Upcoming Visible Nova in Corona Borealis

[cubinator]

A white dwarf in a binary system in the constellation Corona Borealis is due to blow its top sometime in the next few months. It will reach magnitude +2. I've been checking it nightly when the clouds allow. Tonight is just a little too cloudy for me to see, so if anyone is able to report I'd appreciate it.  Otherwise, I'll assume it hasn't happened yet and won't worry about it.

Keep an eye on this constellation!

https://en.wikipedia.org/wiki/T_Coronae_Borealis

Here's the position of the star, in the red circle:

[SunlitZelkova]

I wish I could help out but it’s all clouds and rain here for the next week 

[cubinator]

9 hours ago, SunlitZelkova said:

I wish I could help out but it’s all clouds and rain here for the next week 

Don't worry, there's most likely plenty of time!

[Nuke]

i was a lot more excited about this than the eclipse. but i havent had a good look at the sky in weeks. so im not exactly sure how to find it. i guess just look for the giant dot in the sky.

[cubinator]

16 minutes ago, Nuke said:

i was a lot more excited about this than the eclipse. but i havent had a good look at the sky in weeks. so im not exactly sure how to find it. i guess just look for the giant dot in the sky.

It's near Arcturus.

[Piscator]

It's also not exactly expected to be giant. More like something of the magnitude of Polaris. Which is a lot, considering it's usually about magnitude 10, but not quite enough to put the sunglasses on.

[cubinator]

11 minutes ago, Piscator said:

not giant

It's the biggest explosion you're ever going to see in your life. Possibly more mass than the Earth undergoing thermonuclear combustion, surpassing a temperature of 100 million degrees, visible in city lights from 3000 lightyears away. It's literally like a planet exploding.

https://academic.oup.com/mnras/article/269/2/323/992661

[Piscator]

Well, no "giant dot in the sky" then if you prefer to be needlessly specific. The point I was trying to make is that, while the event is certainly rare, cool and something to watch out for, it's still something you might very well overlook if you wouldn't know it was there.

[Entropian]

I did some photometry on it in H-alpha, OIII, and SII a while back.  I'm not sure if I still have the data, so I'll pick up some more when it's clear here so that once it goes nova I can get a nice rise and plateau light curve.  Hopefully the weather here will be good when it does actually outburst.

[K^2]

On 4/24/2024 at 8:53 PM, cubinator said:

A white dwarf in a binary system in the constellation Corona Borealis is due to blow its top sometime in the next few months.

Well, it won't blow up. Accumulation of hydrogen it stripped off its binary companion will blow up on the surface, leaving the rest of the white dwarf intact to collect more hydrogen over the next 80 or so years. This might sound like I'm nitpicking, but the reason for it is that it might actually explode. Like, the whole star.

Every time a white dwarf goes through a nova cycle, it gets a little heavier, and that will eventually lead to a core collapse and a Type Ia supernova. The T CrB is currently at 1.37±0.13M_☉, which might be really close to the Chandrasekhar limit of ~1.4M_☉. If the scales are tipped this time, we might get a much bigger light show than anyone's expecting. It's pretty unlikely on the net, of course, as the mass grows over a very long time, but it has to happen eventually.

If it does happen, we'll be looking at a nearly -10 magnitude instead of a +2, which is almost as bright as a full moon, except coming from a single point instead of being spread over a disk, meaning you're not going to miss that in the sky, and you'll probably see it even through a moderate cloud cover. Plus, it will be that absurdly bright for a few days, and will leave a visible remnant for a good amount of time longer.

Again, I have to reiterate, it's pretty unlikely that it will be this time. In fact, seeing a random, unexpected supernova might be more likely. But a +2 nova that you can fairly reliably count on this year is still about as bright as the North Star, which is still cool.

 

So I strongly recommend to anyone who's interested to go and look at the Corona Borealis next time you have decent weather, because it's not that exciting to look at a +2 star unless you've looked at that patch of the sky before and know that this star wasn't there. And maybe get into a habit of looking at it every time. Sure, it'll be on the news when it happens, but it's so much more fun if you get to discover it for yourself. Just looking up at the sky and seeing a star that wasn't there yesterday.

[Elthy]

How long is the nova gonna last?

[cubinator]

10 hours ago, K^2 said:

Every time a white dwarf goes through a nova cycle, it gets a little heavier, and that will eventually lead to a core collapse and a Type Ia supernova. The T CrB is currently at 1.37±0.13M_☉, which might be really close to the Chandrasekhar limit of ~1.4M_☉. If the scales are tipped this time, we might get a much bigger light show than anyone's expecting. It's pretty unlikely on the net, of course, as the mass grows over a very long time, but it has to happen eventually.

If it does happen, we'll be looking at a nearly -10 magnitude instead of a +2, which is almost as bright as a full moon, except coming from a single point instead of being spread over a disk, meaning you're not going to miss that in the sky, and you'll probably see it even through a moderate cloud cover. Plus, it will be that absurdly bright for a few days, and will leave a visible remnant for a good amount of time longer.

Again, I have to reiterate, it's pretty unlikely that it will be this time. In fact, seeing a random, unexpected supernova might be more likely. But a +2 nova that you can fairly reliably count on this year is still about as bright as the North Star, which is still cool.

That's very interesting! Since it's always gradually accumulating mass, would we really expect the supernova to occur at the same time we expect the periodic nova, where the nova is the thing that 'stomps' it into a Type Ia? Or would it just get up to the limit at some point during accretion? I'm going to do some more reading on this.

If it did supernova, I suppose that would trigger a neutrino burst that would register in the Supernova Early Warning System?

[Entropian]

2 hours ago, cubinator said:

If it did supernova, I suppose that would trigger a neutrino burst that would register in the Supernova Early Warning System?

It's only around 800 parsecs away; if SNEWS ever actually triggers for once, then it'll be in a case like this.

[magnemoe]

5 hours ago, cubinator said:

That's very interesting! Since it's always gradually accumulating mass, would we really expect the supernova to occur at the same time we expect the periodic nova, where the nova is the thing that 'stomps' it into a Type Ia? Or would it just get up to the limit at some point during accretion? I'm going to do some more reading on this.

If it did supernova, I suppose that would trigger a neutrino burst that would register in the Supernova Early Warning System?

I guess the nova create an downward pressure who might trigger the supernova slightly before 1.4 , after the nova mass would go down some before starting building up, no idea above the downward force strength and if an nova going super is probable. 

[K^2]

9 hours ago, cubinator said:

Since it's always gradually accumulating mass, would we really expect the supernova to occur at the same time we expect the periodic nova, where the nova is the thing that 'stomps' it into a Type Ia? Or would it just get up to the limit at some point during accretion?

I believe it's a nova cascading into a supernova, because there would be a compression to the core as the nova's shockwave travels inwards, but it also might depend on things like rate of accretion and the angular momentum of the white dwarf. The information on this is a bit sparse, and it might be that we don't have a particularly good model. I'm almost confident in saying we don't have good data on it either way. It's something I'd run past an astrophysicist, though, if you want to be certain.

9 hours ago, cubinator said:

If it did supernova, I suppose that would trigger a neutrino burst that would register in the Supernova Early Warning System?

It should. What I actually don't know is whether a regularly scheduled nova we're due is expected to be visible on any of our neutrino detectors or any of our gravitational observatories. I do know that everybody in the astrophysics community is getting ready to capture data relevant to their field of study, though, so I'm sure we'll find out after the fact all the spectacular ways in which we were able to observe it directly or indirectly. And there are enough people watching the star through conventional telescopes, both in professional and amateur communities, to make sure we aren't going to miss it.

[cubinator]

39 minutes ago, K^2 said:

believe it's a nova cascading into a supernova, because there would be a compression to the core as the nova's shockwave travels inwards, but it also might depend on things like rate of accretion and the angular momentum of the white dwarf. The information on this is a bit sparse, and it might be that we don't have a particularly good model. I'm almost confident in saying we don't have good data on it either way. It's something I'd run past an astrophysicist, though, if you want to be certain.

I wanted to find out how long the combustion lasts, to figure out what that additional pressure might be and calculate the mass 'margin' that it would have to be within to trigger, but the closest I could find to a specific description of the 'action' was a written account from a past eruption saying the magnitude increased by >1 per hour, which doesn't help me much.

[Entropian]

1 hour ago, cubinator said:

I wanted to find out how long the combustion lasts, to figure out what that additional pressure might be and calculate the mass 'margin' that it would have to be within to trigger, but the closest I could find to a specific description of the 'action' was a written account from a past eruption saying the magnitude increased by >1 per hour, which doesn't help me much.

Early observation, photometry, and spectroscopy of supernovae is very much a growing field and has only recently become more common.  I'm sure a lot of people would really appreciate more detailed photometry of eruptions like that, but ultimately the systems for automatic detection and response have only come up in recent years.  To somewhat back up my words, I actually work in research on data collection and analysis of young supernovae.

Edited April 29 by Entropian
mi gramahr badd

[K^2]

2 hours ago, cubinator said:

I wanted to find out how long the combustion lasts, to figure out what that additional pressure might be and calculate the mass 'margin' that it would have to be within to trigger, but the closest I could find to a specific description of the 'action' was a written account from a past eruption saying the magnitude increased by >1 per hour, which doesn't help me much.

Hand-wavy argument. Luminosity decays within days and spikes sharply. So we aren't talking about a process that slowly ramps up and turns the accumulated hydrogen into a slowly expanding atmosphere. We're talking an explosion - critical mass and temperature are reached, hydrogen ignites, and the released energy launches the ejecta on a ballistic trajectory. Which means the peak pressure has to greatly exceed the weight-pressure of the accumulated material, as the duration over which the pressure is applied is much, much shorter than the ballistic phase, and the total impulse has to match.

[magnemoe]

11 hours ago, K^2 said:

Hand-wavy argument. Luminosity decays within days and spikes sharply. So we aren't talking about a process that slowly ramps up and turns the accumulated hydrogen into a slowly expanding atmosphere. We're talking an explosion - critical mass and temperature are reached, hydrogen ignites, and the released energy launches the ejecta on a ballistic trajectory. Which means the peak pressure has to greatly exceed the weight-pressure of the accumulated material, as the duration over which the pressure is applied is much, much shorter than the ballistic phase, and the total impulse has to match.

Kind of like the chemical explosives set off an nuclear bomb who then set off an thermonuclear one. On issue is that white dwarfs are a bit heavier than nuclear bombs so you have an significant inertia. 
But an nova followed by an supernova would be cool. 

[JoeSchmuckatelli]

On 4/28/2024 at 12:47 AM, K^2 said:

we'll be looking at a nearly -10 magnitude instead of a +2, which is almost as bright as a full moon, except coming from a single point instead of being spread over a disk, meaning you're not going to miss that in the sky, and you'll probably see it even through a moderate cloud cover

...and, well great, it's an election year - so someone will spin this into a signal from the illuminati. 

Meaning I will have to explain to my students that no it's not aliens just science. 

[K^2]

11 minutes ago, JoeSchmuckatelli said:

Meaning I will have to explain to my students that no it's not aliens just science. 

- "Executor, you have summoned me?"
- "Yes, Admiral. I have need of your expeditionary force. You will depart with it at once. We just received a word from the long range xeno-prognosis department that there will be an election on Earth, in the Sol system, in a few hundred years.*"
- "Sol?"
- "A backwater system in the Orion Arm. It is far away from any trading routes and has a lone habitable planet with a pre-expansion civilization."
- "And that election..."
- "Of the utmost importance."
- "I see. Are they on the verge of electing a leader of their planet that's destined to take them to their interstellar glory?"
- "No. Just a chieftain of one of their tribes for the next four years."
- "..."
- "They will be picking between two elderly specimens, either of which might not even live long enough to finish the term."
- "Executor..."
- "The analysts at xeno-prognosis assure me that this is crucial and we must ensure a specific outcome."
- "So we're going to... Earth? To deliver the message? Shall we broadcast it after revealing our fleet? Or send undercover agents to infiltrate their governments and media, perhaps?"
- "No. See this binary 800 parsecs away? It is on the verge of going supernova. I need you to adjust its orbit to time the supernova with the election, sending a clear signal to the inhabitants of Earth."
- "... You're just trying to get back at me for that comment I made at your party."
- "I would never! Anyways, the paperwork is already signed. Have a great journey, and I hope you won't have to suffer anything as horrible as stale hors d'oeuvre on your voyage."

 

* Editor's note: Names and units translated for reader's convenience.

[JoeSchmuckatelli]

11 hours ago, K^2 said:

"..." 

I am so going to use this! 

[K^2]

32 minutes ago, JoeSchmuckatelli said:

I am so going to use this! 

You may cite me as Katherine the Illustrious.

[JoeSchmuckatelli]

6 hours ago, K^2 said:

You may cite me as Katherine the Illustrious.

Done! 

[cubinator]

I took a few images a couple hours ago and I think it looked a little brighter than expected. Like somewhere between magnitude 9.35 and 10? Could easily still be in the 10 range though based on the variation in my data.

Edited May 27 by cubinator