An exchange of work e-mails with the spiffy
chefmayhem has reminded me to remind y'all to grab your binoculars (or telescope!) and head outside tonight!
Just two weeks ago -- on August 24th -- a Type Ia supernovae was spotted near us. Okay, it is 21,000,000 light years away, in the Pinwheel Galaxy. Still, on a cosmic scale, twenty-one million light years away is pretty near to us!
This supernova is particularly important, as it is both close to us and was spotted quite early on. Thus, it gives us a fantastic look at a Type Ia supernova in action. This type of supernova is triggered when a white dwarf in a binary star system accretes enough mass from its partner to pass the so-called Chandrasekhar limit of 1.4 solar masses. When that happens...
You get a runaway thermonuclear reaction that causes the star to explode.
Type Ia supernovae are generally all pretty similar. Thus, they are used as "standard candles" that help us to make significant comological observations; for instance, these supernovae are used to measure the expansion of the universe. Indeed, these are precisely the sort of supernovae that the Supernova Cosmology Project and the High-Z Supernova Search Team observed to discover dark energy in 1998! So making close up observations of a Type Ia will allow us to do supernova cosmology with even greater precision!
In the meantime, this particular supernovae has been getting ever-brighter over the past two weeks... and should now be at about its most intense! With a pair of good binoculars, you should be able to see it for yourself -- now there is a rare opportunity! So clear skies to you, dear friends, and happy hunting!
Notes:
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Just two weeks ago -- on August 24th -- a Type Ia supernovae was spotted near us. Okay, it is 21,000,000 light years away, in the Pinwheel Galaxy. Still, on a cosmic scale, twenty-one million light years away is pretty near to us!
This supernova is particularly important, as it is both close to us and was spotted quite early on. Thus, it gives us a fantastic look at a Type Ia supernova in action. This type of supernova is triggered when a white dwarf in a binary star system accretes enough mass from its partner to pass the so-called Chandrasekhar limit of 1.4 solar masses. When that happens...
BOOM!
You get a runaway thermonuclear reaction that causes the star to explode.
Type Ia supernovae are generally all pretty similar. Thus, they are used as "standard candles" that help us to make significant comological observations; for instance, these supernovae are used to measure the expansion of the universe. Indeed, these are precisely the sort of supernovae that the Supernova Cosmology Project and the High-Z Supernova Search Team observed to discover dark energy in 1998! So making close up observations of a Type Ia will allow us to do supernova cosmology with even greater precision!
In the meantime, this particular supernovae has been getting ever-brighter over the past two weeks... and should now be at about its most intense! With a pair of good binoculars, you should be able to see it for yourself -- now there is a rare opportunity! So clear skies to you, dear friends, and happy hunting!
Notes:
- For those who want to know more, see here, here, here, here, and here.
- Since I have already seen this misconception pop up, I should note that Type Ia supernovae explode via a very different mechanism than core collapse supernovae. It is the latter that produce neutrinos in copious numbers. Thus, even if this particular supernova was in our own galaxy, no neutrino signal would be detected in Super-Kamiokande.
- Tis excellent to have the rare opportunity to use my supernova icon for a post that is actually about supernovae! (Even if the supernova in the picture is core collapse, and not Type Ia...)
- Writing this post took up the time that was supposed to go to the promised entry on the St. Giles bells. So the bells will have to wait -- I have theatre tickets in just over an hour! That's okay, though. The bells can wait -- after all, one of them has been around for nearly four hundred years! In contrast, the supernova won't wait. After tonight, it will dim and, to our eyes, be gone.
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Obviously a man of many parts!
From:
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Not quite sure which Chandrasekhar you are thinking of, as I'm afraid that I don't follow cricket!
Whilst on the topic, I should note that "my" Chandrasekhar's uncle was Sir Chandrasekhar Raman (http://en.wikipedia.org/wiki/Sir_Chandrasekhara_Venkata_Raman), who won the Nobel Physics Prize in 1930 for work on light scattering!
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I was wondering about the difference between Type Ia and core collapse supernovae after emailing you about this one. It occurred to me that the two types must have rather different neutrino fluxes although I did not know the sense or magnitude of the difference. So there is really no hope squared of seeing a neutrino signal from this one. Alas....
From:
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Core collapse supernovae emit copious amounts of neutrinos, primarily from neutrino cooling after the hot neutron star is born. Type Ia, in contrast, work by rapid nuclear fusion of carbon. To say that the process emits no neutrinos would be incorrect... but they aren't coming out in massive quantity.
For a core collapse supernova, we really are limited to our own galaxy and its satellites for seeing supernova neutrinos. Our "canonical supernova" is near the center of the galaxy, where star density is high. That is a distance of 10 kpc; a core collapse supernova there would give us about 10,000 events in Super-Kamiokande.
Jump now to our next nearest [non-satellite] galaxy, Andromeda. At a distance of about 800 kpc, the inverse square spread of the neutrinos reduces the flux by a factor of 6400 from our canonical supernova... meaning that only one or two events will be seen. Which will not be distinguishable from background, I'm afraid. Of course, at a distance of about 7 Mpc, the Pinwheel Galaxy supernova would not get even a signal interacting neutrino event to our detector... even if it were of the core collapse type!
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I am disapointed that I will miss this event.
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Meanwhile, good luck with clear skies over the Windy City! If you would like, you and
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(When I was a kid, I wanted a reflector telescope, but the ready-made ones were far too expensive. There was a company - it may even have been Edmund Scientific (http://www.scientificsonline.com/) - that sold kits for grinding one's own reflector, including Pyrex blanks, a wax matrix, and several different grades of abrasive. You'd then send it back to them to be silvered. They'd also sell you the ancillary optical bits, and mounting parts, but you were expected to make your own tube. Even at ten years old, I could have done it, but unfortunately the kit was still more than my family could afford.)
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Over the next few years, we would start off and on to build the grinding stand and the test equipment. We never got all the require equipment together.
During High School I was the president of the Astronomy Club, and I had the school's six inch reflector every summer. Since I had a the use of the telescope the reflector kit was put aside. Since High School I been too busy to commit the time to complete the mirrors. I still have the kit untouched after forty years.
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I keep the mirror kit as a reminder that because of my dad encouragement that I have my love of science and engineering.
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