Betelgeuse Fainting

[Superluminal]

https://www.iflscience.com/space/bet...lode-probably/
Betelgeuse,\alpha Orionis, has never been this faint since records have been kept. But a supernova isn't expected anytime soon.

[profloater]

possibly! a supernova now would be a boost. And one of the best known stars, so easy to find.

[Jens]

possibly! a supernova now would be a boost. And one of the best known stars, so easy to find.

Though if it went supernova, it would be a lot, lot easier.


Sent from my iPhone using Tapatalk

[Trebuchet]

That's certainly a usage of "fainting" that is new to me! Perhaps Orion has adjusted something in his garb to cover it.

[George]

That's certainly a usage of "fainting" that is new to me! Perhaps Orion has adjusted something in his garb to cover it.

I'll raise your "fainting" with Cotton Candy planets.

[Hornblower]

Go to this site
https://earthsky.org/space/betelgeus...out-to-explode
and scroll down to an AAVSO chart for the past century, as posted by a responder in that site. The current faint spell looks like nothing out of the ordinary so far.

[Hornblower]

I just now took a look. Betelgeuse looks somewhat fainter than Aldebaran and perhaps a hair brighter than Bellatrix. The color contrast makes the latter comparison somewhat uncertain. I have seen Betelgeuse as bright as Procyon, about a whole magnitude brighter than now.

[Superluminal]

I've read that when comparing the mag. Of a red and blue star of ~equel mag. The red star will appear fainter.

[Superluminal]

I've read that when comparing the mag. Of a red and blue star of ~equel mag. The red star will appear fainter.

[Glom]

That's true of anything red.

[George]

I've read that when comparing the mag. Of a red and blue star of ~equel mag. The red star will appear fainter.

As my wife says, "exactly the same but different". What is the "different" part here? Are you comparing visual magnitudes to bolometric magnitudes? If so, there are correction factors to convert one to another and color is a big part of that.

[ngc3314]

One of the many visual effects to be aware of when trying to use the eye for numerical brightness measurements - the longer you stare at a red star, the brighter it will appear compared to a blue star similarly observed (the Purkinje effect). This effect can be reduced by defocusing the telescope so the stars are seen as disks with surface brightness too low to see color. You should also be careful to compare stars only "horizontally", rotating your view so they are seen parallel to the line between your eyes, because for most people there is either a sensitivity or "processing" gradient related to the fat that so may everyday scenes have a lot of vertical brightness gradients. These are described in chapter 3 of the AAVSO visual observer's manual.

(For Betelgeuse, for some observers the defocussing trick just requires pulling glasses off; otherwise it may take enough muscle effort to
distract from the task at hand.)

[Hornblower]

Let's make sure we do not jump to premature conclusions that this current faint spell is indicative of a core collapse that is going to happen sooner rather than later. It is my understanding that when the last of the exothermic fusible stuff in the core is used up, the collapse will be sudden, running its course in a matter of seconds and blowing up the envelope in a few hours. Fluctuations such as we observe are from relatively superficial instabilities in the envelope, far removed from the core.

Don't take my remarks as gospel. As is so often the case my memories of sources are over past decades and I don't have the "Google-fu" to chase them down, even if it is possible to do so. Any contribution from others is most welcome. A reference librarian at a college or university astronomy library would be a big help.

[Roger E. Moore]

Detecting neutrinos and antineutrinos seems to be the recommended way to go for Type II supernova prediction. You might get up to half a day's warning. These recent papers reference Betelgeuse.

https://arxiv.org/abs/1908.07551

Sensitivity of Super-Kamiokande with Gadolinium to Low Energy Anti-neutrinos from Pre-supernova Emission
C. Simpson, K. Abe, C. Bronner, Y. Hayato, M. Ikeda, H. Ito, et al.
(Submitted on 20 Aug 2019 (v1), last revised 26 Sep 2019 (this version, v2))

Supernova detection is a major objective of the Super-Kamiokande (SK) experiment. In the next stage of SK (SK-Gd), gadolinium (Gd) sulfate will be added to the detector, which will improve the ability of the detector to identify neutrons. A core-collapse supernova will be preceded by an increasing flux of neutrinos and anti-neutrinos, from thermal and weak nuclear processes in the star, over a timescale of hours; some of which may be detected at SK-Gd. This could provide an early warning of an imminent core-collapse supernova, hours earlier than the detection of the neutrinos from core collapse. Electron anti-neutrino detection will rely on inverse beta decay events below the usual analysis energy threshold of SK, so Gd loading is vital to reduce backgrounds while maximising detection efficiency. Assuming normal neutrino mass ordering, more than 200 events could be detected in the final 12 hours before core collapse for a 15-25 solar mass star at around 200 pc, which is representative of the nearest red supergiant to Earth, α Ori (Betelgeuse). At a statistical false alarm rate of 1 per century, detection could be up to 10 hours before core collapse, and a pre-supernova star could be detected by SK-Gd up to 600 pc away. A pre-supernova alert could be provided to the astrophysics community following gadolinium loading.

===

https://arxiv.org/abs/1906.06839

Presupernova neutrino signals as potential probes of neutrino mass hierarchy
Gang Guo, Yong-Zhong Qian, Alexander Heger
(Submitted on 17 Jun 2019)

We assess the potential of using presupernova neutrino signals at the Jiangmen Underground Neutrino Observatory (JUNO) to probe the yet-unknown neutrino mass hierarchy. Using models for stars of 12, 15, 20, and 25 solar masses, we find that if the electron antineutrino signals from such a star can be predicted precisely and the star is within ~440-880 pc, the number of events of electron antineutrino captures on protons detected within one day of its explosion allows to determine the hierarchy at the > ~95% confidence level. For determination at this level using such signals from Betelgeuse, which is at a distance of ~222 pc, the uncertainty in the predicted number of signals needs to be < ~14-30%. In view of more realistic uncertainties, we discuss and advocate a model-independent determination using both electron neutrino and antineutrino signals from Betelgeuse. This method is feasible if the cosmogenic background for neutrino-electron scattering events can be reduced by a factor of ~2.5-10 from the current estimate. Such reduction might be achieved by using coincidence of the background events, the exploration of which for JUNO is highly desirable.

===-

https://arxiv.org/abs/1905.09283

Pre-Supernova Neutrinos in Large Dark Matter Direct Detection Experiments
Nirmal Raj, Volodymyr Takhistov, Samuel J. Witte
(Submitted on 22 May 2019 (v1), last revised 30 May 2019 (this version, v2))

The next Galactic core-collapse supernova (SN) is a highly anticipated observational target for neutrino telescopes. However, even prior to collapse, massive dying stars shine copiously in 'pre-supernova' (pre-SN) neutrinos, which can potentially act as efficient SN warning alarms and provide novel information about the very last stages of stellar evolution. We explore the sensitivity to pre-SN neutrinos of large scale direct dark matter detection experiments, which, unlike dedicated neutrino telescopes, take full advantage of coherent neutrino-nucleus scattering. We find that argon-based detectors with target masses of O(100) tonnes (i.e. comparable in size to the proposed ARGO experiment) can detect O(10−100) pre SN neutrinos coming from a source at a characteristic distance of ∼200 pc, such as Betelgeuse (α Orionis). For such a source, large scale dark matter experiments could provide a SN warning siren ∼10 hours prior to the explosion. We also comment on the complementarity of large scale direct dark matter detection experiments and neutrino telescopes in the understanding of core-collapse SN.

[Roger E. Moore]

Last batch of type-II supernova documents from second half of this year. I'll cut off at this. Much good reading here.

https://arxiv.org/abs/1911.11450
Expanding Core-Collapse Supernova Search Horizon of Neutrino Detectors
Odysse Halim, Carlo Vigorito, Claudio Casentini, Giulia Pagliaroli, Marco Drago, Viviana Fafone
(Submitted on 26 Nov 2019 (v1), last revised 10 Dec 2019 (this version, v3))
Core-Collapse Supernovae, failed supernovae and quark novae are expected to release an energy of few 10^53 ergs through MeV neutrinos and a network of detectors is operative to look online for these events. However, when the source distance increases and/or the average energy of emitted neutrinos decreases, the signal statistics drops and the identification of these low statistic astrophysical bursts could be challenging. In a standard search, neutrino detectors characterise the observed clusters of events with a parameter called multiplicity, i.e. the number of collected events in a fixed time-window. We discuss a new parameter called ξ (=multiplicity/duration of the cluster) in order to add the information on the temporal behaviour of the expected signal with respect to background. By adding this parameter to the multiplicity we optimise the search of astrophysical bursts and we increase their detection horizon. Moreover, the use of the ξ can be easily implemented in an online system and can apply also to a network of detectors like SNEWS. For these reasons this work is relevant in the multi-messengers era when fast alerts with high significance are mandatory.

https://arxiv.org/abs/1911.10656
Detectability of SASI activity in supernova neutrino signals
Zidu Lin, Cecilia Lunardini, Michele Zanolin, Kei Kotake, Colter Richardson
(Submitted on 25 Nov 2019)
We introduce a novel methodology for establishing the presence of Standing Accretion Shock Instabilities (SASI) in the dynamics of a core collapse supernova from the observed neutrino event rate at water- or ice-based neutrino detectors. The methodology uses a likelihood ratio in the frequency domain as a test-statistics; it is also employed to assess the potential to estimate the frequency and the amplitude of the SASI modulations of the neutrino signal. The parameter estimation errors are consistent with the minimum possible errors as evaluated from the inverse of the Fisher information matrix, and close to the theoretical minimum for the SASI amplitude. Using results from a core-collapse simulation of a 15 solar-mass star by Kuroda et al. (2017) as a test bed for the method, we find that SASI can be identified with high confidence for a distance to the supernova of up to ∼6 kpc for IceCube and and up to ∼3 kpc for a 0.4 Mt mass water Cherenkov detector. This methodology will aid the investigation of a future galactic supernova.

https://arxiv.org/abs/1910.11068
Supernova Neutrino Detection in the Deep Underground Neutrino Experiment
A. Gallego-Ros (for the DUNE Collaboration)
(Submitted on 24 Oct 2019)
The Deep Underground Neutrino Experiment (DUNE) is a dual-site experiment for long-baseline neutrino oscillation studies and for neutrino astrophysics and nucleon decay searches. The Far Detector of DUNE will consist of four 10 kt liquid argon time-projection-chambers (LAr TPC) placed in the Sanford Underground Research Facility (SURF) at 1300 km distance from the neutrino beam at Fermilab. The underground location of the Far Detector, at 4300 m.w.e. depth, is essential to be able to study rare and low-energy processes. DUNE will have a unique sensitivity to the electron neutrino flavor component of the core collapse of a massive star. With a large mass DUNE will be able to detect core collapse events in the Milky Way and its neighborhood. The present document reviews some recent progress on detection and reconstruction of supernova burst neutrinos in DUNE, including the contribution of the light detection system.

https://arxiv.org/abs/1910.03797
Predicting the next local supernova
John Middleditch (University of California, retired)
(Submitted on 9 Oct 2019 (v1), last revised 10 Oct 2019 (this version, v2))
Core collapse within blue supergiant stars, as occurred within Sk -69∘202/Supernova 1987A, is generally attributed to a merger of two electron-degenerate cores within a common envelope, with a merged mass in excess of 1.4 solar. Supernova 1987A also had two associated bright sources, one with about 8% of the H-alpha flux, and 74 milli-arc seconds distant by day 50, and another, four times fainter and 160 milli-arc seconds away in the opposite direction on day 30. Using recent advances in our understanding of pulsars, we can show that the second source was the result of the core-merger process, which can drive a relativistic jet of particles prior to the completion of the merger process, whether this proceeds to core collapse, or not. As with those resulting from core-collapse, such beams and jets are likely to produce an obvious spectral signature (e.g., in red/blue-shifted H-alpha), which can be detected in nearby galaxies. There is very likely a time interval of a few months, during which such supergiant stars, a high fraction of which will eventually undergo core collapse, can be identified. These can be carefully followed observationally to maximize the chance of observing core collapses as they happen. Such studies may eventually help in using such objects as standard candles.

https://arxiv.org/abs/1909.03151
Triangulation Pointing to Core-Collapse Supernovae with Next-Generation Neutrino Detectors
N. B. Linzer, K. Scholberg
(Submitted on 7 Sep 2019)
A core-collapse supernova releases the vast majority of the gravitational binding energy of its compact remnant in the form of neutrinos over an interval of a few tens of seconds. In the event of a core-collapse supernova within our galaxy, multiple current and future neutrino detectors would see a large burst in activity. Neutrinos escape a supernova hours before light does, so any prompt information about the supernova's direction that can be inferred via the neutrino signal will help to enable early electromagnetic observations of the supernova. While there are methods to determine the direction via intrinsic directionality of some neutrino-matter interaction channels, a complementary method which will reach maturity with the next generation of large neutrino detectors is the use of relative neutrino arrival times at different detectors around the globe. To evaluate this triangulation method for realistic detector configurations of the next few decades, we generate random supernova neutrino signals with realistic detector assumptions, and quantify the error in expected time delay between detections. We investigate a practical and robust method of estimating the time differences between burst detections, also correcting for detection efficiency bias. With this method, we determine the pointing precision of supernova neutrino triangulation as a function of supernova distance and location, detectors used, detector background level and neutrino mass ordering assumption. Under favorable conditions, the 1σ supernova search area from triangulation could be reduced to a few percent of the sky. It should be possible to implement this method with low latency under realistic conditions.

[Superluminal]

https://www.aavso.org/apps/webobs/re...um_results=200
Just looked at Betelgeuse. Seems to be getting brighter. But no supernova stellaris.

[Roger E. Moore]

Article saying Betelgeuse will brighten soon, with a detailed full-color chart for observers on getting the magnitude right, in case you are checking. Nice work!

https://arxiv.org/abs/1912.12539

Betelgeuse at the end of 2019: an historical minimum about to end
Costantino Sigismondi
(Submitted on 28 Dec 2019)

The semi-regular variable star Betelgeuse is undergoing an historical minimum of its brightness. An 8 year series of visual and V-band CCD observations started at the end of 2011 is presented and discussed. Visual methods for comparing magnitudes of angularly distant stars, and performing a differential photometry, needed for such a bright star, are also presented.

[Hornblower]

Roger, you are like a bloodhound in finding these articles, which are most welcome. AAVSO is our friend here.

Let's make sure we do not jump to premature conclusions that this current faint spell is indicative of a core collapse that is going to happen sooner rather than later. It is my understanding that when the last of the exothermic fusible stuff in the core is used up, the collapse will be sudden, running its course in a matter of seconds and blowing up the envelope in a few hours. Fluctuations such as we observe are from relatively superficial instabilities in the envelope, far removed from the core.

Don't take my remarks as gospel. As is so often the case my memories of sources are over past decades and I don't have the "Google-fu" to chase them down, even if it is possible to do so. Any contribution from others is most welcome. A reference librarian at a college or university astronomy library would be a big help.

I followed up with some browsing on stellar evolution, starting with Wiki articles. Once again, Wiki is not the last word, but they are usually pretty good on science topics such as this one. If this one is reliable, I find that evolutionary core changes short of the final catastrophic collapse will not make significant changes in the appearance of the star in at least hundreds of years. The heat is slow in working its way toward the photosphere. Thus I stand by my opinion that the recent fading is just superficial chaotic fluctuation in the rarified outer envelope, perhaps analogous to occasional episodes of extremely hot or extremely cold weather here on Earth.

[George]

Roger, you are like a bloodhound in finding these articles, which are most welcome. AAVSO is our friend here.
I followed up with some browsing on stellar evolution, starting with Wiki articles. Once again, Wiki is not the last word, but they are usually pretty good on science topics such as this one. If this one is reliable, I find that evolutionary core changes short of the final catastrophic collapse will not make significant changes in the appearance of the star in at least hundreds of years. The heat is slow in working its way toward the photosphere. Thus I stand by my opinion that the recent fading is just superficial chaotic fluctuation in the rarified outer envelope, perhaps analogous to occasional episodes of extremely hot or extremely cold weather here on Earth.

And today's APOP story. seems to support this logical view, at least no hyperbole there.

[trinitree88]

https://www.aavso.org/apps/webobs/re...um_results=200
Just looked at Betelgeuse. Seems to be getting brighter. But no supernova stellaris.

Superluminal. A nearby supernova would be spectacular, but I go with you on that source. The author puts it no later than February 2020 for the absolute minimum from his years of observations as part of AAVSO. Nice guide for doing visual magnitudes at different elevations above horizon (declination for rookies)...with corrections for atmospheric extinction. I'll bet a hot fudge sundae that it does not blow up this year, for the first taker, and will gladly pay for the sundae, and all the science to be learned if it does.
I'll up the ante a bit, if it core collapses, and produces a neutron star, the MESA code used by , Patton, Lunardini, Farmer, and Timmes, predicts an increase of neutrino flux by two orders of magnitude in the last half day approaching the final, prompt neutrino burst. At this distance from Betelgeuse, neutrino detectors, particularly those at the Spallation Neutron Source in Tennessee watching COHERENT experiments with cesium iodide doped with thallium, and by Juan Collar, in Chicago (Fermilab), should give ~ 5 hour early warning for observing for a bulletin to be sent out. That would confirm their statistics. I'l bet a second hot fudge sundae, that if it blows, and I lose my first sundae on that bet, that the early warning increase of mixed flavor neutrino fluxes (electron-type, muon-type, and tau-type) will ring detectors all over the world.
SEE:https://arxiv.org/pdf/1709.01877.pdf

pete

[Superluminal]

Superluminal. A nearby supernova would be spectacular, but I go with you on that source. The author puts it no later than February 2020 for the absolute minimum from his years of observations as part of AAVSO. Nice guide for doing visual magnitudes at different elevations above horizon (declination for rookies)...with corrections for atmospheric extinction. I'll bet a hot fudge sundae that it does not blow up this year, for the first taker, and will gladly pay for the sundae, and all the science to be learned if it does.
I'll up the ante a bit, if it core collapses, and produces a neutron star, the MESA code used by , Patton, Lunardini, Farmer, and Timmes, predicts an increase of neutrino flux by two orders of magnitude in the last half day approaching the final, prompt neutrino burst. At this distance from Betelgeuse, neutrino detectors, particularly those at the Spallation Neutron Source in Tennessee watching COHERENT experiments with cesium iodide doped with thallium, and by Juan Collar, in Chicago (Fermilab), should give ~ 5 hour early warning for observing for a bulletin to be sent out. That would confirm their statistics. I'l bet a second hot fudge sundae, that if it blows, and I lose my first sundae on that bet, that the early warning increase of mixed flavor neutrino fluxes (electron-type, muon-type, and tau-type) will ring detectors all over the world.
SEE:https://arxiv.org/pdf/1709.01877.pdf

pete

IIRC it was Kamiokandi in Japan that first detected SN1987. But they didn't know what to make of the uptick in neutrinos, until the SN was detected by visual observes several hours later.

[George]

Superluminal. A nearby supernova would be spectacular, but I go with you on that source. The author puts it no later than February 2020 for the absolute minimum from his years of observations as part of AAVSO. Nice guide for doing visual magnitudes at different elevations above horizon (declination for rookies)...with corrections for atmospheric extinction. I'll bet a hot fudge sundae that it does not blow up this year, for the first taker, and will gladly pay for the sundae, and all the science to be learned if it does.
I'll up the ante a bit, if it core collapses, and produces a neutron star, the MESA code used by , Patton, Lunardini, Farmer, and Timmes, predicts an increase of neutrino flux by two orders of magnitude in the last half day approaching the final, prompt neutrino burst. At this distance from Betelgeuse, neutrino detectors, particularly those at the Spallation Neutron Source in Tennessee watching COHERENT experiments with cesium iodide doped with thallium, and by Juan Collar, in Chicago (Fermilab), should give ~ 5 hour early warning for observing for a bulletin to be sent out. That would confirm their statistics. I'l bet a second hot fudge sundae, that if it blows, and I lose my first sundae on that bet, that the early warning increase of mixed flavor neutrino fluxes (electron-type, muon-type, and tau-type) will ring detectors all over the world.
SEE:https://arxiv.org/pdf/1709.01877.pdf

What about VY Canis Majoris? I'm starting to associate coming SN with ice cream.

Do you still think green emission from Fe should be a precursor sign?

[ngc3314]

From some links on social media lately, I was directed to a paper on late pre-SN evolution of a red supergiant. To my surprise (that is, something apparently worked out after I left grad school), the Ne-fusing phase puts out what is probably a detectable neutrino flux from the distance of Betelgeuse, which would give about a year's warning. That's probably too fast for the outer layers to undergo any structural changes, hence the usual statement that their first inking of the explosion is when the shock wave comes bursting out a few hours after core collapse. (Unless there's a GRB jet - and Betelgeuse is rare in that we're pretty sure we know its rotation axis and its not pointed at us).

I spent a couple of hours on the art of greatly-defocussed CCD photometry and got V=1.40, B=3.25 for Betelgeuse in the early hours of Dec 31 UT. Aldebaran had V=0.90, pretty close to its typical level. I would have put Betelgeuse a bit fainter with the eyeball comparing to nearby stars, maybe testifying to the subtleties of estimates across large angles of sky and differences in color.

[trinitree88]

What about VY Canis Majoris? I'm starting to associate coming SN with ice cream.

Do you still think green emission from Fe should be a precursor sign?

George. Yep. I did some reading on mixing in giants, and there are a few papers indicating that earlier models of turbulence and confinement, particularly in stars that pulsate underestimate the ability of the interior isotopic gases to mix during the pulsation phases. So, I 'll risk that some clever observer, can figure out the possible spectral lines to search for to indicate iron, highly ionized, create a filter to search a very narrow Doppler shifted band, and pick up iron as it accumulates. My older supernovae model readings had indicated the time scale for accumulaton initiation till collapse is about 10 days to 2 weeks. I believe I suggested it as a science fair project at my talk at Norwich College many moons ago...circa 1997. And yep, I will owe some ice cream sundaes if it is not detected. lol.....pete

I still owe Grey...I sent him a note, to pay up, but I think he missed it. I will pay my bets, Indian food for Antoniseb....done.lol

[Grey]

I still owe Grey...I sent him a note, to pay up, but I think he missed it. I will pay my bets, Indian food for Antoniseb....done.lol

I did miss that. Obviously, I'm not paying close enough attention.

[antoniseb]

... I will pay my bets, Indian food for Antoniseb....done.lol

It will be nice to see you again, food or no food!

[Superluminal]

http://www.astronomerstelegram.org/?read=13410
Get out the smelling salts. Betelgeuse is still feeling faint.

[Superluminal]

http://www.astronomerstelegram.org/?read=13410
Get out the smelling salts. Betelgeuse is still feeling faint.

[Jens]

IIRC it was Kamiokandi in Japan that first detected SN1987. But they didn't know what to make of the uptick in neutrinos, until the SN was detected by visual observes several hours later.

I just wanted to mention that it is Kamiokande, not Kamiokandi, though I think it's natural to spell it that way in English, since English speakers would tend to pronounce it (incorrectly) with an "ee" sound rather than an "eh" sound, as in other Japanese words like "karaoke", which I think English speakers tend to pronounce as "kareeokee."

ETA: Actually, I was lucky enough to have the chance to get a tour of the Kamiokande experiment a few years ago. It's pretty cool.

[Strange]

I just wanted to mention that it is Kamiokande, not Kamiokandi, though I think it's natural to spell it that way in English, since English speakers would tend to pronounce it (incorrectly) with an "ee" sound rather than an "eh" sound, as in other Japanese words like "karaoke", which I think English speakers tend to pronounce as "kareeokee."

And doesn't the NDE at the end stand for Neutrino Detector Experiment (or something) based at Kamioka?

To keep things on topic, here is a really good article about what will happen, and what it will look like, when Beetlejuice goes supernova: https://www.forbes.com/sites/startsw.../#5154ffdf43a2