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Changes in periods of Miras is a very active field of research as it might shed further light on stellar evolution in the Asymptotic Giant Branch (AGB) of the HR diagramme. One popular view is that period decrease is due to contraction during the initial stage of the thermal pulse in the helium burning shell, as you indicate.
Another period changer is T UMi. Coincidently there is an MRAS pre-print on ArXiv only today on “Hydrodynamic modelling of pulsation period decrease in the Mira-type variable T UMi” which pursues the matter. It considers hydrodynamic models and non–linear stellar pulsations. The references therein are worth following: https://arxiv.org/abs/2206.08360
Keeping up with ideas and literature in this area could be a fulltime job, but we are lucky to have the monthly AGB Newsletter to help us as it summarises recent literature. You can subscribed to it here: https://www.astro.keele.ac.uk/AGBnews/
The June edition is the 299th, and celebrations are promised for the July edition. It is available here: https://www.astro.keele.ac.uk/AGBnews/issues/AGB299.pdf
The last chapter on this fascinating topic has yet to be written! But it is interesting to note that the research, and the associated models, depend on amateur observations of Miras over many years.
No problem submitting, Max. Researchers can subsequently apply any data quality selection criteria they wish. Without any data they have no choice. The other consideration is that your data, at the very least, provide a snapshot of the system status at that time.
Multiple confirmations of the eruption have appeared overnight. Appears to be around maximum (8th mag).
In the 2010 eruption, it faded one mag in a day and 6 mags in 4 days. Let’s hope we get a break in UK skies (I’ve not seen any UK obs yet)
Charts here: https://app.aavso.org/vsp/chart/?star=U%20SCO&fov=60&maglimit=14.5&resolution=150&north=up&east=left
Can be scaled/orientated to choice
Worth looking for quiescence eclipses, Max. Accretion disc might be smaller then and thus more easily eclipsed
This nova is still being observed and still relatively bright at 11th mag. Worth following. What will it do next?
Light curve from the VSS database:Attachments:
Thanks Max. There’s a lot of variation there. Not sure it’s regular though. Time will tell.
Keep up the good work!Go well!
JeremyStarlight Nights is available on Kindle, Daryl. Not the same as having the book, but at least you can enjoy it and be reminded why we love astronomy so much.
I think I was 14 when I first read it. Our Eng Lit master said we should read a book of our choice (“not a textbook on astronomy, Shears!”) and write about it afterwards. I found it in the village library. I must have renewed its loan many times. And fortunately it’s not textbook.
There was a meeting planned in 2020, but a global pandemic put paid to that.
These things needs a lot of planning and organising. Hopefully next year.
The nova, V1674 Her, is still 3-4 magnitudes above quiescence (latest entry in VSS database: Apr 2 at mag 16.7 by Nick James) as shown in the accompanying light curve. Well worth following now that Hercules is more readily accessible. As Prof Joe Patterson (Columbia U and Center for Backyard Astrophysics) noted: “We are just getting started on this amazing star… and I bet others are, too. In the history of novae, I think it will take a high place in the pantheon, alongside DQ Her, T Pyx, and V1500 Cyg”
A recent ATel (https://www.astronomerstelegram.org/?read=15312) said optical spectroscopy suggests it has returned to quiescence, which is curious since the progenitor was 20.5g. The final chapter on this neon nova is far from being written…..
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