An exchange of work e-mails with the spiffy [livejournal.com profile] 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...

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:
  1. For those who want to know more, see here, here, here, here, and here.

  2. 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.

  3. 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...)

  4. 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.

From: [identity profile] cmcmck.livejournal.com


And there was me thinking that Chandrasekhar was a famous Indian cricketer :o)

Obviously a man of many parts!

From: [identity profile] anarchist-nomad.livejournal.com


*laughs* I was thinking of Subrahmanyan_Chandrasekhar (http://en.wikipedia.org/wiki/Subrahmanyan_Chandrasekhar), who predicted an upper limit on the mass of a stable white dwarf star in 1930... and won the Nobel Physics Prize for this work in 1983 (over fifty years later!).

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!
Edited Date: 2011-09-10 08:17 am (UTC)

From: [identity profile] gyades.livejournal.com


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.

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: [identity profile] anarchist-nomad.livejournal.com


Yes, exactly. "No hope squared" is an excellent way of putting it!

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!

From: [identity profile] xirpha.livejournal.com


Mag 10 is really not visable even with a good pair of binolocar anywhere near Chicago. Even with a good small telescope it wouild be very hard to find. It does not help that it is cloudly everywhere.

I am disapointed that I will miss this event.

From: [identity profile] anarchist-nomad.livejournal.com


Indeed, last night was cloudy here, too. I'm keeping fingers crossed that tonight will be clearer and I can get out for some observing. If it is really nice, I may drive out into the countryside and get away from the city's light pollution! Last weekend, we had an amazingly clear night on our drive back from Wales. Hopefully we get another one of those this weekend, too! Fingers crossed!!

Meanwhile, good luck with clear skies over the Windy City! If you would like, you and [livejournal.com profile] gyades are welcome to use one (or both) of the two telescopes that I have in the Event Horizon's garage. There is a four inch AstroScan and an eight inch Dob, with eyepieces and filters. You are both welcome to use them, if you like!
Edited Date: 2011-09-10 08:32 am (UTC)

From: [identity profile] acelightning.livejournal.com


Alas, I don't have any binoculars, let alone a telescope. I have to rely on the internet for views of this "nearby" supernova.

(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.)

From: [identity profile] xirpha.livejournal.com


When I was ten, I got a reflector kit for christmas. My dad hope that we would take the class at the Adler Planetarium to grind the telescope mirror, but that became impracticable when we moved out to the suburb.

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.


From: [identity profile] acelightning.livejournal.com


I can't imagine that there's any way to get the reflector front-surface-silvered, at least not affordably. (And you seem to be only about ten years younger than I am.)

From: [identity profile] xirpha.livejournal.com


The silver coating material cost is insignifant even at todays high prices.

From: [identity profile] acelightning.livejournal.com


It's the processing that gets expensive. Depositing a perfectly even layer of metallic silver on the inside of a paraboloid takes more than kitchen chemistry.

From: [identity profile] xirpha.livejournal.com


I never made the telescope not because of the cost or the time, but I never found the need. Astronomy was advancing so much during the past forty years that I realize very early that a little six inch telescope offer very little chance for real science. Instead I keep up the advances in Astronomy by reading journals and watching TV. Now with the internet it is much easier to keep up with the flood of Astronomy information.

I keep the mirror kit as a reminder that because of my dad encouragement that I have my love of science and engineering.

From: [identity profile] acelightning.livejournal.com


Fifty to sixty years ago, simple observational astronomy ("Hey, is that bright 'star' near the horizon Jupiter or Venus? There's the Big Dipper, so that way must be North!") was the gateway to Science for any intellectually curious child. Now, of course, it's computers, which can bring information about astronomy or any other branch of science (including computer science itself) to that curious child with just a few clicks.
.

Profile

anarchist_nomad: (Default)
anarchist_nomad

Most Popular Tags

Powered by Dreamwidth Studios

Style Credit

Expand Cut Tags

No cut tags