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Q & A: Supernova Remnants and Neutron Stars

SNR   Supernova Remnant (def.): The expanding glowing remains from a supernova.
Neutron Star (def.): A dense ball of neutrons that remains after a supernova has destroyed the rest of the star. Typically neutron stars are about 20km across, and contain more mass than the Sun.
Field Guide to Supernovas, Supernova Remnants & Neutron Stars
error-file:tidyout.logChandra Images: Supernovas & Supernova Remnants

Q: While looking at several "colored" photos of Tycho's supernova, I noticed a red object, at the +-11:00 o'clock position. Just wondering if this object has been observed, and/or classified?

Q: Recent writings about supernova SN2006Gy mentioned that Eta Carinae is a potential supernova candidate in our galaxy. They mentioned that at 7500 light years it would present no harm to earth if it did explode. If a supernova exploded within say 500 light years of earth what would be the consequences of such an event? Also, if Eta Carinae did explode what magnitude would it be in the night sky, give or take a bit?

Q: When will the next supernova explosion be?

Q: How bright would this glow be compared to other self luminous and reflective objects (i.e., what magnitude would it appear to be at one AU)? What how strong would this glow be in different parts of the spectrum (i.e., visible light, IR, etc.)?

Q: Concerning magnetars: when their magnetic field causes them to slow down, do they become pulsars for a time before becoming a regular neutron star or do they go straight from a magnatar to a neutron star? Also, I have heard some references that claim neutron stars that are not part of a multiple star system and are not accreting matter sometimes explode as supernovas. Is this true or do they just exist as a stable silent lump of neutrons with a solid crust of iron nuclei forever?

Q: Does the (W) stand for anything in W49B?

Q: Why do neutron stars have strong magnetic fields?

Q: The image you have posted of the Kepler SNR is said to be 14ly in diameter and expanding at 2 million meters per second. Is the rate of expansion slowing or has it slowed since the SN event? Is the rate constant since the event? What was the speed of expansion at the start of the event?

Q: The Cassiopeia A pictures are very interesting. Is there an estimate of the mass and density of the stuff in the 10 light year diameter surounding the supernova event? And is that stuff mostly silicon or a mix of elements such as is found in clouds?

Q: I saw the photo of the remnants of Cassiopeia A which exploded some 300 years ago (from our frame of reference). How can the gases still be at 50 million degrees? Wouldn't the density of the gas have decreased to a point that the temperature dropped significantly?

Q: How long do we have before the Sun goes supernova and frys us? Supposing this does happen, are any other planets capable of maintaining human life?

Q: What country has the best astronomical records of the Great Supernova of 1054 AD?

Q: Is there a pulsar in the SN1987A?

Q: In your web page on "Supernovas and Remnants", you show that a star would be a blue supergiant before it explodes as a supernova. However, in the web page on "Birth of a Neutron Star and Supernova Remnant", you show that the pre-supernova star is a red supergiant. So, which is correct?

Q: Has anyone been able to determine what is at the center of Supernova remnant 1987A?

Q: Can you please tell me what is the blue dot located at approximately 8 o'clock to the supernova remnant?

Q: In Chandra Digest G54.1, reference is made to "a disc of matter and antimatter" surrounding SNR G54.1+ 03.How is mutual annihilation avoided?

Q: Is there is a diameter calculated for the size of the neutron star?

Q: Does Chandra register something about the magnetars?

Q: Since these huge stars are prone to collapse, wouldn't it seem to perfectly plausible that a good majority of these stars have already collapsed. Especially ones that are multiple times bigger than ones we know of?

Q: I note that there are at least 3 "waves" that pass the distance between the 2 rings in 6 months time. Wouldn't that mean that the waves would be traveling at least 2 C if not faster?

Q: In the Crab Nebula Movie, why do some of the background stars appear to blink? Is this an artifact of the encoding or are they variables?

Q: I viewed the "Time-Lapse Movie Of Crab Pulsar Wind"... Is the sequence a series of replayed shorter image sequences or is each frame displaying an image taken at a later time?

Q: The article says that 3C58 is cooler than expected, so it is thought it could be denser than a normal neutron star. Why would something more dense be cooler?

Q: Do neutron stars decay?

Q: What are five differences between white dwarfs and neutron stars?

Q: An article I read says a pulsar is 1,615 years old - the Chinese saw something 1,600 years ago.. Doesn't that mean that what the Chinese saw in the sky was an event that took place at least 15,000 years ago?

Q: Where in the galaxy would you expect to find Type I and Type II supernovas?

Q: I am wondering if there is a discovery of neutron star that wasn't detected by radio pulsation. If there is, do you know an example of such star and such detection?

Q: I was reading from the ABC Science site that the diameter of the Cas A gas cloud is 10 light years and the event occurred 300 years ago. That would mean that this gas cloud is moving at a rate of close to a tenth of the speed of light. Is that true?

Q: Hi, I read the article "Impact! Chandra Images a Young Supernova Blast Wave" and have just one question. Will that blast affect us (on Earth)?

Q: Do you think that our galaxy has supernova remnants like the Crab Nebula in places that Chandra is incapable of seeing?

Q: Has there been substantial success in situations where historical observations (such as the 320 year old report that may have been Cas-A) have been observed (or their remains observed)? Do you happen to know of a link to follow that might have information about older reports of a similar nature?

Q: Are there any nearby stars that could explode and threaten our existence?

Q: I saw a photo designated Cas A that is labeled as a 320 year old event from a location 10,000 light years away. I was wondering how the event could have happened 320 years ago and the radiation that produced the image arrive in time for me to view it. Have I misread the caption?

Q: Are Tychos SNR and Cygnus A /other strong double radio galaxies likely targets in the near future?

Q: What is the size of, X-ray energy of and exposure time of the image of the Crab Nebula? 2) What is the presumed orientation of the X-ray image versus that of the pulsar?

Q: I still don't understand the fact that all that photos show something expanding in a "circular/planar" situation and not in a "spherical/3D" configuration. Could that be that the circular expansion is a concentration of a spherical explosion seeing sideways - a mere optical effect?

Q: Can you tell me which direction, or toward what other constellation or deep sky object, the apparent cross bow in the Vela pulsar points?

Q: Is Cassiopeia A in our Galaxy ?

Q: Is there any known star that has the apparent dimensions of the depicted mystery object on which we voted at

Q&A Index