APOD: The Crab from Space (2018 Mar 17)

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APOD: The Crab from Space (2018 Mar 17)

Post by APOD Robot » Sat Mar 17, 2018 4:09 am

Image The Crab from Space

Explanation: The Crab Nebula is cataloged as M1, the first object on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, expanding debris from the death explosion of a massive star. This intriguing false-color image combines data from space-based observatories, Chandra, Hubble, and Spitzer, to explore the debris cloud in X-rays (blue-white), optical (purple), and infrared (pink) light. One of the most exotic objects known to modern astronomers, the Crab Pulsar, a neutron star spinning 30 times a second, is the bright spot near picture 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 6,500 light-years away in the constellation Taurus.

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Ann » Sat Mar 17, 2018 9:31 am

Crab Nebula.
NASA/CXC/SAO/F.Seward et al






























Any idea what causes the apparent asymmetry of the crab? The appears to be a "jet" of some sort "spilling out" of the area immediately adjacent to the left of the pulsar in today's APOD, but nothing (obviously) similar is seen to the right.

Can't help thinking of giant elliptical galaxy M87, which also apparently produces just one jet launched from the vicinity of its supermassive black hole.

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Sa Ji Tario » Sat Mar 17, 2018 1:15 pm

An emission of the first times in which the electromagnetic emission of the pulsar was translated by electronic means into the audible frequency, the sound similar to that of the child

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by neufer » Sat Mar 17, 2018 1:34 pm


Ann wrote:
Sat Mar 17, 2018 9:31 am

Any idea what causes the apparent asymmetry of the crab? The appears to be a "jet" of some sort "spilling out" of the area immediately adjacent to the left of the pulsar in today's APOD, but nothing (obviously) similar is seen to the right.
It asymmetrical interaction with the ISM :?:
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Re: APOD: The Crab from Space (2018 Mar 17)

Post by heehaw » Sat Mar 17, 2018 1:51 pm

What a time to be alive! When I went off to graduate school in 1962, Professor Sidney van den Bergh (Toronto) told me that half of what we know about astronomy we have learned from the Crab nebula: that was before the discovery (1968) of the pulsar even!

NCTom

Re: APOD: The Crab from Space (2018 Mar 17)

Post by NCTom » Sat Mar 17, 2018 1:53 pm

From reading what Wikipedia says about the death of a neutron star - a cold orb or a very small black hole, these things could be everywhere and if we ever find a way to detect them and study them, they could be used as a possible gauge for the age of our galaxy if not the universe.

sunson

Re: APOD: The Crab from Space (2018 Mar 17)

Post by sunson » Sat Mar 17, 2018 2:08 pm

What would be +/- the diameter of the neutron star?

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Chris Peterson » Sat Mar 17, 2018 2:17 pm

sunson wrote:
Sat Mar 17, 2018 2:08 pm
What would be +/- the diameter of the neutron star?
Around 10 km. Not unlike the size of a comet in our own system.
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Re: APOD: The Crab from Space (2018 Mar 17)

Post by bystander » Sat Mar 17, 2018 2:20 pm

Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Chris Peterson » Sat Mar 17, 2018 2:22 pm

NCTom wrote:
Sat Mar 17, 2018 1:53 pm
From reading what Wikipedia says about the death of a neutron star - a cold orb or a very small black hole, these things could be everywhere and if we ever find a way to detect them and study them, they could be used as a possible gauge for the age of our galaxy if not the universe.
Neutron stars represent a stable endpoint. They do not ever become black holes unless something falls onto them and increases their mass- a very rare event. Otherwise, they just slowly cool.

Stellar mass black holes (that is, ordinary black holes) are certainly common, but aren't useful for looking at the age of the Universe, because these black holes form from the collapse of massive stars not long after those stars form- a process which has been going on since the beginning.
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Re: APOD: The Crab from Space (2018 Mar 17)

Post by neufer » Sat Mar 17, 2018 3:11 pm

neufer wrote:
Sat Mar 17, 2018 1:34 pm

Ann wrote:
Sat Mar 17, 2018 9:31 am

Any idea what causes the apparent asymmetry of the crab? The appears to be a "jet" of some sort "spilling out" of the area immediately adjacent to the left of the pulsar in today's APOD, but nothing (obviously) similar is seen to the right.
It asymmetrical interaction with the ISM :?:
https://en.wikipedia.org/wiki/Supernova#Asymmetry wrote: <<A long-standing puzzle surrounding Type II supernovae is why the remaining compact object receives a large velocity away from the epicentre; pulsars, and thus neutron stars, are observed to have high velocities, and black holes presumably do as well, although they are far harder to observe in isolation. The initial impetus can be substantial, propelling an object of more than a solar mass at a velocity of 500 km/s or greater. This indicates an expansion asymmetry, but the mechanism by which momentum is transferred to the compact object remains a puzzle. Proposed explanations for this kick include convection in the collapsing star and jet production during neutron star formation.

One possible explanation for this asymmetry is a large-scale convection above the core. The convection can create variations in the local abundances of elements, resulting in uneven nuclear burning during the collapse, bounce and resulting expansion.

Another possible explanation is that accretion of gas onto the central neutron star can create a disk that drives highly directional jets, propelling matter at a high velocity out of the star, and driving transverse shocks that completely disrupt the star. These jets might play a crucial role in the resulting supernova. (A similar model is now favored for explaining long gamma-ray bursts.)

Initial asymmetries have also been confirmed in Type Ia supernovae through observation. This result may mean that the initial luminosity of this type of supernova depends on the viewing angle. However, the expansion becomes more symmetrical with the passage of time. Early asymmetries are detectable by measuring the polarization of the emitted light.>>
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Re: APOD: The Crab from Space (2018 Mar 17)

Post by neufer » Sat Mar 17, 2018 3:24 pm

Chris Peterson wrote:
Sat Mar 17, 2018 2:22 pm
NCTom wrote:
Sat Mar 17, 2018 1:53 pm

From reading what Wikipedia says about the death of a neutron star - a cold orb or a very small black hole, these things could be everywhere and if we ever find a way to detect them and study them, they could be used as a possible gauge for the age of our galaxy if not the universe.
Neutron stars represent a stable endpoint. They do not ever become black holes unless something falls onto them and increases their mass- a very rare event. Otherwise, they just slowly cool.
https://en.wikipedia.org/wiki/Neutron_star#Formation wrote:
<<Neutron stars in binary systems can undergo accretion which typically makes the system bright in X-rays while the material falling onto the neutron star can form hotspots that rotate in and out of view in identified X-ray pulsar systems. Additionally, such accretion can "recycle" old pulsars and potentially cause them to gain mass and spin-up to very fast rotation rates, forming the so-called millisecond pulsars. These binary systems will continue to evolve, and eventually the companions can become compact objects such as white dwarfs or neutron stars themselves, though other possibilities include a complete destruction of the companion through ablation or merger. The merger of binary neutron stars may be the source of short-duration gamma-ray bursts and are likely strong sources of gravitational waves. In 2017, a direct detection (GW170817) of the gravitational waves from such an event was made, and gravitational waves have also been indirectly detected in a system where two neutron stars orbit each other.

About 5% of all known neutron stars are members of a binary system. The formation and evolution of binary neutron stars can be a complex process. Neutron stars have been observed in binaries with ordinary main-sequence stars, red giants, white dwarfs or other neutron stars. According to modern theories of binary evolution it is expected that neutron stars also exist in binary systems with black hole companions. The merger of binaries containing two neutron stars, or a neutron star and a black hole, are expected to be prime sources for the emission of detectable gravitational waves.

Binary systems containing neutron stars often emit X-rays, which are emitted by hot gas as it falls towards the surface of the neutron star. The source of the gas is the companion star, the outer layers of which can be stripped off by the gravitational force of the neutron star if the two stars are sufficiently close. As the neutron star accretes this gas its mass can increase; if enough mass is accreted the neutron star may collapse into a black hole.

Binaries containing two neutron stars are observed to shrink as gravitational waves are emitted. Ultimately the neutron stars will come into contact and coalesce. The coalescence of binary neutron stars is one of the leading models for the origin of short gamma-ray bursts. Strong evidence for this model came from the observation of a kilonova associated with the short-duration gamma-ray burst GRB 130603B, and finally confirmed by detection of gravitational wave GW170817 and short GRB 170817A by LIGO, Virgo and 70 observatories covering the electromagnetic spectrum observed the event. The light emitted in the kilonova is believed to come from the radioactive decay of material ejected in the merger of the two neutron stars. This material may be responsible for the production of many of the chemical elements beyond iron, as opposed to the supernova nucleosynthesis theory.>>
Art Neuendorffer

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Chris Peterson » Sat Mar 17, 2018 3:28 pm

neufer wrote:
Sat Mar 17, 2018 3:24 pm
Chris Peterson wrote:
Sat Mar 17, 2018 2:22 pm
Neutron stars represent a stable endpoint. They do not ever become black holes unless something falls onto them and increases their mass- a very rare event. Otherwise, they just slowly cool.
https://en.wikipedia.org/wiki/Neutron_star#Formation wrote:
<<Neutron stars in binary systems can undergo accretion which typically makes the system bright in X-rays while the material falling onto the neutron star can form hotspots that rotate in and out of view in identified X-ray pulsar systems...
Indeed. The salient point, of course, being that an outside mechanism is required to add mass to a neutron star.
Chris

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by neufer » Sat Mar 17, 2018 4:05 pm

Chris Peterson wrote:
Sat Mar 17, 2018 3:28 pm
neufer wrote:
Sat Mar 17, 2018 3:24 pm
Chris Peterson wrote:
Sat Mar 17, 2018 2:22 pm

Neutron stars represent a stable endpoint. They do not ever become black holes unless something falls onto them
and increases their mass- a very rare event. Otherwise, they just slowly cool.
https://en.wikipedia.org/wiki/Neutron_star#Formation wrote:
<<Neutron stars in binary systems can undergo accretion which typically makes the system bright in X-rays while the material falling onto the neutron star can form hotspots that rotate in and out of view in identified X-ray pulsar systems...
Indeed. The salient point, of course, being that an outside mechanism is required to add mass to a neutron star.
If "about 5% of all known neutron stars are members of a binary system"
should it be classified as a very rare event :?:
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Re: APOD: The Crab from Space (2018 Mar 17)

Post by ta152h0 » Sat Mar 17, 2018 4:14 pm

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Chris Peterson » Sat Mar 17, 2018 4:33 pm

neufer wrote:
Sat Mar 17, 2018 4:05 pm
Chris Peterson wrote:
Sat Mar 17, 2018 3:28 pm
neufer wrote:
Sat Mar 17, 2018 3:24 pm
Indeed. The salient point, of course, being that an outside mechanism is required to add mass to a neutron star.
If "about 5% of all known neutron stars are members of a binary system"
should it be classified as a very rare event :?:
I would. But the discussion wasn't really about binary systems. It was about how neutron stars evolve. They never evolve into black holes.
Chris

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by De58te » Sat Mar 17, 2018 4:41 pm

Ann wrote:
Sat Mar 17, 2018 9:31 am
Any idea what causes the apparent asymmetry of the crab?
My layman theory is that the Big Bang created equal amounts of matter and anti-matter, but they got separated early on during the expansion, or else they would annihilate each other and there would be nothing in the universe. It could just so happen that a nearby anti-matter planet system or an anti-matter nebula was happily coexisting on the left side of the Crab star for billions of years until the supernova explosion. Then the charged particles spread out on the left just like on the right, but the particles collided with anti-matter and annihilated. Now what we see with the jet means that all the anti-matter had disappeared and so the jet can now start expanding but is way behind the right side.

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Chris Peterson » Sat Mar 17, 2018 4:47 pm

De58te wrote:
Sat Mar 17, 2018 4:41 pm
Ann wrote:
Sat Mar 17, 2018 9:31 am
Any idea what causes the apparent asymmetry of the crab?
My layman theory is that the Big Bang created equal amounts of matter and anti-matter, but they got separated early on during the expansion, or else they would annihilate each other and there would be nothing in the universe. It could just so happen that a nearby anti-matter planet system or an anti-matter nebula was happily coexisting on the left side of the Crab star for billions of years until the supernova explosion. Then the charged particles spread out on the left just like on the right, but the particles collided with anti-matter and annihilated. Now what we see with the jet means that all the anti-matter had disappeared and so the jet can now start expanding but is way behind the right side.
There can't be any antimatter bodies of much greater than single particle mass around, or they'd be obvious just from their interaction with the thin interstellar medium.

The prevailing theory is that there was a tiny, tiny imbalance between the amount of matter and antimatter after the Big Bang, and the result was that all the antimatter (and most of the initial matter) was annihilated and we're left only with ordinary matter.
Chris

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Ann » Sat Mar 17, 2018 5:38 pm

NCTom wrote:
Sat Mar 17, 2018 1:53 pm
From reading what Wikipedia says about the death of a neutron star - a cold orb or a very small black hole, these things could be everywhere and if we ever find a way to detect them and study them, they could be used as a possible gauge for the age of our galaxy if not the universe.
Like others have pointed out, a neutron star doesn't just collapse into a black hole. But it will keep losing heat into the surrounding medium. Eventually it should indeed be cold.

Ann
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Re: APOD: The Crab from Space (2018 Mar 17)

Post by NoSnakesHere » Sat Mar 17, 2018 6:20 pm

Chris Peterson wrote:
Sat Mar 17, 2018 4:47 pm
De58te wrote:
Sat Mar 17, 2018 4:41 pm
Ann wrote:
Sat Mar 17, 2018 9:31 am
Any idea what causes the apparent asymmetry of the crab?
My layman theory is that the Big Bang created equal amounts of matter and anti-matter, but they got separated early on during the expansion, or else they would annihilate each other and there would be nothing in the universe. It could just so happen that a nearby anti-matter planet system or an anti-matter nebula was happily coexisting on the left side of the Crab star for billions of years until the supernova explosion. Then the charged particles spread out on the left just like on the right, but the particles collided with anti-matter and annihilated. Now what we see with the jet means that all the anti-matter had disappeared and so the jet can now start expanding but is way behind the right side.
There can't be any antimatter bodies of much greater than single particle mass around, or they'd be obvious just from their interaction with the thin interstellar medium.

The prevailing theory is that there was a tiny, tiny imbalance between the amount of matter and antimatter after the Big Bang, and the result was that all the antimatter (and most of the initial matter) was annihilated and we're left only with ordinary matter.
And then the unseen, unsuspected thing jumped out and said, "BOOOOOOOOOOOOOOOOOOOOOOOOOOOOOm3" Happy St. Patrick's Day.

Sa Ji Tario

Re: APOD: The Crab from Space (2018 Mar 17)

Post by Sa Ji Tario » Sun Mar 18, 2018 6:41 am

¿Alguien me puede definir el término ISM?

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by geckzilla » Sun Mar 18, 2018 7:19 am

Sa Ji Tario wrote:
Sun Mar 18, 2018 6:41 am
¿Alguien me puede definir el término ISM?
https://es.wikipedia.org/wiki/Medio_interestelar
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: The Crab from Space (2018 Mar 17)

Post by Sa Ji Tario » Sun Mar 18, 2018 4:15 pm

Gracias geck, la busqué como ISM pero en español está como "Materia interestelar"