Betelgeuse dimmer

[Nigella Bryant]

 

Above: Betelgeuse is lopsided, according to this newly-released image from the Very Large Telescope in the Atacama Desert of Chile. Credit: ESO/M. Montargès et al

Edited February 14, 2020 by Nigella Bryant

[Scooot]

9 minutes ago, Nigella Bryant said:

 

Above: Betelgeuse is lopsided, according to this newly-released image from the Very Large Telescope in the Atacama Desert of Chile. Credit: ESO/M. Montargès et al

I wondered why & found a bit of info about it.

https://arstechnica.com/science/2020/02/new-image-shows-betelgeuse-isnt-dimming-evenly/

[Sunshine]

That star is up to some strange shenanigans, lopsided, i wasn't aware stars could develop enormous appendages .

[Nigella Bryant]

3 minutes ago, Sunshine said:

That star is up to some strange shenanigans, lopsided, i wasn't aware stars could develop enormous appendages .

Yep, stars are dynamic things. Gravity and nuclear fusion plays it's part in an ever changing battle to keep equalibrium. Hence bulging in the case of betelgeuse because of it's size and ageing process of the red giant's. That's my take on it anyway, I'm no physicist, lol. 

[Aramcheck]

Apparently Betelgeuse comprises of three stars...
(Sorry it's not a good scan)

[Nigella Bryant]

11 minutes ago, Aramcheck said:

Apparently Betelgeuse comprises of three stars...
(Sorry it's not a good scan)

How old is that information, I can't find anything recent to suggest the above, only that once around 100,000 yrs ago it may have expanded and swallowed a solar mass star as a binary system because of the current fast rotation period. 

[Aramcheck]

14 minutes ago, Nigella Bryant said:

How old is that information

From "Introductory Astronomy & Astrophysics" 4th edition - Zeilik+Gregory - (p. 284) - I think published 1998 but Fig. refers to 1982/3.

[Islander]

From Wikipedia...

Two spectroscopic companions have been proposed to the red supergiant star. Analysis of polarization data from 1968 through 1983 indicated a close companion with a periodic orbit of about 2.1 years. Using speckle interferometry, the team concluded that the closer of the two companions was located at 0.06″±0.01″ (≈9 AU) from the main star with a position angle of 273 degrees, an orbit that would potentially place it within the star's chromosphere. The more distant companion was estimated at 0.51″±0.01″ (≈77 AU) with a position angle of 278 degrees.^[69][70] Further studies have found no evidence for these companions or have actively refuted their existence,^[71] but the possibility of a close companion contributing to the overall flux has never been fully ruled out.^[72] High-resolution interferometry of Betelgeuse and its vicinity, far beyond the technology of the 1980s and '90s, have not detected any companions.^[16][73]

[Marvin Jenkins]

6 hours ago, Islander said:

From Wikipedia...

Two spectroscopic companions have been proposed to the red supergiant star. Analysis of polarization data from 1968 through 1983 indicated a close companion with a periodic orbit of about 2.1 years. Using speckle interferometry, the team concluded that the closer of the two companions was located at 0.06″±0.01″ (≈9 AU) from the main star with a position angle of 273 degrees, an orbit that would potentially place it within the star's chromosphere. The more distant companion was estimated at 0.51″±0.01″ (≈77 AU) with a position angle of 278 degrees.^[69][70] Further studies have found no evidence for these companions or have actively refuted their existence,^[71] but the possibility of a close companion contributing to the overall flux has never been fully ruled out.^[72] High-resolution interferometry of Betelgeuse and its vicinity, far beyond the technology of the 1980s and '90s, have not detected any companions.^[16][73]

Now I am going to throw this out there... it seems there was a companion. Now one cannot be be found. Betelgeuse has indigestion and is bloated like a python!

Not scientific I know, but what a gutsy pig. Rennes anyone?

Marvin

[verreli]

Looks like the dimming period has ended and Betelgeuse is in the early stages of recovery?

[PeterW]

... was thinking that last night..... only time will tell.

 

peter

[John]

It's hardly blazing tonight but no dimmer either. The fight back begins !

[Marvin Jenkins]

Betelgeuse might be brighter as per my Feb 14th post. My wife said I was so romantic. Only just realized that was Valentine’s Day. Oops.😳

Marv

[Nigella Bryant]

All indications is that Betelgeuses decline in magnitude has bottomed out and is beginning to brighten again.  At least we got to observe a deep decline in our life time, well at least in my life time. So pleased I witnessed this and our old friend will continue to shine in our autumn and winter skies.

[Whirlwind]

On 15/02/2020 at 20:42, Marvin Jenkins said:

Now I am going to throw this out there... it seems there was a companion. Now one cannot be be found. Betelgeuse has indigestion and is bloated like a python!

Not scientific I know, but what a gutsy pig. Rennes anyone?

Marvin

It is known that stars in in the RGB and AGB phases can expand and envelope a secondary star.  The evidence for these systems comes from White Dwarfs with very short period companions that couldn't have arisen from a formation mechanism.  Although no planets have (yet) been shown to survive such a mechanism, Brown Dwarfs can.  One of the shortest known such systems has a period of about 68 minutes (https://academic.oup.com/mnras/article/476/1/1405/4832497).  There are also eclipsing examples (https://academic.oup.com/mnras/article/471/1/976/3892366).  Such systems are known as Post Common Envelope Binaries (PCEB).

The general theory is that the companion is swallowed during the RGB and AGB stages and then spirals inwards whilst imparting angular momentum into the shell of the star which eventually ejects the shell of the star.  It is thought that sub-dwarf stars are post AGB/RGB stars where this has happened but have not yet shrunk down to White Dwarfs. About 50% of the sub-dwarfs show close companions.  It is speculated that the other 50% could have their shells ejected because of massive planets being swallowed but are ultimately destroyed.

As such it is possible that Betelgeuse could have a companion.  Which in itself would be fascinating as these stages are very short lived (in astronomical terms) and difficult to identify.  What makes the above plots questionable is that this stage generally very rapidly makes orbits circular rather than elliptical and hence to see in a rare event in a very rare circumstance is unlikely (but not impossible).  It does potentially explain Betelgeuse's rapid rotation though.  We can all do the experiment on a spinning chair to show how we spin faster if the mass is closer to the centre of rotation.  As such as a star expands its rotation should slow.  A fast rotation at this stage would imply the progenitor star was rotating unusually rapidly or that something is spinning it up.  That could be a common envelope companion.  The disadvantage is that if there are companion(s) then our estimates of Betelgeuse's mass could be wrong and it may never go supernova.

 

[PeterW]

Looks like it’s on the way back up... AAVSO light curve. Well one to tell the kids and show all your friends before normal service is resumed.

Peter

[Stub Mandrel]

Still looked really puny last night. I was surprised my companions had not heard the news!

[JeremyS]

Indeed, fade seems to have halted and now brightening: http://www.astronomerstelegram.org/?read=13512&fbclid=IwAR0IKE3X1JGn0Qxx3grPnWaeLF7e7IWFdqioStMaX9qeKgkIMTyGStqkJHo

[tooth_dr]

Here is a shot I took last night compared with one from last March

 

 

[JeremyS]

There is an excellent article by Dr. Mark Kidger on "Supernova Betelgeuse?" on page 10 of the current BAA Variable Star Section Circular. It summarises our current understanding of the star and its current fade: well worth a read!

The star has been gradually brightening since mid Feb and is currently magnitude 1.4. 

[Walshie79]

Back to first magnitude now. About equal with Aldebaran and Pollux, clearly brighter than Bellatrix, still fainter than Procyon. Estimate 1.2, at its faintest I had it around 1.9

[InfiniteMonkey]

Regardless of whether Betelgeuse goes into a supernovae in our lifetime or in 100 000 years, it´s astronomicly speaking a blink of an eye. So i thought it´s time for me to make a musical tribute for Betelgeuse!

https://www.youtube.com/watch?v=rJ-m_2CSN90

[Mick H]

Could it be that the air is now getting cleaner with this lockdown, so it appears a little brighter?

As you can see, I'm no Scientist. 😳

[Stub Mandrel]

On 20/04/2020 at 20:18, Mick H said:

Could it be that the air is now getting cleaner with this lockdown, so it appears a little brighter?

As you can see, I'm no Scientist. 😳

Apparent magnitude varies a lot with things like elevation and sky transparency anyway, so magnitude measurements are made by comparing to reference stars which rules out changes in 'sky quality' affecting the measurements.

[Geoff Barnes]

Always nice and high in the sky here, but Betelgeuse was definitely a lot brighter a couple of nights ago than it was when it was at its dimmest. Almost back to its best I would venture to say.