Sometime between May and September, a white dwarf is expected to go thermonuclear.
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If you can see the Big Dipper, you’ll get to see a star go nova soon
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Neat! It's really been a gangbuster year for amateur astronomy (or just the astro-curious) in the US. Hope it's not a portent of anything, but there's been a lot that you can go out and see with the naked eye, more than I ever remember in years past.
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White dwarves are still considered stars, just post-main-sequence, and they emit energy as black body radation due to their extreme residual heat. There's also T Tauri stars, which are pre-sequence and the energy they emit is from gravitational collapse, as they're not dense enough yet to initiate fusion.
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By definition, the term is "thermonuclear fusion." However, white dwarves are past their fusion period, so, no, not all stars are always going thermonuclear.
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All stars are black body radiators. Well, at least our active Sun is.
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According to the article the star is a white dwarf so normally it doesn't fuse hydrogen since it ran out eons ago. It's just this one has a doner star that slowly re-fuels it enough for a couple of days of fusion every 80 years or so.
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Even for the ones that are actively fusing, is it correct to call it thermonuclear? As I understand the fusion happens not from heat but actually quantum tunneling due to the extreme gravity.
Or is that only for some kinds of stars? Do others fuse because of heat or is it always quantum tunneling? Or am I interpreting "thermonuclear" too literally?
Starstuff beings that know more about star stuff than me, how's this all work?
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No. White dwarfs, as the article notes, do not. They are “merely“ the incredibly hot leftovers of red giants that have run out of hydrogen.
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Normal stars burn fuel continuously and regulated in a stable way, like a fusion reactor. While this is a hydrogen fusion explosion aka thermonuclear bomb, which is what they meant with thermonuclear.
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you don't really need it for this, it should be naked eye visible. Its not much to look at though, there will simply be a seemingly normal, additional star visible in the Northern Crown that wasn't there before.
I think to experience it to any extent, you should just find and get some memory of the Northern Crown's appearance now, before it appears, so that you can get that "oh, look this wasn't there before" impression when it happens.
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TacticalGeek
Wise, Aged Ars Veteran
I hope we have clear skies when it happens. I'd love to check it out through my telescope.
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It should be visible for a few days if you just have your eyes, longer if you have some binoculars. So hopefully plenty of time to see it.
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Thanks! Does that include looking with a pair of binoculars? And how long will the "extra" star be there.. do we have a day or two to get our butts to a good observation point once it goes nova?
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Why does it get dimmer before it explodes? It can't be due to a build-up of hydrogen cooling it or blocking the light, since that occurs over 80 years.
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the time aspects of astronomic events always intrigues and amazes me.
T. Coronae Borealis is ~2600 light years away, so the event happened long before we switch to AD calendars and we are simply waiting for the light evidence to arrive. And by the time it arrives, ~32 nova events will have already happened, we are just waiting for the results to come in.
My mind struggles with these enormities of scale.
T. Coronae Borealis is ~2600 light years away, so the event happened long before we switch to AD calendars and we are simply waiting for the light evidence to arrive. And by the time it arrives, ~32 nova events will have already happened, we are just waiting for the results to come in.
My mind struggles with these enormities of scale.
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Okay so my homework for now is locate Coronae Borealis between Vega and Arcturus, then familiarize myself with the absence of T Coronae Borealis when viewed through binoculars.
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To the more knowledgeable astronomers here.. am I right that this will be a type Ia supernova, so we have a chance to observe a type of standard candle with our own eyes?
(edit - answered below - unfortunately no)
(edit - answered below - unfortunately no)
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Ten points for crossing an Animal House reference with astrophysics.
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Thanks for the reminder. I had forgotten about this. I need to clean, check and realign my telescope's main mirror asap. Maybe needs a replacement if the coating is starting to grenade,
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No it won't be. This is only a nova, nothing super about it. This means the white dwarf will survive the explosion while a 1a supernovae would disrupt the entire star.
A 1a supernovae would require you to ignite the carbon deep inside the white dwarf and have that start burning explosively. This nova will only burn the outer layers of hydrogen without igniting the carbon at the center.
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This is an interesting factoid. Thanks for sharing!
Does anyone know if there is a service similar to SpotTheStation that would send a text or email when professionals/scientists notice when the event happens so I can know to go out and look? I guess, at the very least, Ars will post a new article?
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Ah, I see the article also mentions this though I didn't pick up on it:
"The explosion is a nova, which means it doesn’t kill either the white dwarf or the red giant as a supernova would. “Only about 5 percent of the hydrogen layer fuses into heavier elements like helium, and the rest just gets ejected into space. Then the process starts all over again because the explosion isn’t large enough to disrupt the red giant, the donor of all this hydrogen, so it just keeps doing its thing,” Van Belle told Ars. This is why we can predict this event with such precision."
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I think they mean conceptually, not comparing to a reactor that actually exists today.
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There are reasons to suspect Betelgeuse is on the younger side, so you may need to wait longer. I suggest packing dinner as well.
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Yep It's Me
Ars Centurion
In the Daily Telescope articles, @EllPeaTea is renowned for providing little maps. But I think they're in Europe and in the evening hours now, so might not have seen the article.
Here's the raw map that EllPeaTea would base theirs off:
https://en.wikipedia.org/wiki/File:Corona_Borealis_IAU.svg
And here's a good article from Astronomy.com that provides several good maps. The map with T CrB specifically pinpointed is at the bottom. It's rather hard to see the green dot they placed, Follow the line of the last 3 stars in the constellation as a pointer.
https://www.astronomy.com/observing...orealis-the-brightest-nova-of-the-generation/
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"Any day now" made me think it would happen in the next few days. I need to reset my time scale to cosmological instead of human. Because I am human and not an robot AI. Believe me.
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There are interesting questions about whether novae phases of a white dwarf life is needed as a step towards a 1a supernovae. To make a 1a supernovae you need to push a white dwarf above 1.4 times the mass of the Sun. You could do that either by acceating material from a companion, like this system, but then you have novae explosions, like this system, blowing most/all that accreted material off the white dwarf so it might grow in mass very slowly. The other way is to start with two white dwarfs and smash them together, but then you have issues with how many double white dwarf systems we expect to merge. There's a enough diversity in 1a explosions that's it's probable we need abit of both types, plus maybe other more unusual mechanisms for certain sub types of 1a supernovae.
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T. Coronae Borealis is at about declination 26 degrees north (26 degrees north of the celestial equator). So, not counting a bit of refraction at the horizon, it would just clear the northern horizon from 64 degrees south latitude at it's highest, with a degree higher for every degree further north in latitude. So should be visible from most of the Southern Hemisphere. I know I can clearly see objects at declination 26 degrees south from my location at 30 degrees north latitude.
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danielravennest
Ars Tribunus Angusticlavius
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