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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.
This is definitely feasible. Arne Henden is routinely monitoring T CrB in daylight. He is using a Newtonian stopped down to 50mm and is able to image theta CrB mag ~4.1. The other day there was a false alarm and he was able to show that there was nothing brighter than mag ~4.5.
The rise time is 1-5 hours.
Latest data shows that the rebrightening episode, which lasted ~9 days, is now over with the star having faded to 18th mag. Additional rebrightenings are possible.
Many people enjoyed the nova V1674 Her that erupted in 2021 (was it really that long ago?). A pre-print of an ApJ paper has just appeared which probes the early part of the eruption in unprecedented detail, shedding now light on the events at the white dwarf that triggered the eruption.
Thanks Ian. I note that the star dipped (to mag 16) and re-brightened ~4 days ago. Classic UGWZ. I wonder if there will be further such episodes.
Tonny Vanmunster reports the emergence of 0.16 mag amplitude humps 13 days into the outburst of this putative UGWZ dwarf nova. The period is ~0.067 days.
Spectroscopy from the GOTO team leads them to suggest this is a WZ Sge type dwarf nova: https://www.astronomerstelegram.org/?read=16858
If so, one might expect superhumps to develop.
LHAASO also reports gamma ray flaring on Oct 5: https://www.astronomerstelegram.org/?read=16850
Looking at the AAVSO light curve, it was ca 0.5 mag brighter in BVRI (13.2V) on Oct 6 compared to Oct 3.
Gamma ray observations from Fermi LAT show enhanced gamma ray emissions on Oct 5
https://www.astronomerstelegram.org/?read=16849Gamma ray light curve: https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/BL_Lac
Good to see the data coming in.
I also see an ATel from the ARIES team in India: https://www.astronomerstelegram.org/?read=16847Let’s hope it gets a proper name soon. Good publicity for the GOTO project(Gravitational-wave Optical Transient Observer)
It’s worth pointing out that the lead author on the ATel is Dr Thomas Killestein: https://tkilleste.in/
Thomas was recipient of the Sir Patrick Moore Prize 2016. I well remember presenting it to him at the 2017 January meeting: https://britastro.org/2017/young-astronomer-awarded-the-2016-sir-patrick-moore-prize
There is a further confirmation here: https://www.astronomerstelegram.org/?read=16847
There is an interesting paper, submitted to A&A, on last May’s solar storm involving multiple interacting coronal mass ejections.
“Unveiling Key Factors in the Solar Eruptions Leading to the Solar Superstorm in 2024 May“
I’ve been asked about availability of the book. It’s published by MIT Press: https://mitpress.mit.edu/9780262049382/attention-is-discovery/
Available through Amazon.
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.
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
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.
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!
Jeremy
