OT: When Betelgeuse goes supernova

[jillery]

The following is written by Jillian Scudder, who is a co-blogger with
Ethan Siegel. She answers the question "What happens when Betelgeuse
explodes?"

<https://medium.com/starts-with-a-bang/astroquizzical-what-happens-when-betelgeuse-explodes-c98e4673eaed#.tuuno7no1>

<http://tinyurl.com/h7ttkq3>

Short version: The actual question the article answers is "What will
people on Earth see when Betelgeuse goes supernova?" Scudder makes
the point that because Betelgeuse is about 600 light-years away, when
it actually goes supernova is offset by 600 years from when people on
Earth will see it, assuming there are still people on Earth by then.

One reason why this question is interesting is because, at over 11
solar masses, Betelgeuse is one of the closest stars to Earth that can
go supernova, that phenomenon being dependent on a star's mass.

Still, it's not expected to blow up for another 100k years or so. So
if there are people around Earth when the light of Betelgeuse's
supernova finally reaches Earth, what will they see? They will almost
certainly see a new star in the sky, about as bright as a
quarter-Moon. It will be impressive to be sure, but hardly
life-threatening. If it changes any lives at all, it will be by
inspiration only.

The article makes some misleading statements. It says Betelgeuse
"makes up the left hand shoulder of the warrior [Orion]". That is,
the observer's left hand. Since the constellation is facing you, that
would be Orion's right shoulder.

Also the article posts three photos. One is of Betelgeuse itself. For
scale, the blue haze surrounding the star is about the same diameter
as Jupiter's orbit. The other photos are of a supernova remnant
SN1006, at 7.2k light-years, and a runaway Wolf Rayet Star WR124, at
10.9k light-years. While these are indeed "wonderful pictures", they
are hardly "of the more nearby stars" than Betelgeuse. I assue the
author meant "nearby" relative to all other stars.
--
This space is intentionally not blank.

[erik simpson]

Orion is generally depicted as facing us, but that might very well be our
mistake. There's no reason to think he couldn't be looking the other direction,
either because there's something much more interesting over there, or he's
decently averting his eyes from the awful spectacle we present.

[jillery]

>Orion is generally depicted as facing us, but that might very well be our
>mistake. There's no reason to think he couldn't be looking the other direction,
>either because there's something much more interesting over there, or he's
>decently averting his eyes from the awful spectacle we present.

Cite any reference which has the Orion constellation drawn showing his
backside.

[Öö Tiib]

I have almost always seen Orion (when it is person, not distaff or scythe)
drawn not facing toward or away from us but with side. The right ear of
that "archer", "hunter", "chief" the artists imagine is towards us.

http://www.crystalinks.com/orionstarman.jpg

[jillery]

On Fri, 27 May 2016 23:42:57 -0700 (PDT), 嘱 Tiib <oot...@hot.ee>
wrote:

You describe the direction of Orion's face, which is usually in a
left-facing profile. The discussion above is about the body, which is
usually rendered full-frontal.

However, three points make this entire thread even more inane than I
suspect Eric intended:

1) <https://en.wikipedia.org/wiki/Leiden_Aratea> illustrates Orion
from behind, which directly answers my challenge above.

2) From the Southern Hemisphere, the constellation is viewed "upside
down", with its "head" pointing south, which apparently destroys its
appearance as a human form, and moots the point.

3) Native-American cultures also imagine no hunter, but various
animals, which also moots the point. Walksalone and/or Mark Isaak can
provide something authoritative about non-Western constellations.

[RonO]

It is part of that fine tuning thing again. If our star was part of a
denser cluster of massive star formation we likely wouldn't be here
today. Somehow we are surviving on the edge of one spiral arm of our
galaxy. Things would be different if we were in a denser cluster or
closer to the center of our galaxy.

Does the article indicate what would be the effect if the star was only
6 light years away? Square of the distance and two orders of magnitude
closer. It would probably be pretty toasty.

Ron Okimoto

[jillery]

[jillery]

On Fri, 27 May 2016 23:42:57 -0700 (PDT), 嘱 Tiib <oot...@hot.ee>
wrote:

You describe the direction of Orion's face, which is usually in a
left-facing profile. The discussion above is about the body, which is
usually rendered full-frontal.

However, three points make this entire thread even more inane than I
suspect Eric intended:

1) <https://en.wikipedia.org/wiki/Leiden_Aratea> illustrates Orion
from behind, which directly answers my challenge above.

2) From the Southern Hemisphere, the constellation is viewed "upside
down", with its "head" pointing south, which apparently destroys its
appearance as a human form, and moots the point.

3) Native-American cultures also imagine no hunter, but various
animals, which also moots the point. Walksalone and/or Mark Isaak can
provide something authoritative about non-Western constellations.

[jillery]

What you describe above is a variation of the anthropic principle;
things are not a certain way because if they were that certain way we
wouldn't be here to wonder why they aren't that way.

In the specific case of massive stars, there is another more relevant
factor, which is that their lifetimes, measures in just millions of
years, are very much shorter than average stars, which makes them very
much rarer in the Universe. Plus their short lifetimes provides much
less opportunity for biological evolution.

Similarly, most of the stars in the Universe are red dwarfs, because
they are incredibly long-lived; the smaller ones are expected to shine
for trillions of years.

[William Hyde]

It would be ten thousand times brighter than indicated in the article.

The sun is magnitude -27, the full moon -13, and a factor of ten thousand is ten magnitudes by definition, so the nearby supernova would be below magnitude -23. Wikipedia tells me a quarter moon is only ten percent as bright as a full one, a difference of 2.5 magnitudes, so our supernova is magnitude 21.5 or so, plus or minus a magnitude to account for imprecision in the original article.

Still, even magnitude -22 would be a percent of the sun's brightness, or about 3.4 Watts per square meter averaged over the top of the atmosphere. That would certainly warm things up if it persisted for long.

But I don't think we'd be worried about it, given the other dangers such as high energy particles.

The estimate of 100k years is pretty speculative. The star is not even particularly spherical much of the time "now" and might already have exploded (apologies for my sins against SR). Unlikely, but when I look at Orion, I wonder.

William Hyde

[J. J. Lodder]

The solar system condensed because a nearby supernova explosion
compressed a pre-existing gas cloud,

Jan

[Earle Jones27]

On 2016-05-27 22:10:23 +0000, jillery said:

> The following is written by Jillian Scudder, who is a co-blogger with
> Ethan Siegel. She answers the question "What happens when Betelgeuse
> explodes?"
>
> <https://medium.com/starts-with-a-bang/astroquizzical-what-happens-when-betelgeuse-explodes-c98e4673eaed#.tuuno7no1>
>
>
> <http://tinyurl.com/h7ttkq3>
>
> Short version: The actual question the article answers is "What will
> people on Earth see when Betelgeuse goes supernova?" Scudder makes
> the point that because Betelgeuse is about 600 light-years away, when
> it actually goes supernova is offset by 600 years from when people on
> Earth will see it, assuming there are still people on Earth by then.

*
Is it possible that Betelgeuse went supernova 550 years ago and in 50
years, we will see the result?

In the latest Scientific American (June, 2016 page 36) Daniel Kasen (UC
Berkeley and Lawrence Berkeley National Lab) reviews the types of star
supernovae: "Ordinary, Neutron Star Collision, Magnetar, False Alarm,
Particle Pair and Complete Collapse."

He concludes, "The death of a very big star would produce a remarkably
dim supernova."

earle
*

[jillery]

On Sun, 29 May 2016 15:32:49 -0700, Earle Jones27
<earle...@comcast.net> wrote:

>On 2016-05-27 22:10:23 +0000, jillery said:
>
>> The following is written by Jillian Scudder, who is a co-blogger with
>> Ethan Siegel. She answers the question "What happens when Betelgeuse
>> explodes?"
>>
>> <https://medium.com/starts-with-a-bang/astroquizzical-what-happens-when-betelgeuse-explodes-c98e4673eaed#.tuuno7no1>
>>
>>
>> <http://tinyurl.com/h7ttkq3>
>>
>> Short version: The actual question the article answers is "What will
>> people on Earth see when Betelgeuse goes supernova?" Scudder makes
>> the point that because Betelgeuse is about 600 light-years away, when
>> it actually goes supernova is offset by 600 years from when people on
>> Earth will see it, assuming there are still people on Earth by then.
>
>*
>Is it possible that Betelgeuse went supernova 550 years ago and in 50
>years, we will see the result?

Of course. And the only way to know for sure is to wait and see.

>In the latest Scientific American (June, 2016 page 36) Daniel Kasen (UC
>Berkeley and Lawrence Berkeley National Lab) reviews the types of star
>supernovae: "Ordinary, Neutron Star Collision, Magnetar, False Alarm,
>Particle Pair and Complete Collapse."
>
>He concludes, "The death of a very big star would produce a remarkably
>dim supernova."
>
>earle

It's important to be clear what Kasen means by "very big". A
convenient if anthropic measure of a star's "bigness" is the Solar
Mass, obviously referring to the mass of the Sun. Since the Sun
contains over 99% of all the mass in the Solar System, even one Solar
Mass is, from our personal perspective, very big, but that's not what
Kasen means by "very big".

According to the math, single stars of less than 8-10 solar masses
don't have enough mass, and so not enough gravity, to go supernova.
So, even though these stars are that much very bigger than our Sun,
that's not what Kasen means by "very big".

What Kasen means by "very big", is stars of 70-150 solar masses.
According to him, stars of masses in that range may go through
multiple "false starts" that appear as dim supernovae, but are really
just precursors to the main event.

Kasen also describes stars of 300-1000 solar masses. Their collapse
should result in a black hole. If so, the light from their supernovae
would be swallowed up almost instantly.

[Tim Norfolk]

I had to check, but Chandrasekhar's limit is about 1.44 times Sol's mass.

[jillery]

>I had to check, but Chandrasekhar's limit is about 1.44 times Sol's mass.

Correct, but keep in mind that applies to the mass of a neutron star.
In order for an ordinary star's core collapse to create a (potential)
neutron star, it must start out with much greater mass, at least 8-10
solar masses. The rest of the star's mass is either converted to
energy or blown out into space.

[J. J. Lodder]

The latter. A star goes supernova because it is out of fuel.
Almost all of the energy of a supernova explosion
comes from the gravitational collapse,

Jan

[jillery]

The question above isn't about where the energy of a supernova comes
from. Try to keep up.

[J. J. Lodder]

Is it so hard to admit being wrong about the mass of supernova
being converted into energy?
While some fusion energy may be produced in some outer layers
the main fusion energy -is negative-.
(iron nuclei being converted into free neutrons, that is un-fused
at a great energy cost)
The energy comes from gravitational collapse,
not from converting some of the mass into energy,

Jan

[jillery]

On Fri, 3 Jun 2016 20:48:42 +0200, nos...@de-ster.demon.nl (J. J.

The correct and relevant question here is, is it so hard for you to
stop your compulsive trolling? You're like a chain smoker, starting
up another one before you finish the previous.

I wrote nothing that would give a reasonable person the impression I
said anything like what you say I said.. What you're talking about
isn't even relevant to my point. Your question above is just another
one of your stupid lies.