- This topic has 79 replies, 19 voices, and was last updated 2 weeks, 4 days ago by
.
-
Posts
-
Light curve from tonight.
Attachments:
Hi Maxim,
I monitored it in R, V and B last night for over 2 hours and I found it was quite flat with only the B being slightly variable (as usual). See attached graph of last night’s results and also one with all my data since April.
Cheers
Ian.Attachments:
Might be of interest. The Times, May 21st 1866 and February 13th 1946.
Hoping for more coverage than 1946 in 2024, or 2025 or 2026?
Attachments:
Steve,
You’ll probably find Jeremy Shears article in VSS Circular 200 of interest, as it contains this snippet from the Times and a whole lot more…
https://britastro.org/vss/VSSC200.pdf#page=8
Gary
Gary,
Thanks for that. Most interesting.
It was Jeremy’s talk in June 2023 that sparked me delving into The Times archive. I wanted to see if there was any sign of John Birmingham’s lost discovery letter.Alas no.
Steve
Last night I made an observation of T CrB before the fog came in. The star HD143256 in SkySafari was used for comparison and was the same magnitude as T CrB.
2024/8/5 4:34 U.T. Estimated visual magnitude 9.8. 15″ Newtonian at 92x.
Dean
Invitation to Brad Schaefer’s Zoom talk on August 17th regarding the predicted eruption of T CrB
I am sharing this invitation from Edwin Aguirre about this Zoom talk on August 17 (Saturday) at 1:30 p.m. UTC (14.30 BST)
It will be interesting to hear his prediction for the time of the eruption.Jeremy
I would like to invite you and the BAA members to Brad Schaefer’s Zoom talk on August 17 (Saturday) at 9:30 a.m. EDT (1:30 p.m. UTC) regarding the anticipated eruption of T Coronae Borealis. The talk is free and open to the public.
Attached are the details of Brad’s online talk. In addition to Zoom, the event will be streamed on Facebook Live and recorded for YouTube viewers.
NOTE: Everyone needs to register first in order to get the Zoom link for the webinar. You can either scan the QR code on the attached announcement with your cellphone or go directly to the Zoom registration page:
https://us02web.zoom.us/webinar/register/WN_Bm_NLfhkSQyG0Es31OYkqg#/registration
Brad’s talk is part of the “Astronomy Experts Speaker Series” that Imelda and I started two years ago in collaboration with the Astronomical League of the Philippines. As you know, the Philippines is a relatively small developing country in Southeast Asia, and many people there cannot afford to travel overseas to attend astronomy seminars and conferences.
So, our goal is to help raise public science literacy and awareness in the country by inviting renowned scientists, researchers and science communicators to share their knowledge and expertise online with the Filipino people through our Zoom webinar series. It is all part of our international astronomy educational outreach efforts.
To date, our guest speakers have included:
Prof. Jay Pasachoff (Williams College), who talked about his 2021 Antarctic solar eclipse expedition
Zolt Levay (STScI), who discussed the Hubble Space Telescope’s most iconic images
Dave Eicher (Astronomy magazine editor-in-chief), who spoke about galaxies and galaxy classification
Fred Espenak (Mr. Eclipse), who talked about predicting and chasing total solar eclipses
J. Kelly Beatty (Sky & Telescope magazine senior editor), who spoke about the fight against light pollution
David Levy on how he and the Shoemakers discovered Comet Shoemaker-Levy 9
Heidi Hammel (AURA vice president for science), who spoke about the James Webb Space Telescope’s latest findings
Dan Green (CBAT director), who discussed the nature of comets
Debbie Elmegreen (IAU president), who talked about galaxies at the dawn of the Universe
Father Chris Corbally, S.J. (Vatican Observatory/Steward Observatory), who explained the mystery of “The Star of Bethlehem”
Brother Robert Macke, S.J. (Curator of the Vatican Observatory’s meteorite collection at Castel Gandolfo, Italy), who talked about meteorites, asteroid 101955 Bennu, and the OSIRIS-REx mission
Brother Guy Consolmagno, S.J. (Vatican Observatory director), who talked about Vesta and the Dawn mission
Valentin M. Pillet (National Solar Observatory director), who discussed the solar corona and the current Solar Cycle 25
Mike Brown (Caltech), who talked about Pluto and the search for Planet Nine
Robert Nemiroff (Michigan Tech), co-founder and editor of NASA’s Astronomy Picture of the Day (APOD)
Jonathan McDowell (Harvard-Smithsonian Center for Astrophysics), who spoke about the Chandra X-ray Observatory and the invisible Universe.
For fall/winter, we plan to have Meg Urry (Yale University), who will talk about the supermassive black hole lurking at the center of the Milky Way, and Michael S. Kelley, program scientist for the Planetary Defense Coordination Office at NASA Headquarters, who will discuss the impact threat posed by NEOs, and for next year, NASA astronaut Don Pettit, who will talk about astrophotography from the International Space Station. We are currently finalizing the schedules for their respective webinars.We hope you can join us for Brad’s talk on the 17th!
Best regards,
Edwin
Attachments:
Just watched an excellent presentation on TCorBor by Brad Schaefer, a webinar for the Astronomical League of the Philippines. Should be on their YouTube channel before long if anyone would like to see it.
AlanNo real updates on Brad’s prediction of the eruption during his webinar. His best prediction is based on fitting the light curve from ~2015 to now with the light curve leading up to the 1946 eruption which gives 2024.4 +/- 0.3. He reckons we are at, or near, the bottom of the pre-eruption dip. He was saying the eruption could therefore be any day now, as we are still in his predicted Feb to Sep window. It could also be in the next weeks or months, but likely before the end of the year.
Brad also discussed his analysis of the intervals between the 4 known eruptions (1946, 1866, 1787, 1217), which leads to ~2024.7 for the next one, i.e. ~ September.
I’ve updated the website article on observing T CrB with the latest info: https://britastro.org/section_news_item/get-set-for-the-next-eruption-of-the-recurrent-nova-t-coronae-borealis
I’ve mentioned the independent discovery of the 1946 eruption of T CrB by 15-year old Michael Woodman in recent VSS Circulars.
I’ve recently had the privilege of meeting him and have subsequently written this note in RNAAS, highlighting how his observation helps to fill in our understanding of the early stage of the eruption:
https://iopscience.iop.org/article/10.3847/2515-5172/ad7ba8
I very much hope he will have the opportunity of seeing the next eruption, whenever that might occur.
Go well!
JeremyJeremy. In reviewing the 4 definitely observed eruptions, Brad Schaefer’s comments that the recurrence timescales are 7×81.4, 78.5, 79.7, and then states a likely 78.3 ± 0.3 yr should apply between 1946 and the next eruption. So that translates to 2024.4 ± 0.3. I don’t understand how he can ascribe such a small uncertainty (± 0.3 yr) in this prediction. Statistically from the above numbers you could envisage a distribution in which 9 eruptions span the range 77 to 85 yr, and that since the last two have been in the lower half of that distribution, the next event has more chance of being in the higher half, i.e. more like 82 ± 3 yr, which then takes it to the beginning of 2026. It does look like he has made an assumption that the periodicity is for some reason decreasing on average monotonically in a somewhat linear fashion. Is there some theoretical reason why that might be the case, I wonder?
P.S. Brad Schaefer has done all sorts of research over the years. Am putting together a paper at present that uses three references to his work from 1985, 1986 and 1987. He writes that he was the first to work on this subject since antiquity and few if any other visual observers have since investigated this topic. The references are:
Schaefer, B.E., 1985. “Predicting heliacal risings and settings”, Sky and Telescope, lxx, 261–3.
Schaefer B. E., 1986, “Atmospheric extinction effects on stellar alignments”, Archaeoastronomy (Supplement to Journal for the History of Astronomy), (10), S32–42.
Schaefer, B.E., 1987. Heliacal rise phenomena. J. Hist. Astron., 18(11), S19.Richard, the 2024.4 (+/- 0.3) estimate does not come from Brad’s analysis of the intervals from these earlier eruptions, but from a comparison of the light curve over the last ~10 years with that leading up to the 1946 eruption. They show common features, like a “super active state”, pre-eruption dip. This is described here:
https://ui.adsabs.harvard.edu/abs/2023MNRAS.524.3146S/abstract
And refined here:
B.E. Schaefer, B. Kloppenborg, E.O. Waagen, “Recurrent Nova T CrB Has Just Started Its Pre-eruption Dip in March/April 2023, so the Eruption Should Occur Around 2024.4 +- 0.3,” The Astronomer’s Telegram, No. 16107 (2023). The SAO/NASA Astrophysics Data System.His paper concerning his identification of much earlier outbursts ( https://ui.adsabs.harvard.edu/abs/2023JHA….54..436S/abstract ) says:
“T CrB has four observed eruptions in the years 1217.8, 1787.9, 1866.4, and 1946.1, plus one more expected upcoming in 2024.4 ± 0.3. The recurrence timescales are 7 × 81.4, 78.5, 79.7, and likely 78.3 ± 0.3 years. With nine eruptions from 1217.8 to 1946.1, the average recurrence timescale is 80.9 years.”
So the 78.3 +/-0.3 error bar comes from the first paper, not his analysis of the interval between the 4 known eruptions. This average timescale is 80.9 years (no error bar given).Brad’s predictions are based on his assumption that the next eruption will unfold in the same way as the last two (which appear to have identical light curves). But there is no strong astrophysical reason that this should be the case a third time. As I’ve reported previously, other researchers have made predictions for later in 2024 or even Nov 2025. We shall just have to keep on looking.
One team of researchers predicted ‘January 2024’, so that’s been and gone. Whenever T CrB erupts, I predict that I will be clouded out for ~20 days whilst it fades back to mag 10, but the weather will relent during the secondary eruption.
Alex.
In my last reply, the link to the paper by Schaefer on the historical outbursts of T CrB got mangled. It should be:
https://ui.adsabs.harvard.edu/abs/2023JHA….54..436S/abstract(I tried to edit the link 3 times, but each time it got mangled…)
And mangled again! Try this
Thanks Jeremy for clarifying the thinking behind Brad Schaefer’s predicted eruption date of 2024.4 ± 0.3 and the two refs that you pointed to – they both worked fine in the end. The pre-eruption dip looks to be a good harbinger although what happened re. its high state before and after the 1946 event does seem to assume that the object will follow a similar behaviour as last time. We shall see!
btw: Since my earlier message, I have had some useful feedback privately from Graeme Waddington about heliacal rising/setting of stars. It sets a good example of how the BAA Forum can work well.
Richard
Great stuff, Richard.
The canonical theory is that the secondary transfers mass to the white dwarf and at a certain point sufficient material builds up on the surface of the WD to trigger a thermonuclear runway. The problem, of course, is we don’t know how far away from that point we are as we cannot measure it.
It will all become clear with hindsight and this time round we will have the most detailed understanding of the events immediately before and after the eruption to post rationalise it all. At least we now have an additional datapoint from 1946 thanks to Michael Woodman.
I’m meeting Brad Schaefer in November and it will be interesting to hear his latest thinking.
ATel 16912 on “Continued monitoring of activity in T CrB: Rapid intensification of He II and spectroscopic gyrations” discusses recent spectroscopic changes in data from the ARAS group: https://www.astronomerstelegram.org/?read=16912
The overall significance is not clear, though there does appear to be a change in accretion environment and rate around October.
The overall significance is not clear, though there does appear to be a change in accretion environment and rate around October.
it looks like the increase in activity ended abruptly on 19th November. (A selection of Woody Sim’s spectra plus a couple of mine taken early morning showing He II 4686 emission line)
Cheers
RobinAttachments:
An ApJL preprint on ArXiv today reveals the the discovery of a Nova Super-Remnant (NSR) surrounding T CrB. This is only the third known NSR. It at least 200,000 years old. Turning to the forthcoming eruption, the authors predict there will be no fluorescent light echoes seen after T CrB erupts, but there might be dust-scattered, continuum light echoes during the year following the nova eruption.
- You must be logged in to reply to this topic.