234 replies to this topic

[Dave Mitsky]

I imaged T CrB again last night with my Seestar S50. It didn’t seem to be much different than in my previous images.

[Dave Mitsky]

Here's my Seestar S50 image from Saturday night.  I was at the Big Dipper Lodge, which is half a mile from Cherry Springs State Park.  The conditions were not very good that night.

Attached Thumbnails

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[brooklynlou]

Doesn’t look all that different. I’m on vacation now so my assumption is that it will blow up any minute now 🤣

[Ionian]

Anything new?

[thedude_01]

Still a big blank spot in the sky 

[Bob_Gardner]

You can follow the variations in brightness in near real time on AAVSO at https://www.aavso.org/LCGv2/

 

 

IIRC, the solid green squares are based on visual band images, the open black circles are estimates made by visual observers with binoculars or telescopes, and the black upside down triangles are the upper limit on possible brightness made by visual observers.  The other colored symbols represent magnitude estimates made using images taken through various filters.  

 

https://www.aavso.org/filters

Edited by Bob_Gardner, 18 September 2024 - 12:28 PM.

[truckasaurus]

I was looking at sky safari and it looks like in my area (SoCal) mid to late October will be it for early evening observing.  two weeks after that it'll have to be in the mornings from mid November on.   It'll be back in the early evenings in early May.....watch it happen in the first couple of weeks of November when it will be very hard to observe......  

Edited by truckasaurus, 26 September 2024 - 10:38 PM.

[PlanetNamek]

You know what, maybe I'm asking for too much here but how can we not get a more accurate timeline to when we can expect to see this Nova? Why not look at our findings for other stars in the same class/spectrum and see approximately how long it took them to go Nova. Of course, you can't have a perfect prediction but that could be a start. I think this whole thing has kinda been put on the back burner.

[Redbetter]

You know what, maybe I'm asking for too much here but how can we not get a more accurate timeline to when we can expect to see this Nova? Why not look at our findings for other stars in the same class/spectrum and see approximately how long it took them to go Nova. Of course, you can't have a perfect prediction but that could be a start. I think this whole thing has kinda been put on the back burner.

Schaefer et al didn't update their estimate early after their prediction, even after the dip they were touting failed to materialize.  Since the dip didn't actually happen, their assumption about a timeline based on it was bogus to begin with.

 

All we have to go off of is the the previous cycle length and some observations of what is believed to have been a previous cycle.  Quoting myself from a month ago:

 

The most recent period was ~79.75 years.  There was supposedly an outburst in late 1787 (not well documented), with that period being around 78.4 years.

 

If the most recent period is close to the average, then the event would be most likely occur centered on a date of 11/08/2025, but that wouldn't put a cap on how much later it could be.   

 

If instead, the average of the two most recent periods is used then the center point of the estimate would be ~ 3/15/25, but again this doesn't put a cap on how late it could be. 

 

It could happen tonight, it could happen years from now.

 

I will add in that if we do see a deep dip as they thought we were seeing last year, then things get interesting.  If that happens will it follow their estimated timeline (with the actual dip date) or will it differ substantially from how they think the prior one played out?

[yuzameh]

You know what, maybe I'm asking for too much here but how can we not get a more accurate timeline to when we can expect to see this Nova? Why not look at our findings for other stars in the same class/spectrum and see approximately how long it took them to go Nova. Of course, you can't have a perfect prediction but that could be a start. I think this whole thing has kinda been put on the back burner.

impossible to predict novae, never been done, never can be done, it's been hypothesised that novae repeat, as they were hyper-extreme WZ Sagittae type pairs, but it has never been seen so there is no proof and although some cataclysmic variables appear to have evidence of nebulosity with several shell borders I'm not aware of any novae known with any (well, maybe GK Persei, however that nova of a century and a bit ago became a dwarf nova, which do repeat regularly enough, mostly, oh, and totally unpredictably.

 

Anyway, T CrB isn't a nova.

 

It is called a Recurrent Nova.  Novae were discovered first and other types of white dwarf with a mass donor star companion tend to be "something" novae even when all they have in common is a white dwarf and mass donor star.

 

Recurrent Novae are actually a mixed bag, that is are they 'polyphyletic'.  If we ignore the LMC recurrent novae mostly becasue LMC novae and MW novae are quite different in metallicity (former very metal poor) which leads to all sorts of differences, we have only four known classic Recurrent Novae.  More are listed, up to ten, but some haven't all that much data and could well be other types - one or two have been called something else in their most modern repeat.

 

The four classic RNe are U Sco, T Pyx, RS Oph and T CrB.  You can't compare that group.  U Sco and T Pyx have main sequence donor stars (might be called RNB, can't remember) however they aren't alike either it seems.

 

RS Oph and T CrB have red giant donors and were called RNA, the A simply means they are fast and fade quickly after outburst, it is more or less a copy of a similar scheme used, or once used possibly, for Novae, which were NA, NB and NC depending on their fade rate.

 

RS Ophiuchi goes off ever dozen to twenty years, with long gaps when it was either missed (possibly nobody cared to look in those days) and/or was too close to the Sun and being a fast fader readily missed.

 

These two are extreme versions of Symbiotic Stars, which can have Semiregular or Mira stars and occasionally outburst brightenings on top of those but of far lower amplitude compared to true RNe.  There is a gradiation between those two types called SyNe, that's Symbiotic Novae, and these have a magnitude or two outburst every now and again, not always known to repeat as the timescale between repeats is likely too long for us to see them doing it more than once, and like slow novae can take a long, long time to gently and slowly fade (up to years and years in some cases).  Their timescales are all over the shop.  One symbiotic star which could as readily be called a symbiotic nova is R Aquarii which has nebulosity surrounding it (Cederblad 211) which may have been due to a novae type outburst over a thousand years ago, so that would have a very long time scale.

 

Or in other words, no, you can't predict it, anyone who says they can is conning themselves, and there is NO dip just prior to the last outburst, just Leslie Peltier noticing the orbital ellipsoidal variation for half a cycle for the first time, with no other observer logged as observing it at that time according to the AAVSO database use by BS (apt initials), so no independent confirmation.

 

You can add up the time gap between the 1866 maximum and the 1946 maximum and add that to the 1946 maximum and you get early November 2025.  Doesn't necessarily mean anything but it does give a time scale.  However, given the percentage variation in outburst times in RS Oph it might not blow up until century has passed, ie mid 2040s.  Or if some of the gaps when RS Oph should have gone into outburst are real gaps as opposed to Sun interference or missed chances then it ain't gonna need to go boom anyway.

 

Short answer : it's impossible.

[stanislas-jean]

The question is that the model that prevails until this year is not functionning properly.

This is not a reason for stopping a survey.

Good skies.

Stanislas-Jean

[RLK1]

I see the pros aren't giving up on it:

 

"However, as both Cooke and Wilson noted, the window in which T CrB could appear is wider — by months, even. If it doesn’t explode soon, we may even miss it."

“Hopefully it will explode this month. If it doesn’t, it’ll actually be very inconvenient because it’s about to go behind the sun,” Wilson told Nexstar, explaining that we wouldn’t be able to see the explosion then. It won’t be back in our night sky until early next year."

 

"Should T CrB reach nova status before it goes behind the sun, or once the Northern Crown returns to our night sky, we’ll only get to see the new star for a few days.

According to Wilson, it will take the star about a night to go from “its current brightness to its peak brightness.” Then it will dim and disappear — a process that could last a few days to a week."

 

“It’s not going to get that bright,” he explained, comparing it to the North Star. It will, however, be bright enough that many of our space telescopes will not be able to see it for the first few days, Wilson said. “For the first few days, it will mainly be the smaller, amateur telescopes that will be doing most of the work.”

 

"For now, Wilson said T CrB is being “constantly tracked” by amateur astronomers around the world."

 

https://thehill.com/...th-where-is-it/

 

Ya all continue your fixation, ya hear?....

[azure1961p]

As Don has indicated, T CrB is simply a recurrent nova, there is no such thing as a recurrent supernova. At the same time, I followed T CrB visually for some 60 years and never saw it fainter than the late 10's in magnitude, so the current brightness of 10.5 is typical of the star being at minmum phase.

 

BrooksObs

Can you imagine a recurrent SN?  Blows it's self to smithereens, regroups, blows again, each time a new black hole lol.

[gfamily]

Can you imagine a recurrent SN?  Blows it's self to smithereens, regroups, blows again, each time a new black hole lol.

Arguably that's what has happened (to some extent) with every Population I star - albeit that the metal rich remnants of the supernova gets mixed in with a healthy proportion of primordial H and He 

[Kid_A]

Are we giving up on this thing, or what? Was the interpretation of the data incorrect or incomplete? What gives?

[Dave Mitsky]

T CrB NOVA WATCH
today: m=10.2 (Oct 12.8)
yesterday: m=10.1
more: AAVSO data

 

https://www.spacewea...th=10&year=2024

[Keith Rivich]

Are we giving up on this thing, or what? Was the interpretation of the data incorrect or incomplete? What gives?

Welcome to the world of error bars!

[yuzameh]

Are we giving up on this thing, or what? Was the interpretation of the data incorrect or incomplete? What gives?

That's up to you.

 

T CrB should blow up sometime between 2020 and 2030, although that's not entirely guaranteed even then.

 

Just because some bloke how happens to be a professor wrote a load of drivel and all the science news sites took it all in hook line and sinker, as did nasa, and quoted the drivel nearly verbatim (I say nearly, as some of the professional scientists quoted have talked even more drivel, and not been misquoted either, they evidently knew little to nothing about cataclysmic variables and most of them called it a nova when it is not a nova, so don't even understand the taxonomy of eruptive white dwarf companions).

 

At total guess level it was a set time between the two certain outbursts and adding that set time to the last certain outburst gives early November 2025, yet no red giant primary star recurrent nova is known to repeat that regularly, even to the year.

 

Some people have been observing this star since the last outburst.  I know of at least one person, a long time well known variable star observer, who for many years had observed it (I observed it myself for a while in the 90s, as it is variable even at quiescence, ellipsoidally and at time flickeringly, albeit both to low amplitude), yet ironically dropped dead earlier this year despite no sign of significant ill health prior to that.  I feel more sorry for him than for those who are whining because they missed the hype that was all the same continued copying (and like chinese whispers, slow malforming of the original drivel into barely understandable statements) of each other from the original very, very weak paper.

 

Variable star observers watch stars like this repeatedly or with a wide window centred on the rough timescale, yes TIMESCALE, not period.  Solar Maximum has a timescale, often called an 11 year cycle (really a 22 year) as if it was a rigid periodicity.  If you really want to see this outburst you keep looking till late 2026 and watch its behaviour, it's not a performing poodle willing to jump through hoops for the instant gratification of some audience.

 

It'll outburst when it does, or not.  Where at the right timescale now for it to be potentially due but the margin for error is large because of only two firm prior dates (the other two, one suggestive but with no independent confirmation, and the other the height of drivel as the apocryphal record of some monk actually states, as actually quoted in the T CrB outburst paper, that it was visible for weeks, when T CrB has only been naked eye for about a week on last two outbursts, and all recurrent novae have outburst even timescales related to their subcategory.  There weren't that many telescope around in the 1200s anyway...

 

There is no absolute truth in science.  Those wanting absolute truth need to take up a faith or a belief and obey the inherent dogma irrespective of evidence.

[LoudounStargazer22]

T Cor Bor, do something 

[Bob_Gardner]

The case for T CrB doing something can be found here:

https://www.aavso.or...re-eruption-dip

 

I believe the point of the article is:

 

"So the T CrB Pre-eruption Dip has already started in March/April of this year.  If the Dip in 2023 is similar in timing to that in 1945, then the primary eruption should occur roughly 1.1±0.3 years later, or in 2024.4±0.3.  This prediction is substantially improved over the prior predictions based only on the 2015 rise to the high-state.  Still, possible deviations from the behavior in 1946 could create an early or a late eruption."

 

Predicting an exact date isn't really the purpose of this paper.  The reason is described as follows:

 

"This announcement of the start of the Dip and the prediction of the eruption date (2024.4±0.3) will hopefully be of use for researchers for making proposals with a wide variety of telescopes.  Further, this serves as advance notice to take all needed pre-eruption baselines, for example obtaining infrared fluxes and background nebulosity images over a wide field for later light echo detections.  And it is not too late to try to understand the pre-eruption high-state, with it still being unclear whether the increased luminosity comes from increased accretion or from nuclear burning on the white dwarf.  For observations before the upcoming eruption, we particularly point to U-band photometry, UV spectrophotometry, and spectral line profiles, all for measuring the energetic physical mechanism of the Pre-eruption Dip, while long-running infrared photometry might detect dust formation."

 

Dr. Brad Schaefer is cited as the lead author:

https://en.wikipedia...radley_Schaefer

 

I didn't realize until I googled this just now that Dr. Schaefer is the same person who authored a Great Course on Ancient Astronomy that I listened to as an audiobook last year.  It was very interesting and educational and I recommend it highly to anyone interested in the topic.  He's an excellent writer and science communicator.

 

And I just noticed that this course is reduced for close out at a significant savings:

https://www.thegreat...cient-astronomy

Edited by Bob_Gardner, 16 October 2024 - 09:07 PM.

[Redbetter]

The point of the article was completely off, because there was no pre-eruption dip of the magnitude that was believed to have been observed prior to the 1946 eruption.  Instead the dip was much smaller and signaled a return to more typical ellipsoidal brightness variation.  Schaefer blew it by jumping the gun and claiming a dip before it actually happened (the big dip still hasn't happened...although it still could.)   Rather than following the data, he assumed the direction it would go.  The failure was more in that he didn't communicate to anyone that his prediction itself was in error once this became clear.  He continued to hype an event to the media, based on an assumption that was soon shown to be false.  I don't appreciate being misled by someone who should know better. 

 

Schaefer gets some of the basic stuff wrong on a regular basis when it comes to observational astronomy (see his claims with respect to NELM for an example that a layman can easily refute.)  His biases are problematic.  

 

Not that it is bad that folks are closely monitoring the star (pair) at this time, but I wouldn't give much weight to Schaefer's specific predictions.  

Edited by Redbetter, 17 October 2024 - 12:11 PM.

[Tony Flanders]

In my experience Brad Schaefer is brilliant, original, stimulating, and more often than not wrong.

[Bob_Gardner]

In my experience Brad Schaefer is brilliant, original, stimulating, and more often than not wrong.

You sound like you might be a scientist, sir!

 

"Science is the organized skepticism in the reliability of expert opinion." -- Richard Feynman

Edited by Bob_Gardner, 19 October 2024 - 04:20 PM.

[PlanetNamek]

I guess November now?......

[jjbroomco]

Perhaps because today is Halloween, there is a resurgence of this story across various news outlets, with headlines about a “zombie” star that is expected to be visible “within the next few days.” My local news was one of many who reported on it and interviewed a NASA astrophysicist who explained what is happening with T Cor Bor.

Here we go again…