APOD: M1: The Crab Nebula (2021 Dec 24)

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APOD: M1: The Crab Nebula (2021 Dec 24)

Post by APOD Robot » Fri Dec 24, 2021 5:05 am

Image M1: The Crab Nebula

Explanation: The Crab Nebula is cataloged as M1, the first object on Charles Messier's famous 18th century list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, debris from the death explosion of a massive star, witnessed by astronomers in the year 1054. This sharp, ground-based telescopic view combines broadband color data with narrowband data that tracks emission from ionized sulfur, hydrogen, and oxygen atoms to explore the tangled filaments within the still expanding cloud. One of the most exotic objects known to modern astronomers, the Crab Pulsar, a neutron star spinning 30 times a second, is visible as a bright spot near the nebula's center. Like a cosmic dynamo, this collapsed remnant of the stellar core powers the Crab's emission across the electromagnetic spectrum. Spanning about 12 light-years, the Crab Nebula is a mere 6,500 light-years away in the constellation Taurus.

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RocketRon

Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by RocketRon » Fri Dec 24, 2021 6:21 am

It was a tremendous explosion, wasn't it !
And a magnificent photo opportunity.
Not to mention a firing up of scientific knowledge,
way before it was understood what it was.

Would 12 light years have engulfed any nearby stars ?
And what would be the effect ?
Would they even notice ?

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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by VictorBorun » Fri Dec 24, 2021 9:11 am

and why is the Crab so complicated?
Why cannot we see just a pair of long jets along the axis of the "neutron star spinning 30 times a second" and some disk of a less radius in the equatorial plane?

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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by VictorBorun » Fri Dec 24, 2021 9:20 am

RocketRon wrote: Fri Dec 24, 2021 6:21 am Would 12 light years have engulfed any nearby stars ?
well 6,500 light-years away is well within GAIA's ranging capability, isn't it?
The star field in the picture must all be 3d mapped or attributed to far background

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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by orin stepanek » Fri Dec 24, 2021 12:47 pm

🤶🏻 🧑🏻🎄 🎅🏻 Have a great Christmas Eve!
Sherick_M1_SHOLRGB_12-5-21a.jpg
Beautiful not a comet! M1 :lol2: Thank you Charles for your catalog of
not comets! 8-)
crab_lg1024.jpg
Beautiful color assigned to the crab's pulsar! 8-)
'
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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by neufer » Fri Dec 24, 2021 2:15 pm

Click to play embedded YouTube video.
VictorBorun wrote: Fri Dec 24, 2021 9:11 am
and why is the Crab so complicated?

Why cannot we see just a pair of long jets along the axis of the "neutron star spinning 30 times a second" and some disk of a less radius in the equatorial plane?
Art Neuendorffer

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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by Chris Peterson » Fri Dec 24, 2021 2:53 pm

RocketRon wrote: Fri Dec 24, 2021 6:21 am Would 12 light years have engulfed any nearby stars ?
And what would be the effect ?
Would they even notice ?
The nebula probably encloses other stars. Anybody on those stars would have certainly experienced effects from the supernova. But the expanding nebula, from the inside, would just make the background sky a little bit lighter. It might not be noticed. At the least, there would probably be nothing obvious about it. A civilization advanced enough to be paying attention to the sky, however, would probably observe the sky changing over just a few hundred years.
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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by neufer » Fri Dec 24, 2021 3:36 pm

Chris Peterson wrote: Fri Dec 24, 2021 2:53 pm
RocketRon wrote: Fri Dec 24, 2021 6:21 am
Would 12 light years [wide] have engulfed any nearby stars ?
And what would be the effect ?
Would they even notice ?
The nebula probably encloses other stars. Anybody on those stars would have certainly experienced effects from the supernova. But the expanding nebula, from the inside, would just make the background sky a little bit lighter. It might not be noticed. At the least, there would probably be nothing obvious about it. A civilization advanced enough to be paying attention to the sky, however, would probably observe the sky changing over just a few hundred years.
https://en.wikipedia.org/wiki/Near-Earth_supernova wrote:
<<A near-Earth supernova is an explosion resulting from the death of a star that occurs close enough to the Earth (roughly less than 10 to 300 parsecs (30 to 1000 light-years) away) to have noticeable effects on Earth's biosphere. Gamma ray bursts from "dangerously close" supernova explosions occur two or more times per billion years, and this has been proposed as the cause of the end Ordovician extinction, which resulted in the death of nearly 60% of the oceanic life on Earth. A.L. Melott, suggested that the Ordovician extinction could have been caused by a gamma-ray burst originating from a hypernova in a nearby arm of the Milky Way galaxy, within 6,000 light-years of Earth. A ten-second burst would have stripped the Earth's atmosphere of half of its ozone almost immediately, exposing surface-dwelling organisms, including those responsible for planetary photosynthesis, to high levels of extreme ultraviolet radiation. Under this hypothesis, several groups of marine organisms with a planktonic lifestyle were more exposed to UV radiation than groups that lived on the seabed. This is consistent with observations that planktonic organisms suffered severely during the first extinction pulse. In addition, species dwelling in shallow water were more likely to become extinct than species dwelling in deep water. A gamma-ray burst could also explain the rapid onset of glaciation, since ozone and nitrogen would react to form nitrogen dioxide, a darkly-colored aerosol which cools the earth.

It is estimated that a Type II supernova closer than eight parsecs (26 light-years) would destroy more than half of the Earth's ozone layer. Such estimates are based on atmospheric modeling and the measured radiation flux from SN 1987A, a Type II supernova in the Large Magellanic Cloud. Estimates of the rate of supernova occurrence within 10 parsecs of the Earth vary from 0.05–0.5 per billion years to 10 per billion years. Several studies assume that supernovae are concentrated in the spiral arms of the galaxy, and that supernova explosions near the Sun usually occur during the approximately 10 million years that the Sun takes to pass through one of these regions.Examples of relatively near supernovae are the Vela Supernova Remnant (c. 800 ly, c. 12,000 years ago) and Geminga (c. 550 ly, c. 300,000 years ago).

Historically, each near-Earth supernova explosion has been associated with a global warming of around 3–4 °C. An estimated 20 supernova explosions have happened within 300 pc of the Earth over the last 11 million years. On average, a supernova explosion occurs within 10 parsecs (33 light-years) of the Earth every 240 million years. Gamma rays are responsible for most of the adverse effects that a supernova can have on a living terrestrial planet. In Earth's case, gamma rays induce radiolysis of diatomic N2 and O2 in the upper atmosphere, converting molecular nitrogen and oxygen into nitrogen oxides, depleting the ozone layer enough to expose the surface to harmful solar and cosmic radiation (mainly ultra-violet). Phytoplankton and reef communities would be particularly affected, which could severely deplete the base of the marine food chain.

In 1998 a supernova remnant, RX J0852.0-4622, was found in front (apparently) of the larger Vela Supernova Remnant. Gamma rays from the decay of titanium-44 (half-life about 60 years) were independently discovered emanating from it, showing that it must have exploded fairly recently (perhaps around the year 1200), but there is no historical record of it. The flux of gamma rays and X-rays indicates that the supernova was relatively close to us (perhaps 200 parsecs or 660 ly). If so, this is an unexpected event because supernovae less than 200 parsecs away are estimated to occur less than once per 100,000 years.

Evidence from daughter products of short-lived radioactive isotopes shows that a nearby supernova helped determine the composition of the Solar System 4.5 billion years ago, and may even have triggered the formation of this system. Supernova production of heavy elements over astronomic periods of time ultimately made the chemistry of life on Earth possible.

Past supernovae might be detectable on Earth in the form of metal isotope signatures in rock strata. Subsequently, iron-60 enrichment has been reported in deep-sea rock of the Pacific Ocean by researchers from the Technical University of Munich. Twenty-three atoms of this iron isotope were found in the top 2 cm of crust (this layer corresponds to times from 13.4 million years ago to the present). It is estimated that the supernova must have occurred in the last 5 million years or else it would have had to happen very close to the solar system to account for so much iron-60 still being here. A supernova occurring so close would have probably caused a mass extinction, which did not happen in that time frame. The quantity of iron seems to indicate that the supernova was less than 30 parsecs away. On the other hand, the authors estimate the frequency of supernovae at a distance less than D (for reasonably small D) as around (D/10 pc)3 per billion years, which gives a probability of only around 5% for a supernova within 30 pc in the last 5 million years. They point out that the probability may be higher because the Solar System is entering the Orion Arm of the Milky Way. In 2019, the group in Munich found interstellar dust in Antarctic surface snow not older than 20 years which they relate to the Local Interstellar Cloud. The detection of interstellar dust in Antarctica was done by the measurement of the radionuclides Fe-60 and Mn-53 by highly sensitive Accelerator mass spectrometry, where Fe-60 is again the clear signature for a recent near-Earth supernova origin.>>
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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by johnnydeep » Fri Dec 24, 2021 10:18 pm

Chris Peterson wrote: Fri Dec 24, 2021 2:53 pm
RocketRon wrote: Fri Dec 24, 2021 6:21 am Would 12 light years have engulfed any nearby stars ?
And what would be the effect ?
Would they even notice ?
The nebula probably encloses other stars. Anybody on those stars would have certainly experienced effects from the supernova. But the expanding nebula, from the inside, would just make the background sky a little bit lighter. It might not be noticed. At the least, there would probably be nothing obvious about it. A civilization advanced enough to be paying attention to the sky, however, would probably observe the sky changing over just a few hundred years.
Would you believe that after more than two years of reading posts here, it finally dawned on me what a hilariously ironic name Cloudbait Observatory is?! How clever to set up very low expectations that are sure to be exceeded in practice.
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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by Chris Peterson » Fri Dec 24, 2021 10:57 pm

johnnydeep wrote: Fri Dec 24, 2021 10:18 pm
Chris Peterson wrote: Fri Dec 24, 2021 2:53 pm
RocketRon wrote: Fri Dec 24, 2021 6:21 am Would 12 light years have engulfed any nearby stars ?
And what would be the effect ?
Would they even notice ?
The nebula probably encloses other stars. Anybody on those stars would have certainly experienced effects from the supernova. But the expanding nebula, from the inside, would just make the background sky a little bit lighter. It might not be noticed. At the least, there would probably be nothing obvious about it. A civilization advanced enough to be paying attention to the sky, however, would probably observe the sky changing over just a few hundred years.
Would you believe that after more than two years of reading posts here, it finally dawned on me what a hilariously ironic name Cloudbait Observatory is?! How clever to set up very low expectations that are sure to be exceeded in practice.
If you're going to laugh at the gods, do it loudly and boldly!
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Sa Ji Tario

Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by Sa Ji Tario » Sat Dec 25, 2021 12:00 am

Peace and happiness tonight. Orion will be culminating when we raise our glasses

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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by VictorBorun » Sat Dec 25, 2021 12:18 am

neufer wrote: Fri Dec 24, 2021 2:15 pm
Click to play embedded YouTube video.
VictorBorun wrote: Fri Dec 24, 2021 9:11 am
and why is the Crab so complicated?

Why cannot we see just a pair of long jets along the axis of the "neutron star spinning 30 times a second" and some disk of a less radius in the equatorial plane?
great 3d model, thanks

So this APOD is all about the oblong outer shell, and looks complex because it is transparent and full of filaments.
It would be natural to guess that those filaments were made by unwinding the numerous magnetic whirls present in the star at the start of the Super Nova explosion, would not it?

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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by VictorBorun » Sat Dec 25, 2021 3:43 am

neufer wrote: Fri Dec 24, 2021 2:15 pm
Click to play embedded YouTube video.
VictorBorun wrote: Fri Dec 24, 2021 9:11 am
and why is the Crab so complicated?

Why cannot we see just a pair of long jets along the axis of the "neutron star spinning 30 times a second" and some disk of a less radius in the equatorial plane?
I think one can make a transparent christmas tree ball into such thing that from every angle seems dense at its ridge and see-through in the middle. You need to find some curly woollen yarn, cut a length about 1/2 of the ball's radius and just paste the wool all over, baldishly

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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by beryllium732 » Sun Dec 26, 2021 1:34 am

I don't see the pulsar. There's several bright spots.

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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by neufer » Sun Dec 26, 2021 2:56 am

beryllium732 wrote: Sun Dec 26, 2021 1:34 am
I don't see the pulsar. There's several bright spots.
  • It's the bright spot blinking 30 times a second:
NASA/CXC/Penn State/K.Mori et al. - http://chandra.harvard.edu/photo/2004/titan/ wrote:
Click to play embedded YouTube video.

<<On January 5, 2003, Titan — Saturn's largest moon and the only moon in the solar system with a thick atmosphere — crossed in front of the Crab Nebula, a bright, extended X-ray source. Titan's transit enabled Chandra to image the one-arcsecond-diameter X-ray shadow cast by the moon (inset). This tiny shadow corresponds to the size of a dime as viewed from about two and a half miles.

The diameter of Titan's shadow was found to be larger than the known diameter of its solid surface. This difference in diameters yields a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere.

The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may have caused its atmosphere to expand.

Although Titan passes within a few degrees of the Crab Nebula every 30 years, it rarely passes directly in front of it. This may have been the first transit of the Crab Nebula by Titan since the nebula was formed by a supernova that was observed to occur in the year 1054. The next similar conjunction will take place in the year 2267, so this was truly a once in a millennium event.>>
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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by alter-ego » Sun Dec 26, 2021 4:12 am

beryllium732 wrote: Sun Dec 26, 2021 1:34 am I don't see the pulsar. There's several bright spots.
Crab pulsar, V* CM Tau, indicated.
 
V[star] CM Tau -- Pulsar.jpg
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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by johnnydeep » Sun Dec 26, 2021 12:02 pm

neufer wrote: Sun Dec 26, 2021 2:56 am
beryllium732 wrote: Sun Dec 26, 2021 1:34 am
I don't see the pulsar. There's several bright spots.
  • It's the bright spot blinking 30 times a second:
NASA/CXC/Penn State/K.Mori et al. - http://chandra.harvard.edu/photo/2004/titan/ wrote:
Click to play embedded YouTube video.

<<On January 5, 2003, Titan — Saturn's largest moon and the only moon in the solar system with a thick atmosphere — crossed in front of the Crab Nebula, a bright, extended X-ray source. Titan's transit enabled Chandra to image the one-arcsecond-diameter X-ray shadow cast by the moon (inset). This tiny shadow corresponds to the size of a dime as viewed from about two and a half miles.

The diameter of Titan's shadow was found to be larger than the known diameter of its solid surface. This difference in diameters yields a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere.

The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may have caused its atmosphere to expand.

Although Titan passes within a few degrees of the Crab Nebula every 30 years, it rarely passes directly in front of it. This may have been the first transit of the Crab Nebula by Titan since the nebula was formed by a supernova that was observed to occur in the year 1054. The next similar conjunction will take place in the year 2267, so this was truly a once in a millennium event.>>
I don’t get it. Why doesn’t Titan’s indicated path seem to transit the pulsar in that pic? It appears to miss it by at least 8 arc seconds.
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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by Chris Peterson » Sun Dec 26, 2021 2:14 pm

johnnydeep wrote: Sun Dec 26, 2021 12:02 pm
neufer wrote: Sun Dec 26, 2021 2:56 am
beryllium732 wrote: Sun Dec 26, 2021 1:34 am
I don't see the pulsar. There's several bright spots.
  • It's the bright spot blinking 30 times a second:
NASA/CXC/Penn State/K.Mori et al. - http://chandra.harvard.edu/photo/2004/titan/ wrote:
Click to play embedded YouTube video.

<<On January 5, 2003, Titan — Saturn's largest moon and the only moon in the solar system with a thick atmosphere — crossed in front of the Crab Nebula, a bright, extended X-ray source. Titan's transit enabled Chandra to image the one-arcsecond-diameter X-ray shadow cast by the moon (inset). This tiny shadow corresponds to the size of a dime as viewed from about two and a half miles.

The diameter of Titan's shadow was found to be larger than the known diameter of its solid surface. This difference in diameters yields a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere.

The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may have caused its atmosphere to expand.

Although Titan passes within a few degrees of the Crab Nebula every 30 years, it rarely passes directly in front of it. This may have been the first transit of the Crab Nebula by Titan since the nebula was formed by a supernova that was observed to occur in the year 1054. The next similar conjunction will take place in the year 2267, so this was truly a once in a millennium event.>>
I don’t get it. Why doesn’t Titan’s indicated path seem to transit the pulsar in that pic? It appears to miss it by at least 8 arc seconds.
It didn't transit the pulsar. It transited the nebula.
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Re: APOD: M1: The Crab Nebula (2021 Dec 24)

Post by johnnydeep » Sun Dec 26, 2021 3:27 pm

Chris Peterson wrote: Sun Dec 26, 2021 2:14 pm
johnnydeep wrote: Sun Dec 26, 2021 12:02 pm
neufer wrote: Sun Dec 26, 2021 2:56 am
  • It's the bright spot blinking 30 times a second:
I don’t get it. Why doesn’t Titan’s indicated path seem to transit the pulsar in that pic? It appears to miss it by at least 8 arc seconds.
It didn't transit the pulsar. It transited the nebula.
Ok, got it. For some reason I was thinking that only the pulsar itself was emitting x-rays, but I see now from the text that the whole nebula does (or at least a good part of it surrounding the pulsar).
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