Betelgeuse

Forums General Discussion Betelgeuse

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  • #585159
    Jeremy Shears
    Participant

    The Great Dimming of Betelgeuse is still eliciting papers on what caused it, such as this one submitted to the MNRAS. The title asks “Did a close tidal encounter cause the Great Dimming of Betelgeuse?” and although the answer (spoiler alert!) seems to be “probably not”, it’s still an interesting read. 

    #585161
    Jeremy Shears
    Participant

    Thanks Tim. Another interesting paper.

    (For some reason, clicking the ArXiv linked brought up an error message for me; the link that worked for me is here)

    #585160
    Tim Parsons
    Participant

    Thanks for the link Jeremy. Yet another recent one (with somewhat more enlightening conclusions regarding RSG mass-loss mechanisms) is from Roberta Humphreys and Terry Jones at UMinn. It can be found at: https://arxiv.org/abs/2201.07818

    This includes discussion of Betelgeuse and comparisons with the hypergiant VY CMa.

    #585162
    Tim Parsons
    Participant

    Cheers Jeremy – it was my fault as I just noticed I had added a blank space at the end! I think it works from my original post now as well…

    #585166
    Jeremy Shears
    Participant

    Another paper (reprint from Nature) on ArXiv: A dusty veil shading Betelgeuse during its Great Dimming

    #585267
    Jeremy Shears
    Participant

    An A&A preprint on ArXiv today reports the first 3D imaging of Betelgeuse, revealing massive convection cells.

    Frustratingly, especially for the authors, their equipment was being upgraded during the “great fade” at the end of 2019/early 2020, so this was missed!

    #585268
    Daryl Dobbs
    Participant

    Interesting prediction in the attachment below outlining a possibility of a fade in June.

    ATel #15240: The brighter phase of Betelgeuse since 2017 (astronomerstelegram.org)

    #613546
    Jeremy Shears
    Participant

    Incredible as it may seem, it’s almost 3 years since the Great Dimming of Betelgeuse first hits the news. New papers continue to be published on the star, including a couple on the last 2 days:

    UBVRI photometry of Betelgeuse over 23 years since 1999
    Yojiro Ogane, Osamu Ohshima, Daisuke Taniguchi, Naohiro Takanashi
    https://arxiv.org/abs/2211.04512

    Analysis of photometric and spectroscopic variability of red supergiant Betelgeuse
    Daniel Jadlovsky, Jiri Krticka, Ernst Paunzen, Vladimir Stefl
    https://arxiv.org/abs/2211.04380

    The second paper says that after the Dimming, the Betelgeuse mode of variability has fundamentally changed and is now instead following a shorter period of ∼200d (cf ~400+d, plus several longer periods, in previous epochs)

    #620500
    Jeremy Shears
    Participant

    Another year on: now 4 years from the Great Dimming!

    An A&A preprint appears on ArXiv today (https://arxiv.org/abs/2312.02816) shows how different layers in the star’s photosphere appeared pourturbed during the event, returning to normal in 2022.

    The Great Dimming of Betelgeuse: the photosphere as revealed by tomography during the past 15 years

    Daniel Jadlovský, Thomas Granzer, Michael Weber, Kateryna Kravchenko, Jiří Krtička, K. Andrea Dupree, Andrea Chiavassa, G. Klaus Strassmeier, Katja Poppenhäger

    Betelgeuse, a red supergiant star of semi-regular variability, underwent a historical minimum of brightness in February 2020, the Great Dimming. Even though the brightness has returned to the values prior to the Great Dimming by now, it continues to exhibit highly unusual behavior. Understanding the long-term atmospheric motions of Betelgeuse and its variability could be a clue to the nature of the Great Dimming and the mass-loss process in red supergiants. Our goal is to study long-term dynamics of the photosphere. We applied the tomographic method, which allows different layers in the stellar atmosphere to be probed in order to reconstruct depth-dependent velocity fields. The method is based on the construction of spectral masks by grouping spectral lines from specific optical depths. These masks are cross-correlated with the observed spectra to recover the velocity field inside each atmospheric layer. We obtained about 2700 spectra during the past 15 years, observed with the STELLA robotic telescope in Tenerife. We analysed the variability of 5 different layers of Betelgeuses photosphere. We found phase shift between the layers, as well as between the variability of velocity and photometry. The time variations of the widths of the cross-correlation function reveal propagation of two shock waves during the Great Dimming. For about 2 years after the Dimming, the time scale of variability was different between the inner and outer photospheric layers. By 2022, all the layers seemingly started to follow a similar behavior as before the Dimming, but pulsating with higher frequency corresponding with the first overtone. Combination of the extensive high-resolution spectroscopic data set with the tomographic method revealed the variable velocity fields in the photosphere of Betelgeuse, for the first time in such detail.

    #620505
    Alex Pratt
    Participant

    A while after 01:00 UT on December 12 Betelgeuse will be occulted by asteroid (319) Leona. It’s very rare for such a bright star to be occulted and this ‘once in a lifetime’ event will be used to model the photosphere of Betelgeuse.

    Recent occultations of other stars by Leona have determined its dimensions, showing that it subtends (perhaps) a slightly smaller apparent diameter than Betelgeuse, giving a partial / annular occultation of 11s duration. The 142 km-wide shadow track passes over China, Turkiye, Greece, Italy, Spain, Portugal and southern Florida (USA), and more than 80 observers are participating in this pro-am campaign. They will record the occultation using various filters and some teams plan to obtain high resolution spectra.

    https://proam-gemini.fr/photometrie-et-spectroscopie-de-betelgeuse-%CE%B1-ori-lors-de-son-occultation-par-319-leona-du-12-12-2023/

    https://call4obs.iota-es.de/2023-dec-12-0110-ut-319-leona-occults-betelgeuse-alpha-orionis-0-5-mag

    Alex.

    • This reply was modified 7 months, 1 week ago by Alex Pratt.
    #620537
    Alex Pratt
    Participant


    On https://www.virtualtelescope.eu/webtv/

    Gianluca Masi, Italian astronomer and developer of “THE VIRTUAL TELESCOPE PROJECT”,
    has posted the following announcement :

    Next event: “Betelgeuse occultation by Leona: live view” –
    12 Dec. 2023, starting at 01:00 UTC

    #620570
    Jeremy Shears
    Participant

    More on the Betelgeuse occultation here: https://www.astronomerstelegram.org/?read=16374

    #620641
    Mr Ian David Sharp
    Participant

    Hi all,

    It looks like the occultation track of Leone tonight passes over my telescope at PixelSkies in Spain.

    Having a C11 with an SX694 TRIUS CCD, I can’t take short, rapid exposures a la a CMOS camera, so my plan is to let it drift across the FOV. I will experiment first with am R filter but I suspect it will easily saturate. Then I will try an SII. All slightly off focus I think.

    Any other tips?

    Cheers
    Ian.

    #620642
    Alex Pratt
    Participant

    Hi Ian,

    Drift is a good option. Driftscan software can process your capture. Please record for about 1 minute before and after the mid-time given by the Interactive Map of the Paris ‘Lucky Star’ prediction

    https://lesia.obspm.fr/lucky-star/occ.php?p=131608

    Avoid saturation at all costs. If you can’t apply a ‘many-holes mask’ as suggested in the last-minute advice (above), try your R or SII filter with a brief exposure time. A H-alpha would attenuate the light, if available. A small amount of defocus is fine.

    Take darks and flats.

    Good luck,

    Alex (in Alicante)

    • This reply was modified 7 months ago by Alex Pratt.
    #620644
    Dr Paul Leyland
    Participant

    Reviewing this thread, I noticed that no-one had spotted the obvious answer to my professionals bugging amateurs quip.

    What will likely happen is that everyone will send out to the local hardware shop for a big enough piece of plywood to cover the aperture and then cut a small diameter hole in it.

    #620663
    Alex Pratt
    Participant

    Even if you cannot avoid image saturation, your data could be valuable. Most setups for this event are configured to monitor the descending and ascending branches of the light curve. A camera that is saturated before the occultation could contribute data on the deepest part of the brightness dip, particularly if it’s >2 or 3 magnitudes.

    Alex (in Alicante)

    #620666
    Mr Ian David Sharp
    Participant

    Drift is a good option. Driftscan software can process your capture. Please record for about 1 minute before and after the mid-time given by the Interactive Map of the Paris ‘Lucky Star’ prediction

    Thanks Alex,

    I’m experimenting now. I can record (drift) for just over a minute which will be only 30 seconds or so either side of my predicted mid time. The only filter that does not saturate is my OIII giving me ADU values of about 30,000.

    Cheers
    Ian.

    #620670
    Mr Ian David Sharp
    Participant

    Well, here’s my 60 second drift image with an OIII filter. I had no saturation (this image is slightly stretched). I see no sign of any dimming.

    Cheers
    Ian.

    Attachments:
    #620672
    Michael O’Connell
    Participant

    Folks,
    My initial thoughts after successfully observing the occultation last night:
    ————————————————————

    Through hazy skies, we (myself and Alex Pratt) had a successful observation of the occultation of Betelgeuse from just south of Alicante, near the airport.
    My personal thoughts from visually observing it are:

    Skies consisted of variable levels of haze, which made the observation more challenging (and head-wrecking) that I would have liked.
    The dimming was not sudden like a typical occultation, but rather quite gradual which appeared to take approx 2-3 seconds.
    The star appeared to dim by approx 1 to 2 magnitudes – quite noticeable.
    The rise was more difficult to detect visually due to the haze.
    I was expecting it to remain at its faintest magnitude for a period of time, and was surprised to see it brightening almost immediately after reaching minimum magnitude.
    Attached is a handheld photo of Orion taken during the event with an iphone.
    Also attached is a screenshot of a lightcurve taken with my Watec 910 HX/RC and 40mm f/4.5 apo with Bessel V filter.

    ————————————————————
    Regards,
    Michael

    #620676
    Mr Ian David Sharp
    Participant

    Folks,
    My initial thoughts after successfully observing the occultation last night:

    Excellent! Certainly more interesting than my drift trail!

    Cheers
    Ian.

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