it up and here is a reference to what you're saying:

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

It makes sense that if they're pretty segregated in the star, they'll not be all mixed-up when they're released, and maybe they even remain in distinct shells at first. I suppose there may be differences in the kinetic energy imparted to the different atoms/molecules.

[rstevenson]

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

There was lots of light arriving at the Earth 5000 years ago, some (as Chis mentioned) from our Sun, which is only about 8 light-minutes away, some from Saturn (about 1.3 light-hours away on average), some from distant galaxies which could be millions of light years away, and so on. And all of it would arrive at more or less the same time, but took very different amounts of time to get here.

The description says that 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.

Rob

[grump]

... 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]

... 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.

Placing a coin in a slot and then hearing it fall is a 2-stage process.

Radar & lidar are also 2-stage processes of sending out signal pulses and then listening for the echos.

When a lidar pulse to Apollo retro reflectors takes two and a half seconds for its round trip we know that the Moon is one and a quarter light seconds away.

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]

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.

Ann

[neufer]

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.

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.>>