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Now in the national news.
Michael Woodman was interviewed on the BBC World Service news this morning about his discovery of the 1946 eruption of T CrB.
I have invited him to attend the January BAA meeting to receive the Charles Butterworth award of the VSS.
An A&A preprint on ArXiv today discusses the recent super-active phase SAP of T CrB.
The SAP lasted between 2015 and 2023, during which T was about three-quarters of a magnitude brighter than normal. A similar SAP was observed prior to the 1946 eruption.
The authors find that the SAP was triggered in the inner part of the accretion disc, increasing the disc temperature and the mass accretion rate at the white dwarf surface. The higher temperature should have further enhanced the mass transfer and sustained the SAP.
The SAP abruptly stopped in 2023, implying that the disc has returned to a quiet phase. At this time accretion dropped to a very low level. Recently T has been gradually brightening again and accretion has picked up. Note that when sufficient material has accumulated on the surface of the white dwarf, it triggers the thermonuclear runaway that appears as a nova eruption.
Michael Woodman, who independently discovered the 1946 eruption of T CrB as a 15-year old schoolboy in 1946, was guest of honour at the BAA meeting on January 18. He was presented with the BAA VSS Charles Butterworth Award.
Many thanks to all those present who helped to make it as special day for Michael and his family.
A photo of Michael (taken by Philip Jennings) is attached.
Attachments:
Jeremy,
It was very pleasing that Michael and his family could attend the meeting on Saturday, and I saw how much they enjoyed your presentation – ‘British Independent Discoveries of the 1946 Eruption of T Coronae Borealis’.
Alex.
It was fantastic to see Michael Woodman in person, and really great that many members of his family were able to attend the presentation of his Butterworth Award.
In answer to a question following my talk on T CrB, I mentioned that some had predicted that the neutrino burst from the eruption might just be detectable on Earth. However, a pre-print on ArXiv today suggests that the burst might actually be too weak for such a detection.
As ever, time will tell.
An ATel today reports an increase in accretion rate in the last couple of weeks: https://www.astronomerstelegram.org/?read=17030
An AAS research note has been issued discussing the similar short term flare event seen in amateur spectroscopic observations during November 2024
https://iopscience.iop.org/article/10.3847/2515-5172/adb425
(It is possible that these are common during the low state but may not be picked up due to observing cadence)Cheers
RobinNot wishing to get people’s hopes up, but this interesting ATel #17041 was released just a few moments ago.
Gary
Not wishing to get people’s hopes up, but this interesting ATel #17041 was released just a few moments ago.
The spectrum from the ARAS database showing the increase in H alpha emission taken on 7th of February that they refer to is mine, though I have no connection with the team. (If this was my ATel I would definitely be putting a question mark at the end of the title !)
There are actually high resolution H alpha spectra close to all three dates in ARAS database
https://aras-databas…abase/tcrb.htm
See attached. Mine showing the increase in emission is in black.I am sceptical about any predictions of TCrB base on accretion rate though which varies continuously in all timescales. For example attached is a spectrum in the ARAS database from from Francois Teyssier taken in 2021 when it was in a continuous high state which shows the same H alpha intensity as my Feb 7th spectrum. Of course then again it might blow tonight ! We do urgently need more spectra though and unfortunately I have been clouded out since.
Cheers
RobinThis AJ preprint on ArXiv predicts that T CrB will become the brightest nova ever observed in X-Ray: https://arxiv.org/abs/2502.10925
The authors also discuss the future evolution of the white dwarf towards the Chandrasekhar limit.
A paper on the “Binary Parameters for the Recurrent Nova T Coronae Borealis” today reports the masses of the white dwarf and the red giant that comprise this binary system. The authors conclude that the WD mass is 1.37 +/- 0.01 M-sun. This would place it close to the Chandrasekhar instability limit.
Have you seen this Jeremy? Has more than a whiff of numerology about it. Of course I do not believe in numerology, checks my diary for March 27th. https://www.researchgate.net/publication/385381254_When_will_the_next_T_CrB_eruption_occur
Yes I am familiar with that analysis Steve. I can’t think of an astrophysical reason why there should be a fixed number of orbits between eruptions.
I checked CrB on Sunday evening- still no sign of T CrB in outburst. I’ll make a proper observation of it tonight.
I have started to use my Seestar S50 as a robotic telescope to keep an unattended “eye” on T CrB. It will start observing at 01:00 GMT when the telescope gets a clear LOS on T CrB (from where I can keep it safe) and it will record images for ca 3 hrs atm, and then shut down again, powered by an external powerbank (so I’m not wearing out the internal batteries so much). An errupting T CrB would probably saturate the sensor soonish, but at least I could, when lucky, contribute the initial erruption and some part of the pre-erruption phase.
As the sub-frames are accessible to other computers on my home network (as the Seestar S50 shares it’s storage in the local network as a network drive) it would in theory be possible to script something that would actually monitor T CrB in real-time, unattended, during all of this. Has anyone done this kind of scripting already?
Clear Skies
Heinz-Bernd EggensteinI to would be very interested in such a script. Have been using a Seestar to keep on eye on T CrB since June whenever circumstances allow. As of this morning I have 25,094 images of T CrB not in outburst. I am now using an S30 instead of an S50 which I think gives better results. Fewer rejected frames due to shorter focal length and smaller aperture means the sensor would saturate later when it goes into its long awaited outburst.
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