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16 minutes ago, Nigella Bryant said:

This last dimming cycle is quite unusual as the star is at record low brightness, and this dimming is significant enough to be seen by the naked eye. The latest data has the magnitude of the star at 1.5, which is 0.2 magnitudes dimmer than the previous known record of 1.3 magnitudes in 1927 and 1941.

Thanks for that, I was bang on then ūüĎć

Where did you get the info from, out of interest.

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10 minutes ago, Stu said:

Thanks for that, I was bang on then ūüĎć

Where did you get the info from, out of interest.

Hi Stu, Severe Weather Europe post as of January 2020. You were bang on Stu, make a variable star observer of you yet, lol. 

Edited by Nigella Bryant
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Definitely not an expert in this field but I got a great look between storms this evening. Big hole in the sky from horizon to horizon but this will last one hour before the weather front rolls in.

Orion, the entire sky, constellation Orion, Taurus, and the surrounding constellations. Betelgeuse is sooooo dim. By naked eye, I would say one magnitude less than Rigel. Has this been the case at anytime in the viewable past?
 

Please bear in mind I am just one of you, so my idea of magnitude maybe less than scientific. On the other hand if a PHD wants a fist fight I am more than willing to apologise.

Marvin

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5 minutes ago, Marvin Jenkins said:

Definitely not an expert in this field but I got a great look between storms this evening. Big hole in the sky from horizon to horizon but this will last one hour before the weather front rolls in.

Orion, the entire sky, constellation Orion, Taurus, and the surrounding constellations. Betelgeuse is sooooo dim. By naked eye, I would say one magnitude less than Rigel. Has this been the case at anytime in the viewable past?
 

Please bear in mind I am just one of you, so my idea of magnitude maybe less than scientific. On the other hand if a PHD wants a fist fight I am more than willing to apologise.

Marvin

As I previously said, this last dimming cycle is quite unusual as the star is at record low brightness, and this dimming is significant enough to be seen by the naked eye. The latest data has the magnitude of the star at 1.5, which is 0.2 magnitudes dimmer than the previous known record of 1.3 magnitudes in 1927 and 1941.

Rigel is 0.18 and about 100+ light years more distant than Betelgeuse, which is at 1.5 at the moment and much dimmer than Rigel. 

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Before reading this, my estimate was 1.5. So I think that's probably about right given others have the same.

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I had a good look earlier; it seems to have dimmed even more compared to 2-3 weeks ago. If brighter than Bellatrix only by 0.1 mag or so, much fainter than Pollux, not noticeably brighter than Elnath or Castor. It looks more 2nd than 1st magnitude. I'd guess 1.6- it's unfortunate that Adhara (epsilon CMaj), which is about 1.5, doesn't rise more than a few degrees as it would be a good comparison.

Edited by Walshie79
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Also it is definitely closer to Castor than Pollux in terms of brightness

Edited by Walshie79
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Might be the conditions, but I'm seeing it a tenth brighter tonight.

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You can compare the brightness to others nearby. Standard variable star observing technique. Here's a comparison chart from CdC

Orion.thumb.png.a6ea108847354d0b7dc86a41c58ad6c2.png

I make it just a mite brighter than halfway between 1.2 and 1.6. So, around 1.4, maybe even a fraction brighter.

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Was thinking with today modem technology was there a good way , back in the 80s 9os  I was using my old proton detector .

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Reported from the astronomers telegraph. 

We report further on the recent unusual dimming of the red supergiant Betelgeuse (alpha Ori) reported previously in ATel #13341¬†and ATel #13365. We continue to carry out V-band and Wing TiO and near-IR photometry of the star. Since our last report, Betelgeuse has continued to gradually decrease in brightness. Our most recent photometry secured on 17.25 UT and 18.20 UT January 2020 yields: V = +1.494 mag and 1.506 mag, respectively. This is more than ~0.2 mag fainter than previously reported in ATel #13365¬†on 22.25 UT Dec. 2019. However during the last week or so the decline in brightness of the star may be slowing. As reported by Brian Skiff of Lowell Observatory (priv. commun.) visual estimates of Betelgeuse are available as far back as about 180-years ago. Systematic visual measures of the star have been made by AAVSO observers since the 1920s. More precise photoelectric photometry began nearly 100 yrs ago but systematic (mostly unpublished) photometry of Betelgeuse commenced about 40-years ago at Villanova Observatory by Scott Wacker and Guinan. Betelgeuse is now nearly as faint as (the slightly variable) B2 star Bellatrix (V ~+1.62 mag). Bellatrix (gamma Ori) is about 5√ā¬į west of Betelgeuse in the constellation Orion. The analysis of the calibrated Wing photometry (Wing 1992: JAAVSO 21, 42) returns measures of the temperature (via calibrated Wing TiO- and near-IR (B-C) color-indices) as well as estimates of bolometric magnitude (m-bol). The Wing intermediate band A-filter is used to measure the temperature-sensitive TiO 719-nm (gamma; 0, 0) molecular band. The B (750-nm) and C (1020.4-nm) filters are centered on relatively line-free stellar continuum regions. The C-band filter measures have been calibrated with K-M stars with bolometric magnitudes returning proxy measures of the apparent bolometric magnitude (m-bol) (see Wasatonic et al. 2015: PASP, 127, 1010). During the 25-years of V-band / Wing Near-IR photometry, Betelgeuse is currently the coolest and least luminous yet observed. Since September 2019, the star's temperature has decreased by ~100 K while its luminosity (inferred from the C-band/m-bol observations) has diminished by nearly 25%. At face value using R'/R = [(T'/T)^4 / L'/L]^0.5 (where R', T' and L' are the current values of stellar Radius, Temperature & Luminosity), this implies an increase of the star's radius of ~9%. However, as pointed out by others, the current fainting episode could also arise from expelled, cooling gas/dust partially obscuring the star. The recent changes defined by our V-band/Wing photometry seem best explained from changes in the envelop-outer convection atmosphere of this pulsating, unstable supergiant. If these recent light changes are due to an extra-large amplitude light pulse on the ~420-day period, then the next mid-light minimum is expected during late January/early February, 2020. If Betelgeuse continues to dim after that time then other possibilities will have to be considered. The unusual behavior of Betelgeuse should be closely watched.

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It’s gonna go bang in the next couple of days! If it does can I get credit and become the next astronomer Royal?

That last bit about expelling gasses must surely be the outer shell being ejected. So I must be in the pound seats.

Marv

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I just watched a video suggesting Betelgeuse won't go SN for quite a while. First, the gravitational waves possibly(!) detected in the Orion region don't seem to come from Betelgeuse itself. Second, Betegeuse is a very odd red giant in that it spins much faster than most, and shows much more nitrogen in its spectrum than it should. These phenomena could be explained easily if Betelgeuse is the result of a merger of a binary progenitor. The lain star would be 16 solar masses, the second about 4. The merger would increase the spin rate (some estimates suggest the surface velocity of 15 km/s, which would be HUGE, and contribute to matter escaping from the star), and also cause violent mixing of the materials from deep layers. This would bring nitrogen from the core to the surface, and simultaneously inject fresh hydrogen into the nucleus.  Seems to be one of the more sensible videos, despite the click-bait title

 

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Interestingly Betelgeuse does not appear to have dimmed in infrared wavelengths, only in the visual part of the spectrum. This would suggest that the dimming is caused by material obscuring the visible light. I look forward to seeing if Betelgeuse’s app mag starts to brighten through late Feb, March or not...

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15 minutes ago, PhotoGav said:

Interestingly Betelgeuse does not appear to have dimmed in infrared wavelengths, only in the visual part of the spectrum. This would suggest that the dimming is caused by material obscuring the visible light. I look forward to seeing if Betelgeuse’s app mag starts to brighten through late Feb, March or not...

I think material being expelled from the surface might well be the explanation.

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5 hours ago, michael.h.f.wilkinson said:

I think material being expelled from the surface might well be the explanation.

It seems that way, only the next month or so will tell. 

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I know I have made a joke, maybe two on this thread, but I am serious in saying that I am fascinated by the different ideas and observations.

I started my astronomy odyssey October 2018 knowing as close to nothing as you can get. The obvious thing at the beginning is that the stars are fixed ‚Äėunchanging‚Äô points of light. This incredibly dynamic change in one of, if not the most well known star (remember don‚Äôt say it three times) in the night sky is an opportunity to see in human time how much is changing.

Great stuff. Marvin

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Had a break in the clouds last night. Still seems to be hovering around 1.4.

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7 hours ago, bish said:

Had a break in the clouds last night. Still seems to be hovering around 1.4.

Should be brightening by now over the next few weeks but if it doesn't then it's unusual. 

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I told you all, it is going to bang in the next few weeks. Going to make and break astronomy for a couple of years at least.

Going to have something else to moan about... blooming weather and that annoying supernova, can’t see a thing. Do you remember the days etc etc.

The topic heading in on here may have to change to just Lunar, Solar and SN. Gonna needs shades. Feel sorry for anyone who has just bought a DSO Astro photo setup.

M

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On 31/01/2020 at 22:21, Marvin Jenkins said:

I told you all, it is going to bang in the next few weeks. Going to make and break astronomy for a couple of years at least.

Going to have something else to moan about... blooming weather and that annoying supernova, can’t see a thing. Do you remember the days etc etc.

The topic heading in on here may have to change to just Lunar, Solar and SN. Gonna needs shades. Feel sorry for anyone who has just bought a DSO Astro photo setup.

M

Excellent, that will make 3 things visible from my urban garden!

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Edward Guinan and other astronomers from Villanova University shared a brief update on Betelgeuse over the weekend, reporting it's now about one full magnitude fainter than it was in September.

It still continues to behave uncharacteristically. 

BANG - in my opinion. 

Edited by Nigella Bryant
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I was out observing last night and it is definitely on a magnitude par with Bellatrix (+1.6) rather than Rigel (+0.3) in the visible part of the spectrum. Still waiting for it to brighten (or explode ūüėČ). My all sky cam (which is mono and responsive to longer wavelengths) shows it more on a brightness par with Procyon and Rigel than Bellatrix... Obscuration!

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When red stars expand their light shifts into the infrared. This is why Mira type stars vary so much in brightness.

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