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Thread: Betelgeuse Fainting

  1. #61
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    Quote Originally Posted by antoniseb View Post
    Maybe we could get the MSL Curiosity team to keep an eye on it
    Hmm, one of the orbiters or New Horizons. Wouldn't need a big telescope.

  2. #62
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    Quote Originally Posted by Superluminal View Post
    I predict a major outburst in June, when Betelgeuse is behind the Sun and no one will notice.
    What is the theory behind this prediction?

  3. #63
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    Quote Originally Posted by Hornblower View Post
    What is the theory behind this prediction?
    I think it is a theory developed by some researcher named Murphy.
    As above, so below

  4. #64
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    Quote Originally Posted by Jens View Post
    I think it is a theory developed by some researcher named Murphy.
    The astronomy club I belong to called it the Curse of the Skywatchers.

  5. #65
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    Might be nice to enjoy it in Stereo.
    We know time flies, we just can't see its wings.

  6. #66
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    Betelgeuse May Never Go Supernova

    “We don’t know what Betelgeuse will do or when it will do it," says one scientist.

    Link: Proceedings of the National Academy of Sciences



    Moderation note: Betelgeuse May Never Go Supernova merged into this thread.
    Last edited by PetersCreek; 2020-Feb-07 at 06:01 PM. Reason: Merged threads

  7. #67
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    My understanding is that Betelgeuse is probably less than half the mass required for this direct to black hole process, but yes, who knows for sure until we see more of these events.
    Forming opinions as we speak

  8. #68
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    From the paper: In red supergiants, however, carbon doesn’t burn convectively; this limits neutrino losses and leads to a more extended core with dense material around it.
    To my knowledge, there hasn't been any excess of neutrinos detected coming from Betelgeuse. That would seem to support the possiblity that the star may just implode and disappear. Be interesting to see how bright Betelgeuse gets when it starts brightening.

  9. #69
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    Just read an interesting article posted on another thread by SagittariusAstar about failed Supernova. Betelgeuse may just up and disappear on us.

  10. #70
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    Quote Originally Posted by Superluminal View Post
    From the paper: In red supergiants, however, carbon doesn’t burn convectively; this limits neutrino losses and leads to a more extended core with dense material around it.
    To my knowledge, there hasn't been any excess of neutrinos detected coming from Betelgeuse. That would seem to support the possiblity that the star may just implode and disappear. Be interesting to see how bright Betelgeuse gets when it starts brightening.
    I think we couldn't detect excess neutrinos from Betelgeuse yet, at least not until the last 12 hours or so before it becomes a supernova.
    Forming opinions as we speak

  11. #71
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    I would say that this is science at its best. The astrophysicists are doing increasingly sophisticated work in the theory end, and increasingly powerful instruments are enabling observations of test cases.

    I remember reading in Sky and Telescope maybe 20 years ago that early computer simulations in which the core remained spherically symmetrical refused to explode. They just imploded with very little fireworks. I don't remember much of the detail, but I am guessing that it was convection that supplied the key to getting a bang instead of a whimper.

  12. #72
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    I wonder what are chances of instead of a Supernova, there could be an outburst similar to eta Carina? Somewhere between a classical Nova and a Supernova.

  13. #73
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    Quote Originally Posted by Superluminal View Post
    I wonder what are chances of instead of a Supernova, there could be an outburst similar to eta Carina? Somewhere between a classical Nova and a Supernova.
    The chance is either zero or one. Eta Carina is a double star with a combined mass more than 10 times the estimated mass of Betelgeuse, so my guess is that the chance is zero that these two stars will behave the same way.
    Let me add that I have been until now fairly loose in this thread about allowing extra wide error bars on our understanding of stellar theory. Generally, it is thought that Betelgeuse is a great example of a star exactly in the mass range, rotation rate, and composition to be a fairly normal supernova someday.
    Forming opinions as we speak

  14. #74
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    Quote Originally Posted by antoniseb View Post
    The chance is either zero or one. Eta Carina is a double star with a combined mass more than 10 times the estimated mass of Betelgeuse, so my guess is that the chance is zero that these two stars will behave the same way.
    Let me add that I have been until now fairly loose in this thread about allowing extra wide error bars on our understanding of stellar theory. Generally, it is thought that Betelgeuse is a great example of a star exactly in the mass range, rotation rate, and composition to be a fairly normal supernova someday.
    I've seen a couple of claims that Betelgeuse may have recently (astronomically speaking) consumed a companion star.

  15. #75
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    I want to say the dimming seems to have nearly stabilized, but I don't know where to find reliable measurements of its magnitude or luminosity over the past weeks/months to do my own plots. Does anyone know if such a thing exists online? I mean, I see the partial plots posted by the bot on Twitter and a few other places, but I wanted something simpler and more DIY.

    CJSF
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  16. #76
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    Quote Originally Posted by Superluminal View Post
    I've seen a couple of claims that Betelgeuse may have recently (astronomically speaking) consumed a companion star.
    Ah, got lucky this time.

    ===

    https://ui.adsabs.harvard.edu/abs/20...2654W/abstract

    The Betelgeuse Project: constraints from rotation
    Wheeler, J. Craig ; Nance, S. ; Diaz, M. ; Smith, S. G. ; Hickey, J. ; Zhou, L. ; Koutoulaki, M. ; Sullivan, J. M. ; Fowler, J. M.

    In order to constrain the evolutionary state of the red supergiant Betelgeuse (α Orionis), we have produced a suite of models with zero-age main sequence masses from 15 to 25 M☉ in intervals of 1 M☉ including the effects of rotation. The models were computed with the stellar evolutionary code MESA. For non-rotating models, we find results that are similar to other work. It is somewhat difficult to find models that agree within 1σ of the observed values of R, Teff and L, but modestly easy within 3σ uncertainty. Incorporating the nominal observed rotational velocity, ∼15 km s-1, yields significantly different and challenging constraints. This velocity constraint is only matched when the models first approach the base of the red supergiant branch (RSB), having crossed the Hertzsprung gap, but not yet having ascended the RSB and most violate even generous error bars on R, Teff and L. Models at the tip of the RSB typically rotate at only ∼0.1 km s-1, independent of any reasonable choice of initial rotation. We discuss the possible uncertainties in our modelling and the observations, including the distance to Betelgeuse, the rotation velocity and model parameters. We summarize various options to account for the rotational velocity and suggest that one possibility is that Betelgeuse merged with a companion star of about 1 M☉ as it ascended the RSB, in the process producing the ring structure observed at about 7 arcmin away. A past coalescence would complicate attempts to understand the evolutionary history and future of Betelgeuse.

    ==

    https://ui.adsabs.harvard.edu/abs/20...3106C/abstract

    Is Betelgeuse the Outcome of a Past Merger?
    Chatzopoulos, E.

    We explore the possibility that the star α Orionis (Betelgeuse) is the outcome of a merger that occurred in a low mass ratio (q = M2 /M1 = 0.07-0.25) binary stellar system some time in the past hundreds of thousands of years. To that goal, we present a simple analytical model to approximate the perturbed internal structure of a post-merger object following the coalescence of a secondary in the mass range 1-4 Msun into the envelope of a 15-17 Msun primary. We then compute the long-term evolution of post-merger objects for a grid of initial conditions and make predictions about the luminosity, effective temperature and surface equatorial rotational velocity for evolutionary stages that are consistent with the observed location of Betelgeuse in the Hertzsprung-Russell diagram. We find that if a merger occurred after the end of the primary's main-sequence phase, while it was expanding toward becoming a red supergiant star and with radius 200-500 Rsun, then it's envelope is spun-up to values which remain in a range consistent with the Betelgeuse observations for thousands of years of evolution. We also show that the only scenario that can explain both the fast rotation of Betelgeuse and it's observed large space velocity is one where a binary with q = 0.07-0.25 was dynamically ejected by the parent cluster a few million years ago and then subsequently merged. Our results suggest that a fraction of massive stars with uncharacteristically large rotational velocities during their post-main sequence evolution can be well-modeled by invoking a past merger.
    Do good work. —Virgil Ivan "Gus" Grissom

  17. #77
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    Quote Originally Posted by CJSF View Post
    I want to say the dimming seems to have nearly stabilized, but I don't know where to find reliable measurements of its magnitude or luminosity over the past weeks/months to do my own plots. Does anyone know if such a thing exists online? I mean, I see the partial plots posted by the bot on Twitter and a few other places, but I wanted something simpler and more DIY.

    CJSF
    Have you checked out the AAVSO site?
    https://www.aavso.org/apps/webobs/re...um_results=200

  18. #78
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    Quote Originally Posted by CJSF View Post
    ... Does anyone know if such a thing exists online?...
    https://www.aavso.org/lcg fill out the form to give lots of pixels in the result... I do 1600x1600, also select most of the bands to see several views. I suspect that the blue magnitudes are the best indicator with the least uncertainty of measurement, but the visible estimates are the most plentiful. I also agree that it seems to have nearly stabilized, but the Moon is still close enough to Orion to potentially make comparisons to Bellatrix or the belt stars imprecise. In a few days we'll get a better read.
    Forming opinions as we speak

  19. #79
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    Thanks you two!

    CJSF
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    Electrons are free
    (Plasma!) Fourth state of matter
    Not gas, not liquid, not solid"

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  20. #80
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    Hm.. is there an option to get a single plotted curve/line as a function of all those inputs? A trend line, is it called? I don't see one. These plots are cool and useful, but I could use something cleaner looking for explanatory purposes for the less astronomically and statistically inclined members of my family and my friends.

    [ETA: I see an option for the curve I think, but can't get it to display as I think it should. But it's there, so the problem is me. So never mind the above. Thanks again!]

    CJSF
    Last edited by CJSF; 2020-Feb-08 at 01:11 AM. Reason: derp. found what I was looking for - ish.
    "The sun is a quagmire
    It's not made of fire
    Forget what you've been told in the past
    Electrons are free
    (Plasma!) Fourth state of matter
    Not gas, not liquid, not solid"

    -They Might Be Giants, "Why Does The Sun Really Shine?"


    lonelybirder.org

  21. #81
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    One thing I've noticed on the AAVSO visual can be all over the place. Sometimes a change of .5 mag. in less than an hour. Most likely due to the skill and experience of the observer. As well as seeing conditions. I've made my own hand drawn light curve. The trend line is running a bit below 1.5. My most recent observation, 9:20pm, full moon and thin haze, Betelgeuse appeared to be fainter than Bellatrix. Our eyes are more sensitive to blue light. I believe that would make Betelgeuse a bit bright than Bellatrix.

  22. #82
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    Quote Originally Posted by Superluminal View Post
    I wonder what are chances of instead of a Supernova, there could be an outburst similar to eta Carina? Somewhere between a classical Nova and a Supernova.
    You could certainly have an outburst first, and then much later a supernova. That seems pretty likely, actually. It's also possible it won't supernova, and it also won't collapse into a black hole-- it might just make a neutron star, but no explosion. We really have no idea how often that might happen, because the statistics of supernovae we see, and pulsars we detect, is so sparse, and the scenarios represented are so diverse. If you think the simulations are a representative sample of what can happen, you would conclude that explosions are relativity rare! But of course the simulations are still of uncertain reliability given that they must make significant simplifications and are not designed to be a complete rendering of everything that is happening.
    Last edited by Ken G; 2020-Feb-08 at 03:02 PM.

  23. #83
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    Quote Originally Posted by antoniseb View Post
    Generally, it is thought that Betelgeuse is a great example of a star exactly in the mass range, rotation rate, and composition to be a fairly normal supernova someday.
    Actually, one can't really say that. The problem is that supernova theory is centered around this question: "why are massive stars sometimes observed to explode?" No supernova theory is based around the question, "do massive stars always explode?" or even "do massive stars usually explode?" Given that the question of what they might be doing when they explode is already very theoretically challenging, you can see that we are nowhere near being able to answer that last question!

  24. #84
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    https://www.spaceweather.com/images2...urve_strip.png
    The most recent measurements put the magnitude of Betelgeuse at about +1.66, the dimmest its been in our 25 years of photometery," says Edward Guinan of Villanova University.
    Answers might be forthcoming on Feb. 21st. Astronomers have long known that Betelgeuse is a variable star.
    If Betelegeuse starts to bounce back on Feb. 21st, this whole episode might just be a deeper-than-average pulsation, and perhaps the supernova watch can be called off. However, notes Guinan, "even if the 430-day period is still working, this would indicate a minimum brightness near 0.9 mag--much brighter than the current value near 1.6 mag. So something very unusual is going on."

    Stay tuned for updates as Feb. 21st approaches.

  25. #85
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    Quote Originally Posted by Superluminal View Post
    https://www.spaceweather.com/images2...urve_strip.png
    The most recent measurements put the magnitude of Betelgeuse at about +1.66, the dimmest its been in our 25 years of photometery," says Edward Guinan of Villanova University.
    Answers might be forthcoming on Feb. 21st. Astronomers have long known that Betelgeuse is a variable star.
    If Betelegeuse starts to bounce back on Feb. 21st, this whole episode might just be a deeper-than-average pulsation, and perhaps the supernova watch can be called off. However, notes Guinan, "even if the 430-day period is still working, this would indicate a minimum brightness near 0.9 mag--much brighter than the current value near 1.6 mag. So something very unusual is going on."

    Stay tuned for updates as Feb. 21st approaches.
    Why Feb. 21?

  26. #86
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    For the past few nights I have been seeing Betelgeuse as roughly equal to Bellatrix, subject to the uncertainty that is the nature of the beast. When I stare at them long enough Betelgeuse appears to brighten a bit, in keeping with the Purkinje effect. When I first looked six weeks ago, in response to the OP, Betelgeuse looked slightly brighter, though closer to Bellatrix than to Aldebaran.

  27. #87
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    I've been using Bellatrix and Pollux as comparison stars. The last couple of nights they appear to be equal in mag. In good agreement with the Villanova results. On my personal light curve I've made, based on AAVSO visual observations, the last week of January there a lot of observations above the +1.5 magnitude line. The first 8 days of February only 3 observations above the +1.5 magnitude line.

    As for Hornblower's question: Why February 21st? That's the bottom of the 400 day sub cycle. If Betelgeuse acts normal, it should start brightening after the 21st.

  28. #88
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    Quote Originally Posted by Superluminal View Post
    I've been using Bellatrix and Pollux as comparison stars. The last couple of nights they appear to be equal in mag. In good agreement with the Villanova results. On my personal light curve I've made, based on AAVSO visual observations, the last week of January there a lot of observations above the +1.5 magnitude line. The first 8 days of February only 3 observations above the +1.5 magnitude line.

    As for Hornblower's question: Why February 21st? That's the bottom of the 400 day sub cycle. If Betelgeuse acts normal, it should start brightening after the 21st.
    Thanks for the heads-up. I will keep watching until Orion disappears behind the Sun.

  29. #89
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    The new red and blue filtered measurements both are back down at levels from below the Moonlight problem days (within 0.05 mag of the lowest ever reported, which was last week). There had been wider uncertainty drifting higher during the close Moon.
    Forming opinions as we speak

  30. #90
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    Article from 3 hours ago saying Betelgeuse is still "acting weird". Something about a hot spot being detected.

    https://www.space.com/how-to-see-bet...able-star.html
    Do good work. —Virgil Ivan "Gus" Grissom

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