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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!
JeremyA paper submitted to AAS Journals and published on ArXiv today considers whether Betelgeuse might have a tiny companion.
The paper titled “Radial Velocity and Astrometric Evidence for a Close Companion to Betelgeuse” is at: https://arxiv.org/abs/2409.11332Hello Ian, the abrupt drop in R ~1.4 mag last week is intriguing. I presume reduction in H-Alpha emission. Be interesting if there are spectra from around the same to see what’s happening there. Jeremy
Following on from Steve Brown’s image of the field of chi Cyg, https://britastro.org/observations/observation.php?id=20240906_212805_d660b28088bb3616, here is the recent light curve of chi. It was at maximum of ~mag 4.2 in early July and is now fading.
Attachments:
Since March 2024, RW Cep has started dimming again as shown in the VSS light curve
Attachments:
An ApJL pre-print “Time-Evolution Images of the Hypergiant RW Cephei During the Re-brightening Phase Following the Great Dimming” appears on ArXiv today: https://arxiv.org/abs/2408.11906
This is a follow-up on the 2022 December Great Dimming episode. The authors present analysis of the re-brightening during 2023. They demonstrate that the west side of RW Cep, initially obscured during the dimming phase, reappeared during the subsequent re-brightening phase and the diameter became larger by 8%. They suggest that the dimming of RW Cep was a result from a recent surface mass ejection event, generating a dust cloud that partially obstructed the photosphere.
It is interesting to see that they present a light curve from 1900 to 2024, and other analyses, which to a great extent relies on amateur observations (from the AAVSO database, which encorporates data from the BAA VSS). This shows the value of long term amateur observations.
RW Cep can readily be monitored with binoculars as it varies between mag ~6.2-7.8 We have obs in the BAA VSS database going back to 1969 made by:
S W Albrighton, C M Allen, M Barrett, B J Beesley, M R Bell, P Bibbings, N M Bone, A Brown, P R Clayton, M Currie, H J Davies, D Dobbs, S J Evans, G Fleming, R B I Fraser, V J Freeman, A Gardner, M Glennon, A Good, T Gough, B H Granslo, D Hale-Sutton, M A Hapgood, W Harris, C Henshaw, T L Heywood, P W Hornby, R K Hunt, G M Hurst, J E Isles, B Jobson, S Johnston, S Koushiappas, M Long, T Lubek, B MacDonald, C Mann, T Markham, L McCalman, I A Middlemist, I Miller, P Mulligan, I P Nartowicz, C Newman, M J Nicholls, W Parkes, J Parkinson, R Pearce, D A Pickup, G Pointer, M Poxon, P Quadt, G Ramsay, D W Robinson, T G Saville, D R B Saw, A Smeaton, D M Swain, M D Taylor, G Thompson, J Toone, C Watkins, J Whinfrey, N White, G Winstanley, J D Wise, W J Worraker, E Yusuf
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
Good to see this coverage of UZ Boo and especially to see the appearance of SH’s. Hopefully these will grow.
The sky here last evening was dreadful: I could only see Vega, Altair and a very coppery Moon.No 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.
