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Betelgeuse is faint (for it)

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#26 smithrrlyr

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Posted 07 December 2019 - 01:11 AM

Not only did Betelgeuse appear faint tonight (around visual mag +1.0 or a bit fainter), but it appeared redder than usual to my eye.  Of course, it could be that its fainter magnitude makes its reddish color easier to discern.


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#27 goodricke1

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Posted 08 December 2019 - 07:13 AM

Betelgeuse dimmed to mag 1.12 on December 7, its faintest in modern times - 

 

http://www.astronome...org/?read=13337


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#28 Organic Astrochemist

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Posted 11 December 2019 - 01:03 AM

Here's a quick low resolution spectrum of Alpha Orionis taken after the wife and kids went to bed. A humble spectrum of a great star. TiO absorptions are in red -- no doubt that TiO is contributing to the dimming of the star.

alpha ori with TiO.png


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#29 Aquarellia

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Posted 20 December 2019 - 03:28 AM

The show is not finish !

 

Here the AAVSO curve for the 75 last days.

 

aavso-7.jpg

 

Clear sky to you all

Michel

 

 


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#30 Waddensky

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Posted 20 December 2019 - 05:47 AM

Betelgeuse dimmed to mag 1.12 on December 7, its faintest in modern times - 

 

http://www.astronome...org/?read=13337

Seems that the url has changed: http://www.astronome...org/?read=13341

 

I observed Betelgeuse a few nights ago and the relative dimness is easy to see. To me it seems like it's approaching the brightness of Bellatrix, although it's difficult to compare stars with such difference in colour. In any case, Betelgeuse is much, much dimmer than Aldebaran. Very interesting!


Edited by Waddensky, 20 December 2019 - 05:48 AM.


#31 goodricke1

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Posted 20 December 2019 - 06:08 AM

Seems that the url has changed: http://www.astronome...org/?read=13341

 

They explain the reason why at the end. Thanks for spotting that.


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#32 KMA

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Posted 20 December 2019 - 06:49 AM

Here is AAVSO LCG1
(obs depicted by crosses are NOT mine)
where over 100 contributors are listed.
Really impressive.
best regards
KMA

Attached Thumbnails

  • Betelgeuse.png

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#33 Dave Mitsky

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Posted 23 December 2019 - 12:33 AM

Not only did Betelgeuse appear faint tonight (around visual mag +1.0 or a bit fainter), but it appeared redder than usual to my eye.  Of course, it could be that its fainter magnitude makes its reddish color easier to discern.

The change in magnitude and color has been quite noticeable of late.


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#34 Aquarellia

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Posted 23 December 2019 - 12:49 AM

In spaceweather today:

https://www.spacewea...th=12&year=2019

Michel


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#35 Dave Mitsky

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Posted 23 December 2019 - 11:06 AM

https://www.iflscien...nAauZAL2msjJRqA


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#36 skysurfer

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Posted 24 December 2019 - 01:33 PM

I just saw it, and it appears barely brighter than Bellatrix.

 

This is how Betelgeuse should look on top of Cerro Paranal (the 39m ESO ELT) when it goed BOOM.

 

betelgeuse1.jpg


Edited by skysurfer, 24 December 2019 - 01:49 PM.

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#37 kdenny2

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Posted 24 December 2019 - 05:24 PM

This is some pretty dramatic dimming for just a month. 

 

https://www.facebook...33936700807404/

 

I observed Betelgeuse last night around 02:00 UTC and I'd estimate its visual magnitude to be ~+1.2, brighter than Bellatrix but only just so.


Edited by kdenny2, 24 December 2019 - 05:26 PM.

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#38 John Fitzgerald

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Posted 24 December 2019 - 10:47 PM

I estimated Betelgeuse tonight 12/24/19 to be very slightly fainter than Pollux, at 1.14, so about 1.2 to 1.25.  Definitely brighter than Bellatrix.


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#39 aa6ww

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Posted 26 December 2019 - 01:21 PM

its showing up in lots of space articles now:

 

https://www.national...bout-supernova/

 

Still its cool to see it dim as much as it is. Im waiting for a clear night to catch it.

 

...Ralph


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#40 Thomas Marshall

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Posted 26 December 2019 - 06:22 PM

When I first noticed this, I wrote it off to low altitude, or perhaps faint haze causing dim view, - it didn't occur to me that it could actually change so much, - so soon, - even though Rigel still was plenty bright nearby, haze or not. Wonder what will happen?



#41 smithrrlyr

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Posted 27 December 2019 - 09:51 AM

It is likely that this is just an extreme of Betelgeuse's normal variability, but it will be fun to follow it.  Dips to near 0.9 mag are not that uncommon for the star, as evident in the light curves that have been posted.  The current dip is larger, but some distant red supergiants visible in telescopes show an even greater degree of variability without proceeding to immediate explosion.


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#42 John Fitzgerald

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Posted 27 December 2019 - 09:59 AM

It is likely that this is just an extreme of Betelgeuse's normal variability, but it will be fun to follow it.  Dips to near 0.9 mag are not that uncommon for the star, as evident in the light curves that have been posted.  The current dip is larger, but some distant red supergiants visible in telescopes show an even greater degree of variability without proceeding to immediate explosion.

I wonder if there is a possibility it is becoming a Mira type variable?   But, that extreme variability may be a different mechanism entirely.

 

It seems it would have to shed a lot of mass first, if the current mass estimates are accurate.

 

https://www.aavso.org/vsots_alphaori


Edited by John Fitzgerald, 27 December 2019 - 10:15 AM.


#43 Waddensky

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Posted 27 December 2019 - 10:20 AM

It is likely that this is just an extreme of Betelgeuse's normal variability, but it will be fun to follow it. Dips to near 0.9 mag are not that uncommon for the star, as evident in the light curves that have been posted. The current dip is larger, but some distant red supergiants visible in telescopes show an even greater degree of variability without proceeding to immediate explosion.

Agreed. The chances of Betelgeuse going supernova during our lifetime is incredibly small, even with the most 'optimistic' scenarios.

It is very interesting however to be able to observe this process on a distant star and to wonder what's going on over there.
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#44 kdenny2

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Posted 27 December 2019 - 01:03 PM

Well, supernova or not, this is a great introduction for many into variable star observations! Seeing such a bright and culturally significant star do something like this is pretty incredible to watch. 


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#45 smithrrlyr

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Posted 27 December 2019 - 01:04 PM

I wonder if there is a possibility it is becoming a Mira type variable?   But, that extreme variability may be a different mechanism entirely.

 

It seems it would have to shed a lot of mass first, if the current mass estimates are accurate.

 

https://www.aavso.org/vsots_alphaori

The typical Mira star is indeed a red giant with a mass near 1 solar mass, and therefore much smaller in mass than Betelgeuse, as you noted.  However, some red supergiants do show periodic variations in brightness that, like the Mira stars, can reach several magnitudes in V.  S Persei is a nice example of a red supergiant with a circa 800 day main period and a visual amplitude that can reach 5 magnitudes or so.  Its variability can sometimes be rather irregular and it is a fun star to follow with a telescope.


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#46 John Fitzgerald

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Posted 27 December 2019 - 01:41 PM

By next fall, Betelgeuse will likely be brighter than magnitude 0.6 or so.  See the light curves from 1941-1942.


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#47 Forward Scatter

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Posted 28 December 2019 - 11:13 AM

AstroImageJ (free) has a large number of variable star photmetry tutorials on their Youtube channel:

 

https://www.youtube....9e6bB-OLvFN4KLo

 

Coupled with even a smartphone to do afocal imaging off an alt/azi mount, this could offer weeks of fun for us!


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#48 k.s.min

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Posted 29 December 2019 - 09:42 AM

AstroImageJ (free) has a large number of variable star photmetry tutorials on their Youtube channel:

 

https://www.youtube....9e6bB-OLvFN4KLo

 

Coupled with even a smartphone to do afocal imaging off an alt/azi mount, this could offer weeks of fun for us!

Thank  you  for  this  information.  

lnteresting.  



#49 kdenny2

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Posted 29 December 2019 - 03:08 PM

I haven't observed the star as of late but AAVSO observations indicate Betelgeuse has continued to dim to about ~+1.4. At this rate, it could be as dim as Bellatrix in a week or so.


Edited by kdenny2, 29 December 2019 - 03:14 PM.

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#50 robin_astro

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Posted 31 December 2019 - 11:51 AM

A carefully flux calibrated ALPY 600 spectrum from last night (using two reference stars and repeat spectra) shows a small increase in depth of the molecular bands compared with the MILES reference spectrum taken when the brightness was more typical.  Considering the current brightness is probably around half what it was then the changes in the spectrum are rather subtle. The spectrum has been added to the BAA database.

 

Cheers

Robin

 

betelgeuse_telrem_20191230_949_Leadbeater.png


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