Betelgeuse super nova

[Marvin Jenkins]

Apologies if this is in the wrong place, mods please feel to move it to the right heading. 
 

Now this may sound silly, but if I were to be viewing Betelgeuse with my 150 pds at the moment the light from it’s supernova explosion reaches Earth would I be in any physical danger of eyesight damage.

I thought don’t be rediculous, but after talking with an astronomer far more knowledgeable than I, his description made me wonder. I have read about a potential second sun in the sky, weak daylight on earth at night.

I did initially think it wouldn’t be any worse than viewing the moon but it dawned on me that it is a concentrated point of light not soft reflected light from a surface.

I ask this as we are aware of the dimming at present so perhaps we are getting close.

Marvin

[Ouroboros]

Supernovea take some time (days) to reach maximum intensity. Professional astronomers will have time to predict the maximum brightness and let us know whether or not there is any significant risk of eye damage.  

Edited January 9, 2020 by Ouroboros

[Owmuchonomy]

As far as I know it’s actually brightness when SN can only be roughly estimated so maybe yes, maybe no. Interestingly, imaging shows that it’s axis of rotation is not pointed at Earth otherwise we would be in serious danger of being hit by high energy radiation such as gamma. I also saw a presentation of a century of magnitude data which suggests the current dimming is not unusual. It’s a hot topic though 😎😁.

[RT65CB-SWL]

Betelgeuse is a slightly variable. It 'normally' averages +0.5 but estimates at the time of writing are saying that it is about +1.4  - to put it in to perspective...

Sun -26.2

full Moon -12.5

Mercury -1.5

Venus -4.5

Mars -1.5

Jupiter -2.5

Saturn -2.0

Sirius -1.0

...all magnitudes are approximate.

So get a variable polarising filter in case it does go supernova in our lifetimes and reaches the same magnitude as the full Moon.

Don't know why I still have ‘Champagne Supernova’ by Oasis doing the earworm thingy.

 

note: the '+' symbol is not normally shown on star charts and/or other astro-publications and that the magnitudes that I have used are visual magnitude not apparent magnitude to avoid confusion.

 

Edited January 10, 2020 by Philip R
more text plus Mercury, Mars and Sirius added.

[Space Hopper]

I wish Saturn was -2.0 !!

[robin_astro]

14 hours ago, Philip R said:

To put it in to perspective...

Sun -26.2

full Moon -12.5

Venus -4.5

Jupiter -2.5

Saturn -2.0

...all magnatudes are approximate.

So get a variable polarising filter in case it does go supernova in our lifetimes and reaches the same magnitude as the full Moon.

Don't know why I still have ‘Champagne Supernova’ by Oasis doing the earworm thingy.

Those are brightnesses integrated over the area of the object though.  The light from Betelegeuse as a supernova will be concentrated as a stellar point source.  For a telescope in typical seeing that would be about 300,000 times smaller in area than the sun or moon (equivalent to around 14 magnitudes) so the surface brightness of Betelgeuse when viewed through a telescope could indeed rival that of the sun so would certainly be dangerous and  potentially with the naked eye too, though type II supernova are a mixed bunch with a big spread in maximum luminosity.

Cheers

Robin

[robin_astro]

But as Ouroboros pointed out it will be  a week or two before it reaches maximum brightness in visible light so there is no danger of being unexpectedly accidentally blinded

[robin_astro]

The first evidence of it having gone supernova will be from a burst of neutrinos from the initial core collapse, some hours before the shock wave breaks though the outer surface of the star  and we see the first light from the explosion

[robin_astro]

That will be mainly high energy (gamma to UV) though initially.  We have to wait for it to cool a bit and for the energy from the decay of newly formed unstable elements to be generated to see the maximum in the visible light.

Edited January 10, 2020 by robin_astro

[Ouroboros]

After the initial explosion and over time it will become an ever expanding extended object. It will remain a very interesting object for astrophotographers for years. 

Does anyone here have any idea how large its apparent diameter might grow in the years following the explosion? 

Edited January 10, 2020 by Ouroboros

[robin_astro]

48 minutes ago, Ouroboros said:

Does anyone here have any idea how large its apparent diameter might grow in the years following the explosion? 

SN 1987A (another type II but a very different progenitor) was ~0.1-0.2 arcsec apparent diameter after 3.5 years according to this Hubble image

https://hubblesite.org/image/20

which given the ~300x difference in distance would suggest the Betelgeuse remnant would be perhaps Jupiter size in the same timescale?.  SN 1987A was made more interesting because is also lit up a ring of previously shed circumstellar material but I am not sure if there is much of that from Betelgeuse. (SN 1987A was a blue supergiant)

[Waddensky]

1 hour ago, robin_astro said:

The first evidence of it having gone supernova will be from a burst of neutrinos from the initial core collapse, some hours before the shock wave breaks though the outer surface of the star  and we see the first light from the explosion

There is a mailing list alert service for when those neutrinos are detected (for Betelgeuse or any other galactic core-collapse supernova): https://lists.bnl.gov/mailman/listinfo/snews-alert.

Still, the chances of Betelgeuse going supernova during our lifetime is very, very small.

 

[Waddensky]

1 hour ago, Ouroboros said:

After the initial explosion and over time it will become an ever expanding extended object. It will remain a very interesting object for astrophotographers for years. 

Does anyone here have any idea how large its apparent diameter might grow in the years following the explosion? 

The Crab Nebula (Messier 1) resulted from a core-collapse supernova in 1054 on a distance of about 6500 light-years. The current size of the remnant is about 420 arcsec, that's 0.4 arcsec per year. Correcting for the proximity of Betelgeuse (700 light-years) gives an expansion rate of about 4 arcsec per year. I'm sure the rate of expansion will decrease over time, though.

[Ouroboros]

32 minutes ago, robin_astro said:

SN 1987A (another type II but a very different progenitor) was ~0.1-0.2 arcsec apparent diameter after 3.5 years according to this Hubble image

https://hubblesite.org/image/20

which given the ~300x difference in distance would suggest the Betelgeuse remnant would be perhaps Jupiter size in the same timescale?.  SN 1987A was made more interesting because is also lit up a ring of previously shed circumstellar material but I am not sure if there is much of that from Betelgeuse. (SN 1987A was a blue supergiant)

 

22 minutes ago, Waddensky said:

The Crab Nebula (Messier 1) resulted from a core-collapse supernova in 1054 on a distance of about 6500 light-years. The current size of the remnant is about 420 arcsec, that's 0.4 arcsec per year. Correcting for the proximity of Betelgeuse (700 light-years) gives an expansion rate of about 4 arcsec per year. I'm sure the rate of expansion will decrease over time, though.

OK. Interesting. So there might be something to image through good scopes after a few years as long as the ejected material is suitably illuminated/emitting. 

[lukeEdfarley]

On 09/01/2020 at 08:02, Owmuchonomy said:

As far as I know it’s actually brightness when SN can only be roughly estimated so maybe yes, maybe no. Interestingly, imaging shows that it’s axis of rotation is not pointed at Earth otherwise we would be in serious danger of being hit by high energy radiation such as gamma. I also saw a presentation of a century of magnitude data which suggests the current dimming is not unusual. It’s a hot topic though 😎😁.

whoop my first ever post! anyways yes i heard the same thing...   the dimming is not unusual its the speed of the dimming they're getting excited about a bit of reading has told me that when it finally explodes it will be about half as bright as a full moon... (idk whether that prediction has any truth) however none the less rather spectacular me thinks. at the end of the day it's quite a long way away and considering intensity diminishes with the square doubt it will be blinding. that might be me underestimating supernovas though :)) it may be nice though a moon filter! haha.

[robin_astro]

1 hour ago, lukeEdfarley said:

whoop my first ever post! anyways yes i heard the same thing...   the dimming is not unusual its the speed of the dimming they're getting excited about a bit of reading has told me that when it finally explodes it will be about half as bright as a full moon... (idk whether that prediction has any truth) however none the less rather spectacular me thinks. at the end of the day it's quite a long way away and considering intensity diminishes with the square doubt it will be blinding. that might be me underestimating supernovas though :)) it may be nice though a moon filter! haha.

Supernovae put out a lot of light though (Around a billion or so times more luminous than the sun at visible wavelengths)  so yes, around the brightness of the full moon by  the time it gets here.  Something with the apparent size of a star in the sky producing as much light as the full moon will be painfully bright.

[Charles Kirk]

We only have accurate brightness estimates for around 100 years, a very short period compared to the 100,000 year timespan in which it is anticipated that Betelgeuse may become a Supernova.

I do think that it would be quite profound to see both the Sun and a Supernova in the sky at the same time.

Edited January 11, 2020 by Charles Kirk

[lukeEdfarley]

9 hours ago, robin_astro said:

Supernovae put out a lot of light though (Around a billion or so times more luminous than the sun at visible wavelengths)  so yes, around the brightness of the full moon by  the time it gets here.  Something with the apparent size of a star in the sky producing as much light as the full moon will be painfully bright.

ah right cool, i wonder how bright something has to be in order to cause problems for newt mirrors, course larger telescopes must be more susceptible to this.

https://www.rp-photonics.com/laser_induced_damage.html 

is an interesting page that outlines damage due to lasers.

I am aware that if you point a mirrored telescope at the sun without a filter in front you get some interesting burnt mirror arromas! 

the object you describe is very small but very bright so very intense, when this is reflected onto the secondary mirror will surely this intensity will go up could this pose a problem?

[verreli]

Betelegeuse is so far away that the photons arrive parallel from a point source in much that same way that photons are emitted from a laser.  As has been stated above, it will likely gradually brighten rather than switch on so no danger of retina damage, thereafter there will be no detail to see so there's no point looking at it - so don't.  A few years after it has faded away, it's likely to be the number one astronomy target as it grows and changes over time.  Orion may miss a shoulder but we'll be left with something far more interesting to look at and scientifically significant as the final stages before and after supernova can be studied.

[robin_astro]

7 hours ago, lukeEdfarley said:

 

the object you describe is very small but very bright so very intense, when this is reflected onto the secondary mirror will surely this intensity will go up could this pose a problem?

Not likely to be a problem for the secondary as the light (and heat) is unfocussed at that point  and being a mirror, most of the light and heat is reflected. But once focused then  a source as bright as the moon concentrated from a telescope of signifcant aperture onto a few pixels (or on the retina) would  be something to avoid

Edited January 11, 2020 by robin_astro

[robin_astro]

5 hours ago, verreli said:

thereafter there will be no detail to see so there's no point looking at it 

There would still be much of interest from a spectroscopic point of view though and something that bright would give professionals a big headache.  Even with my equipment I am not sure how I would cope. I would probably have to resort to defocusing and sampling the defocused image using the spectrograph slit as I did for Vega with this simple setup here for example

http://www.threehillsobservatory.co.uk/astro/spectroscopy_18.htm

(Off topic in this sub forum though)

Edited January 11, 2020 by robin_astro

[verreli]

Betelgeuse will still be of interest to the amateur astronomer.  It's visual observation with a scope that's not recommended during the SN period.  In addition to the spectroscopy that you mention, measuring the intensity of light over the weeks could be of interest.  Daylight / widefield astrophotography could also make an interesting photographic subject / record of the event.  Perhaps others could mention other ideas...

[Marvin Jenkins]

It seemed like a silly question when I posted it, but this is very interesting and I definitely did not expect the difference of options.  Was expecting ‘don’t be silly’ but I guess we are all a little in the dark when it comes to the real effects of Super Nova.

On a personal note I have decided to view Betelgeuse with my left eye. If I get blinded by the explosion I have saved my ep eye of choice.

Marvin

[Paul M]

Most of the intense radiation of the core collapse is screened from us by the outer layers of the star. Those take time to be disrupted and be ionized and eventually ejected into space by the core collapse. What does escape immediately is the glut of neutrinos created at that moment. They are effectively mass-less and beat everything else out of there. 

Don't worry. Apparently there are neutrinos passing through us in great numbers all the time. They won't wait to be focused by a telescope or captured by a CCD chip. They'll carry on their merry way, mostly!

[lukeEdfarley]

1 minute ago, Paul M said:

Most of the intense radiation of the core collapse is screened from us by the outer layers of the star. Those take time to be disrupted and be ionized and eventually ejected into space by the core collapse. What does escape immediately is the glut of neutrinos created at that moment. They are effectively mass-less and beat everything else out of there. 

Don't worry. Apparently there are neutrinos passing through us in great numbers all the time. They won't wait to be focused by a telescope or captured by a CCD chip. They'll carry on their merry way, mostly!

 

no haha they only bother with 100+ft of concrete or strangely i believe the detectors use water baths in caves but im not sure where i read that