APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

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APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by APOD Robot » Sun Apr 08, 2018 4:10 am

Image NGC 6960: The Witch's Broom Nebula

Explanation: Ten thousand years ago, before the dawn of recorded human history, a new light would have suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was from a supernova, or exploding star, and record the expanding debris cloud as the Veil Nebula, a supernova remnant. This sharp telescopic view is centered on a western segment of the Veil Nebula cataloged as NGC 6960 but less formally known as the Witch's Broom Nebula. Blasted out in the cataclysmic explosion, the interstellar shock wave plows through space sweeping up and exciting interstellar material. Imaged with narrow band filters, the glowing filaments are like long ripples in a sheet seen almost edge on, remarkably well separated into atomic hydrogen (red) and oxygen (blue-green) gas. The complete supernova remnant lies about 1400 light-years away towards the constellation Cygnus. This Witch's Broom actually spans about 35 light-years. The bright star in the frame is 52 Cygni, visible with the unaided eye from a dark location but unrelated to the ancient supernova remnant.

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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by MarkBour » Sun Apr 08, 2018 8:26 am

What a beautifully colored, crisp image!

I wonder, when a supernova makes clouds with hydrogen and oxygen, do they form many water molecules on their journey?
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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by neufer » Sun Apr 08, 2018 12:32 pm

MarkBour wrote:
Sun Apr 08, 2018 8:26 am

I wonder, when a supernova makes clouds with hydrogen and oxygen, do they form many water molecules on their journey?
https://physicsworld.com/a/alma-reveals-new-molecules-in-famous-supernova/ wrote: .
ALMA reveals new molecules in famous supernova
Sarah Tesh, Stars and solar physics Research update: 11 Jul 2017


<<Two previously unseen molecules have been detected within the remnant of supernova 1987A. Using the Atacama Large Millimeter/submillimeter Array (ALMA), Mikako Matsuura from Cardiff University in the UK and colleagues have found formylium (HCO+) and sulphur monoxide (SO) alongside previously detected compounds such as carbon monoxide (CO) and silicon oxide (SiO).

Supernova 1987A (SN 1987A) is located 163,000 light-years away and its dramatic explosion was witnessed, as the name suggests, in 1987. Observations over the following 30 years have revealed details about how stars die and how their atoms – such as carbon, oxygen and nitrogen – spread into space. In the past, scientists believed the molecules and dust present within a star would be destroyed during a supernova explosion. However, observations of molecules in SN 1987A suggest otherwise, and the current study, presented in Monthly Notices of the Royal Astronomical Society, further supports an alternative fate.

Our results have shown that as the leftover gas from a supernova begins to cool down to below –200 °C, the many heavy elements that are synthesised can begin to harbour rich molecules, creating a dust factory,” explains Matsuura. “What is most surprising is that this factory of rich molecules is usually found in conditions where stars are born. The deaths of massive stars may therefore lead to the birth of a new generation.

The international team has also published an accompanying study in The Astrophysical Journal Letters. In this work they used ALMA data to build detailed 3D maps of CO and SiO inside SN 1987A. These show vast stores of the molecules in discrete clumps within remnant core. The new data will help astronomers test and improve their simulations of supernova evolution.>>
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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by Chris Peterson » Sun Apr 08, 2018 1:57 pm

MarkBour wrote:
Sun Apr 08, 2018 8:26 am
What a beautifully colored, crisp image!

I wonder, when a supernova makes clouds with hydrogen and oxygen, do they form many water molecules on their journey?
There is certainly water in the interstellar medium, a product of reactions around supernovas and other phenomena that release hydrogen and oxygen. But water is more concentrated in molecular clouds, where we have material coming together, not blowing outward.
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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by heehaw » Sun Apr 08, 2018 3:31 pm

I am very impressed by the separation of hydrogen and oxygen, I never would have expected that! And it seems so total!

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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by neufer » Sun Apr 08, 2018 6:00 pm

heehaw wrote:
Sun Apr 08, 2018 3:31 pm

I am very impressed by the separation of hydrogen and oxygen, I never would have expected that! And it seems so total!
And the oxygen is leading the hydrogen in escaping: https://apod.nasa.gov/apod/ap121126.html

Apparently the core oxygen shoots out as (~3,000 km/s) mushroom cloud shaped jets past the outer hydrogen layer"
https://str.llnl.gov/str/BRemington.html wrote:
Supernova Hydrodynamics Up Close
by BRUCE REMINGTON


<<To examine mixing between the helium and hydrogen layers of Supernova 1987A, the most hydrodynamically unstable region of the exploding star, scientists have performed modeling studies using PROMETHEUS, a multidimensional hydrodynamics code, and the two-dimensional code CALE. They compared these simulation results with data from laser experiments that use planar foils with a tin-roof-like sinusoidal ripple to examine in two dimensions a localized region of activity. The two codes give similar results, both of which agree well with experimental results. But two-dimensional models predict maximum velocities of only about 2,000 kilometers per second for radioactive materials moving outward from the core, whereas observed velocities for these materials were actually more than 3,000 kilometers per second in Supernova 1987A. Three-dimensional hydrodynamic effects must be considered to explain these and other discrepancies between models and observations.>>
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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by Isomeme » Mon Apr 09, 2018 3:01 pm

If the supernova was visible 10,000 years ago, how can the remnant be 1,400 light-years away?

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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by Chris Peterson » Mon Apr 09, 2018 3:11 pm

Isomeme wrote:
Mon Apr 09, 2018 3:01 pm
If the supernova was visible 10,000 years ago, how can the remnant be 1,400 light-years away?
The distance to a supernova isn't relevant to when it was observed.
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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by isomeme » Mon Apr 09, 2018 5:09 pm

Ah, never mind, a thinko on my part. What this implies is that the supernova happened roughly 11,400 years ago -- 1,400 years for the light to reach Earth, and 10,000 years since then. Sorry.

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Re: APOD: NGC 6960: The Witch's Broom Nebula (2018 Apr 08)

Post by Chris Peterson » Mon Apr 09, 2018 5:18 pm

isomeme wrote:
Mon Apr 09, 2018 5:09 pm
Ah, never mind, a thinko on my part. What this implies is that the supernova happened roughly 11,400 years ago -- 1,400 years for the light to reach Earth, and 10,000 years since then. Sorry.
While that's one way to look at it, an astronomer's normal view would be that the event happened 10,000 years ago, and the distance doesn't matter.
Chris

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