Betelgeuse

Here's the place for any sights you wish to remark on

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stella
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Re: Betelgeuse

Post by stella »

Yes Bob, I do.

RMSteele
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Re: Betelgeuse

Post by RMSteele »

The question is ambiguous
I know,
Whether our stellar Betelgeuse
Should glow
Brighter or fainter, that's your cue,
Just so
You can tell me, "Yes Bob, I do."
:P

stella
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Re: Betelgeuse

Post by stella »

Comparing stars both red and blue,
Is a very hard thing to do,
I've looked for rhyme,
And taken my time,
But 'Purkinje Effect' ; I haven't a clue.

RMSteele
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Re: Betelgeuse

Post by RMSteele »

Staring too hard at Purkinje
Could seriously unhinge ye,
So start with one wee Pogson step,
And try it out on Delta Cep,
A star by far more yellowy.

RMSteele
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Re: Betelgeuse

Post by RMSteele »

2020 March 03, 2115 UT. New Farnley, West Yorkshire, UK. Unaided eye, artificial light sources shielded, Moon close to the field shielded. Variable well seen at a reasonable altitude.
Light estimate: Gamma (Bellatrix, Vmag 1.64) +2 (Pogson Step Method). Deduced Vmag Betelgeuse is 1.44.

RMSteele
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Re: Betelgeuse

Post by RMSteele »

Betelgeuse seems to be well on the mend. I estimate it tonight at Vmag 1.14, or possibly a little brighter, see below.
2020 March 20, 20.20 UT. Unaided eye, sky dark but affected by artificial illumination - street lamps shielded by my arm. Light estimate: gamma (Bellatrix, Vmag 1.64) +5 (Pogson Step method). Deduced Vmag Betelgeuse is 1.14 HOWEVER, this is an estimate at the limit of the Pogson Step method and it is easy to get it wrong. I suspect that Betelgeuse might even be a little brighter than that, maybe around Vmag 1.0. I'd like to see some other recent estimates.
Unambiguously, Bob

RMSteele
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Re: Betelgeuse

Post by RMSteele »

While outside giving health workers a clap, I estimated Betelgeuse tonight at about Vmag 0.9.
2020 March 26, 20.00 UT. Unaided eye, sky dark but affected by artificial illumination - street lamps shielded by my arm. Light estimate: Procyon (0.34) 2 (V) 3 Bellatrix (1.64) fractional step method. Deduced Vmag Betelgeuse is 0.86.
Kind thoughts, Bob

Cliff
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Re: Betelgeuse

Post by Cliff »

Christmas 2019, David Frydman mentioned Betelgeuse's unusual variability on the Forum. Others including Bob, BrianL, Nigel & Stella have shown observing interest. I've been a sluggish armchair astronomer, reading in Patrick Moore's 1997 book "Brilliant Stars"; Betelgeuse's slight variability was noted by John Herschel in 1836. Patrick observed variations of 0.0 to 0.9, official catalogues calling it a semi-regular variable with 5.75 year period.
BBC Science Focus (March 2020) "Betelgeuse; is this super-giant about to explode?" says - in Jan & Feb 2020 it reached a record low - 40% its usual brightness, one day "soon" going Super-nova. Currently its variable period is about 14 months. Although it might BANG tomorrow we may be waiting 100,000 years.
Best of luck from Cliff

nigeljoslin
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Re: Betelgeuse

Post by nigeljoslin »

It was certainly looking healthy last night, Cliff, lovely through my 9x63 binoculars.

I always imagined that red giants would cool fairly uniformly, but I assume what is happening here is that the star cools a little and then collapses inward a little, releasing more energy, which stokes its fire for a while.

Interesting to see.

Best wishes,

Nigel
Skywatcher 350P f4.65, Skywatcher StarTravel 102 f5, Adler Optik 9x63 binoculars

Cliff
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Re: Betelgeuse

Post by Cliff »

Nigel
I'm no expert on variable stars (or other aspects of astronomy for that matter). Although ages ago, I did do a sort of self training trial course for several months before opting to look at planets & DSOs. Back in those old days I doubt Betelgeuse would have attracted my interest because of its considerable brightness - but limited variation & colour complication problems.
I gather even now not everyone thinks Betelgeuse's recent considerable variations in apparent brightness relate to its likelihood of going BANG fairly soon, but might be caused by the star drifting through clouds of gas, dust or even some stuff splurted out by the star itself.
Regards from Cliff

nigeljoslin
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Re: Betelgeuse

Post by nigeljoslin »

Thanks, Cliff. I hadn't considered the possibility of the star being partly obscured by gas clouds.

Best wishes,

Nigel
Skywatcher 350P f4.65, Skywatcher StarTravel 102 f5, Adler Optik 9x63 binoculars

Cliff
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Re: Betelgeuse

Post by Cliff »

Nigel
That's OK but it's only gen I read - and there's more !
American astronomer, Fred Schaaf's 2008 book "The Brightest Stars" provides interesting gen.
After mentioning John Herschel as possibly first to note Betelgeuse's brightness variations, Schaaf goes on that changes were quite dramatic 1836 to 1840, more so 1849 to 1852; bright again 1894.
He says, Robert Burnham Jnr, reckons Betelgeuse had high maxima brightness, 1925, 1930, 1933, 1942 & 1947, but in the decade 1957 to 1967, only slight variations.
AAVSO graphs showed Betelgeuse probably reached mag 0.2 in 1933 & 1942.
Joseph Ashbrook studied Betelgeuse 1937 to 1975 estimating its extreme range -0.1 to +1.1. In February 1957 he noted brightening by 0.4, then dimming back again in two weeks.
Apparently Betelgeuse was noted for unpredictable brightness fluctuations over approximately regular periods. The main period being about 5.7 years with short superimposed periods of between 150 & 300 days.
Best wishes from Cliff

nigeljoslin
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Re: Betelgeuse

Post by nigeljoslin »

Thanks for the info, Cliff; it is certainly unpredictable!

I looked for a visual depiction. The only longer term one I could find was the one below, over a period from 1988 to 2002. Interesting to see!

https://en.wikipedia.org/wiki/Betelgeus ... lgeuse.png
Skywatcher 350P f4.65, Skywatcher StarTravel 102 f5, Adler Optik 9x63 binoculars

RMSteele
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Re: Betelgeuse

Post by RMSteele »

2020 April 11, 20.55 UT. Unaided eye, sky dark but affected by artificial illumination. Light estimate: Procyon (0.34)-4, Pogson step method. Deduced Vmag Betelgeuse is 0.74.
Kind thoughts, Bob

RMSteele
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Re: Betelgeuse

Post by RMSteele »

Astronomers say the dimming was caused by giant star spots and not by dust. See article in BBC news - science and environment.
Bob

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