Betelgeuse Fainting

[Hornblower]

I just now looked and it definitely appears to be back to its old self. I estimated about 0.9 and then looked at the latest AAVSO plot, and we are in good agreement.

https://www.aavso.org/lcg/plot?auid=...&bband=on&v=on

So much for the media horsefeathers about speculation that it was about to blow.

[Superluminal]

Betelgeuse seems to be rising at the same rate that it fainted.
If this will remain the maximum rate of increasing luminosity, it is reliable to expect Betelgeuse reaching a maximum visual magnitude of 0.4 at the end the present rising phase.
http://www.astronomerstelegram.org/?read=13601
I was kinda hoping that if we didn't see a Supernova, maybe we would get a big bounce as it came out of minimum.

[Roger E. Moore]

Gonna go outside and look for Orion tonight. See if I can get telescope fixed this week, too. Also...

[Trebuchet]

It was just sheltering in place before it was fashionable.

[Superluminal]

Antoniseb suggested using the Curiosity rovers camera to monitor Betelgeuse during the period when it's too close to the sun for observation. In my bored self quarantined state, I sent e mails to Edward Guinnen and several NASA mission sights, suggesting such a thing. I just got a response from Edward Guinnen, he's talked to the Curiosity camera teams PI. They're going to investigate to see if they can do it.
Not sure now if they can do it. Perseverance launches in July, which means Earth and Mars will be nearly alligned on the same side of the sun. As viewed from Mars, Betelgeuse may be too close to the sun to see. We'll see.

[Hornblower]

Check out the latest from AAVSO. It appears to be about 0.5 and rising steadily.
https://www.aavso.org/lcg/plot?auid=...&bband=on&v=on

[Roger E. Moore]

Antoniseb suggested using the Curiosity rovers camera to monitor Betelgeuse during the period when it's too close to the sun for observation. In my bored self quarantined state, I sent e mails to Edward Guinnen and several NASA mission sights, suggesting such a thing. I just got a response from Edward Guinnen, he's talked to the Curiosity camera teams PI. They're going to investigate to see if they can do it. Not sure now if they can do it. Perseverance launches in July, which means Earth and Mars will be nearly alligned on the same side of the sun. As viewed from Mars, Betelgeuse may be too close to the sun to see. We'll see.

Did not see this before. YAY INTERNET go go go!

[Superluminal]

Maybe the brightening will be more interesting than the fainting. The star contracted more than normal, now it'll make a big bounce.

[CJSF]

Maybe the brightening will be more interesting than the fainting. The star contracted more than normal, now it'll make a big bounce.

But that's not what seems to be responsible. It's most likely huge quantities of dust, based on theory and observation.

https://lowell.edu/dimming-betelgeus...w-study-shows/

CJSF

[Superluminal]

That's one hypothesis. Also, the brightening began in February, concomitant with the end of one of Betelgeuses natural cycles. I just checked on it and it's very nearly as bright as Capella. That makes this year one of Betelgeuses faintest and brightest apparitions ever.

[Roger E. Moore]

A question was mentioned here before about Betelgeuse being the product of a stellar merger. A new paper on the topic, released to arXiv just now.

https://arxiv.org/abs/2005.04172
[Submitted on 8 May 2020]
Is Betelgeuse the Outcome of a Past Merger?
E. Chatzopoulos, Juhan Frank, Dominic C. Marcello, Geoffrey C. Clayton
We explore the possibility that the star alpha Orionis (Betelgeuse) is the outcome of a merger that occurred in a low mass ratio (q = M2/M1 = 0.07 - 0.25) binary 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 their surface properties 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 typically with radius ~200 - 300 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 argue that the best scenario that can explain both the fast rotation of Betelgeuse and its observed large space velocity is one where a binary was dynamically ejected by its parent cluster a few million years ago and then subsequently merged. An alternative scenario in which the progenitor of Betelgeuse was spun up by accretion in a binary and released by the supernova explosion of the companion requires a finely tuned set of conditions but cannot be ruled out.

[Roger E. Moore]

Betelgeuse is not brightening in the same way it dimmed.

https://arxiv.org/abs/2005.05215
Differential Speckle Polarimetry of Betelgeuse in 2019-2020: the rise is different from the fall
Boris Safonov, Alexandr Dodin, Marina Burlak, Maria Goliguzova, Anna Fedoteva, Sergei Zheltoukhov, Sergei Lamzin, Ivan Strakhov, Olga Voziakova
[Submitted on 11 May 2020]
Recently published episodic spectral (Levesque and Massey, 2020) and high angular resolution (Montarges et al, 2020) observations of Betelgeuse suggest that the deep minimum of 2019-2020 was caused by an enhanced dust abundance in the stellar atmosphere. Detailed monitoring of such events may prove useful for constructing consistent physical models of mass loss by evolved stars. For such observations it is fundamentally important to employ methods resolving an inhomogeneous stellar atmosphere. We present the differential speckle polarimetric observations of Betelgeuse at 2.5-m telescope of Caucasian Mountain Observatory of SAI MSU covering the period of 2019-2020 minimum. The observations were secured on 17 dates at wavelengths 465, 550, 625 and 880 nm. The circumstellar reflection nebula with the angular size of ≈0.1′′ was detected for all the dates and at all wavelengths. The morphology of the nebula changed significantly over the observational period. Net polarized brightness of the envelope remained constant until February 2020, while the stellar V-band flux decreased 2.5 times. Starting from mid-February 2020, polarized flux of the envelope rose 2.1 times, at the same time the star returned to the pre-minimum state of October 2019. Basing on these data and our low resolution spectrum obtained on 2020-04-06, we confirm a conclusion that the minimum is caused by the formation of a dust cloud located on the line of sight. A quantitative characterisation of this cloud will be possible when the data on its thermal radiation are employed.

[Roger E. Moore]

Betelgeuse photographs in living color!

https://www.syfy.com/syfywire/b-e-t-e-l-g-e-u-s-e

[publiusr]

Now, I seem to remember that some thought that the possible planet 9 would be in the general direction of Orion—but closer to the “belt”

Maybe the photographer in the article could take a look

[CJSF]

Now, I seem to remember that some thought that the possible planet 9 would be in the general direction of Orion—but closer to the “belt”

Maybe the photographer in the article could take a look

Planet 9 would be so far out there and so faint that it will take a specific and targeted search process (or something that also happens to catch majorly faint planetary objects by serendipity) to find it. Just photographing the vicinity of Orion is not going to find it.

CJSF

[publiusr]

We assume that it was dust from the star itself—I wonder if something else might have occulted it

[Superluminal]

The magnitude estimate on AAVSO for Betelgeuse is from May 12. Magnitude estimated to be 0.55, just a bit brighter than Betelgeuses average of 0.7. It appears this maybe the last observation until it emerges from morning twilight in a couple of months.

[Roger E. Moore]

Two new papers out today on Betelgeuse that you may find of interest.

https://arxiv.org/abs/2006.15403
[Submitted on 27 Jun 2020]
Betelgeuse -- A Century and More of Variation
Christopher Lloyd
The mean light curve of Betelgeuse is constructed from the visual data in BAA VSS and AAVSO archives. Period analysis reveals clusters of periods around 2000 and 400 days but these are swamped by the long-term trends. No identifiable periods emerge but the feature near 400 days is the most persistent and survives even when the range of variation is low. Herschel's data from 1836-40 and early data from the BAA VSS around 1900 show a range of V 0 -- 1, so the star was brighter and more active than recently. Historically it shows a wide range of behaviour.


https://arxiv.org/abs/2006.16086
[Submitted on 29 Jun 2020]
Early Warning Signals Indicate a Critical Transition in Betelgeuse
Sandip V. George, Sneha Kachhara, Ranjeev Misra, G. Ambika
Critical transitions occur in complex dynamical systems, when the system dynamics undergoes a regime shift. These can often occur with little change in the mean amplitude of system response prior to the actual time of transition. The recent dimming and brightening event in Betelgeuse occurred as a sudden shift in the brightness and has been the subject of much debate. Internal changes or an external dust cloud have been suggested as reasons for this change in variability. We examine whether the dimming and brightening event of 2019-20 could be due to a critical transition in the pulsation dynamics of Betelgeuse, by studying the characteristics of the light curve prior to transition. We calculate the quantifiers hypothesised to rise prior to a critical transition for the light curve of Betelgeuse upto the dimming event of 2019-20. These include the autocorrelation at lag-1, variance and the spectral coefficient calculated from detrended fluctuation analysis (DFA), apart from two measures that quantify the recurrence properties of the light curve. Significant rises are confirmed using the Mann-Kendall trend test. We see a significant increase in all quantifiers (p < 0.05) prior to the dimming event of 2019-20. This suggests that the event was a critical transition related to the underlying nonlinear dynamics of the star. Together with results that suggests minimal change in Teff and infra-red flux, a critical transition in the pulsation dynamics could be a possible reason for the unprecedented dimming of Betelgeuse. The rise in the studied quantifiers prior to the dimming event, supports this possibility.

[Superluminal]

Latest hypothesis for Betelgeuse fainting.
https://phys.org/news/2020-06-giant-...e-dimming.html

[Superluminal]

Well, they are keeping an eye on Betelgeuse with the Stereo A spacecraft. It's still acting a bit peculiar and is starting to faint again.
http://www.astronomerstelegram.org/?read=13901

[Superluminal]

Results of a Hubble study of Betelgeuse.
https://hubblesite.org/contents/news...0/news-2020-44

[CJSF]

Here's the BA's report on the Hubble results:
https://www.syfy.com/syfywire/smokin...red-supergiant

CJSF

[Superluminal]

https://www.aavso.org/apps/webobs/re...um_results=200
Looks as if Betelgeuse has settled down to around .6-.7 magnitude. Close to its average.

[CJSF]

The Twitter Betelbot has been reporting a slight but persistent dimming over the last weeks. As of yesterday I think it was ~85% of its average brightness.

CJSF

[Superluminal]

I checked Betelgeuse last night. It appears just slightly brighter than .8 mag. Aldebaran.

[CJSF]

Betelbot reporting 79% of average brightness.

https://twitter.com/betelbot/status/1325153188199059456

CJSF

[Superluminal]

AAVSO is showing Betelgeuse at around 0.7. Which agrees with my observations of just slightly brighter than 0.86 mag. Aldebaran.
https://www.aavso.org/apps/webobs/re...um_results=200

[swampyankee]

Since Betelgeuse was "fainting," perhaps its recovery from the swoon is due to cosmic smelling salts?


I don't know, offhand, how far back quantitative (vs qualitative) data about Betelgeuse's brightness goes (I'd guess less than 150 years or so), but it would be interesting to know whether this is a novel behavior or something that's recurring.

As to whether Betelgeuse will explode soon or not, in stellar terms wouldn't "soon" be sometime in the next 100,000 years or so, as opposed to, say, a human lifetime or the shorter lifetime of a working astrophysicist.

[Superluminal]

Since Betelgeuse was "fainting," perhaps its recovery from the swoon is due to cosmic smelling salts?


I don't know, offhand, how far back quantitative (vs qualitative) data about Betelgeuse's brightness goes (I'd guess less than 150 years or so), but it would be interesting to know whether this is a novel behavior or something that's recurring.

As to whether Betelgeuse will explode soon or not, in stellar terms wouldn't "soon" be sometime in the next 100,000 years or so, as opposed to, say, a human lifetime or the shorter lifetime of a working astrophysicist.

This current fainting is the lowest since record keeping began. The first entry in the AAVSO catalog for Betelgeuse is December 10th 1893, 0.6 magnitude. According to "Burnham's Celestial Handbook," the variations of Betelgeuse were probably first noticed by Sir John Hershel in 1836.
And yes, 100,000 years is like next week, astrnomacly speaking.

[CJSF]

The last few Betelbot entries I saw on Twitter had a range of brightness from 79 to 85% of the running average, non linear.

CJSF