21 votes
Accepted

Are stars expected to become dimmer before a supernova?

The connection between the dimming and a putative supernova relies on the interpretation that the decrease in luminosity may be due to circumstellar material, ejected in the years/decades/centuries ...
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  • 33.7k
20 votes

Is there any other theory to explain Betelgeuse's strange behavior except cosmic dust?

Recently (for about a year) Betelgeuse has been very stable, without any significant dimming or brightening (See its light curve, type "Betelgeuse" into the search box). There has been no ...
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  • 87.5k
17 votes
Accepted

What's the correct distance to Betelgeuse?

Distance measurements for Betelgeuse are a bit of a mess. Solutions based on parallax would be ideal, but Betelgeuse has a rather large angular diameter at most wavelengths thanks to its extended ...
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  • 33.7k
17 votes
Accepted

Daily magnitude of Betelgeuse

The American Association of Variable Star Observers tracks observations of a number of variable stars, including Betelgeuse. There are typically many such observations each day, primarily at visible ...
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  • 33.7k
11 votes
Accepted

What will it finally take to accurately measure the distance to Betelgeuse?

The problem is that the apparent diameter of Betelgeuse is about 50 mas (milliarcsecond --- 1 mas is about 5 nano-radians) while its parallax is about 5 mas and its shape and surface brightness are ...
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  • 9,893
11 votes
Accepted

Can New Horizons be used to measure the distance to Betelgeuse (despite its fickle photocenter)?

In principle yes, in practice no. The telescope is good enough, but the CCD camera will saturate, preventing a good positional measurement. Salient facts. The parallax to Betelgeuse as seen between ...
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  • 113k
9 votes
Accepted

How far from Betelgeuse is its habitable zone?

Nobody knows the limits of the Sun's habitable zone, or how broad or narrow it is. Here is a link to a list of various estimates of the inner, or outer, or both, edges of the circumstellar habitable ...
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9 votes
Accepted

Betelgeuse appears in a rainbow of colors through a Newtonian telescope

...pulsing bright rainbow of colors... Sounds like very bad astronomical seeing effects. Even a steady atmosphere acts like a weak prism and in fact all dielectrics tend to bend blue light more than ...
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  • 31.6k
8 votes
Accepted

If Betelgeuse is exploding in 2022, why would we see the explosion in 2022?

Light travels at a finite speed, 299 792 458 meters per second. Hence the term light year is the distance it takes light to travel in one year. Most of what is observed in the cosmos occurred some ...
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  • 1,446
8 votes
Accepted

Betelgeuse in false colors, is this common?

This is a partial and perhaps temporary answer only, posted in order to get to the bottom of this. I think that the comments are correct, you're probably seeing an artifact of image manipulation and ...
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  • 31.6k
7 votes

Will the nebula of Betelgeuse be visible to the naked eye? How bright, how large, how soon, for how long?

There is an article here that describes the visible effects quite well. In essence, within a week or so, it would be comparable in brightness to the moon and therefore visible during the day. ...
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7 votes

What will it finally take to accurately measure the distance to Betelgeuse?

So the Hipparchos parallax of Betelgeuse doesn't seem accurate enough? If only someone would launch an even more advanced astrometric satellite than Hipparchos. Actually the ESA has launched an ...
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6 votes

If Betelgeuse is exploding in 2022, why would we see the explosion in 2022?

Has Beteleguse exploded? No, as we have not seen the explosion. From the reference frame of the Earth we have not seen it explode (yet). It does not matter that in Betelgeuse's frame it may have ...
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  • 1,171
6 votes
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Do stars have "radio photospheres"? Are they different from their optical photospheres?

Stars certainly do have radio emission from their photospheres, since blackbodies emit at all wavelengths. But that’s not usually what is detected, because it’s so faint. Doing some simple numbers, ...
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  • 4,219
6 votes
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Would the Event Horizon Telescope be able to produce a superior image of Betelgeuse?

Presumably, yes, EHT observations could improve on existing radio observations of Betelgeuse (e.g. recent ALMA images and comparatively ancient VLA images). Any observations would likely be targeted ...
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  • 33.7k
5 votes

What star is the closest to Betelgeuse?

Barry Carter's nice piece of work contains 50 stars within $\sim 74$ light years of Betelegeuse. Leaving aside the question marks over exactly where Betelegeuse is (in terms of distance) and the ...
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  • 113k
5 votes
Accepted

What equipment and techniques were used to study Betelgeuse's diameter in 1920?

These measurements were made by Michelson & Pease (1921) using the 100-inch Cassegrain telescope at the Mount Wilson Observatory. Modern-day interferometry typically uses multiple telescopes (e.g. ...
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  • 33.7k
5 votes
Accepted

When we say a variable star is "fainting" does it mean something more or different than "dimming" or "fading"?

Saying a star is "fainting" is simply an error; the correct terminology is "dimming" or "fading". (I suspect it's a plausible mistake for non-native speakers if they know ...
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  • 14.7k
5 votes

Betelgeuse in false colors, is this common?

Whatever is causing these tiny artifacts, it isn't astrophysical. The image obtained by ALMA is monochrome , i.e. obtained through a single frequency channel (4GHz width at 338 GHz - see O'Gorman et ...
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  • 113k
5 votes

How far from Betelgeuse is its habitable zone?

Habitable zones, defined in terms of equilibrium temperature, scale with the square root of the luminosity of the star. So whatever the habitable zone limits $[a_{inner},a_{outer}]$ are for the Sun, ...
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3 votes
Accepted

Why does the Simbad page "A.A. Michelson's Jovian Galilean-satellite interferometer" show data for Betelgeuse?

The SIMBAD link might be there just because Osterbrock's 2004 AAS presentation about the interferometer mentioned an observation of Betelgeuse. This would be consistent with the policy stated in ...
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  • 16.5k
3 votes
Accepted

When Betelgeuse goes supernova, will the explosion hit any neighboring stars?

There have been 2 proposed spectroscopic companions, though never confirmed, traveling with Betelgeuse. These are thought to orbit the red supergiant. So when Betelgeuse eventually explodes, they ...
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  • 68
3 votes

What's the correct distance to Betelgeuse?

Current measurements give a distance "somewhere between 567 light years and 835 light years", with a "best guess" of 724 light years. So wikipedia is being honest and saying "...
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  • 87.5k
3 votes
Accepted

How can the radius of a star be measured using parallax?

Betelgeuse is large and close enough that it's angular diameter can be measured directly (via optical interferometry etc...) When you have the angular diameter, knowing the distance lets you ...
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  • 2,661
2 votes

Is there any other theory to explain Betelgeuse's strange behavior except cosmic dust?

There were certainly other theories to explain Betelgeuse's dimming. The big one is that perhaps there was a dark (cold) spot on the star. That's known as a "convective cell" (recall that ...
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  • 3,073
1 vote

If Betelgeuse dimmed because of dust, what became of the dust?

Whatever was the event that produced this ‘dust’ probably produced it isotropically (or at least isotropic to a good approximation) which, like you said, will either escape the orbit or not if ...
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  • 1,977
1 vote

Why does the Simbad page "A.A. Michelson's Jovian Galilean-satellite interferometer" show data for Betelgeuse?

Simbad is giving a catalogue of astronomical objects (that are identified in the Simbad catalogue) referred to in the AAS article. This is routinely done for most papers in the recognised astronomical ...
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