Andromeda

[Fallingstar1971]

In reference to this article:

http://www.space.com/scienceastronomy/0 ... er-tm.html

If Andromeda (M31) acted up like this, would we even stand a chance??

Star

 

[crazyeddie]

In reference to this article:

http://www.space.com/scienceastronomy/0 ... er-tm.html

If Andromeda (M31) acted up like this, would we even stand a chance??

Star

Gamma ray flares, like gamma ray bursts, are highly directional. Andromeda's rotational axis would have to be pointed towards the Milky Way for it to do us any damage, and it isn't. However, I recall viewing a show on the Science Channel that described this scenario for a pair of distant galaxies. The energetic jets one active galaxy was emitting along it's rotational axis was pointed directly at a nearby galaxy in it's local cluster. There was speculation that no life could exist anywhere in the hapless galaxy that was unfortunate enough to be in it's path.

 

[js117]

If a Gamma ray flares was pointed at the Milky Way galaxy from the Andromeda M31 we may be dead ,
but not for a very long time 2000000 years.That if it happened today.

 

[bdewoody]

If a Gamma ray flares was pointed at the Milky Way galaxy from the Andromeda M31 we may be dead ,
but not for a very long time 2000000 years.That if it happened today.

Yeah, but it may have already happened 1,999,999 years ago, hehe.

 

[R1]

Does all of this mean that galactic core GRBs are only polar events and galactic discs always form
in between core magnetic poles?

I also wonder now about global galaxies. I mean globular. These do not rotate? Or they have no
magnetic poles? Or they have no poles and/because they do not rotate? Or do they lack a
galactic core leadership?

 

[R1]

If a Gamma ray flares was pointed at the Milky Way galaxy from the Andromeda M31 we may be dead ,
but not for a very long time 2000000 years.That if it happened today.

Yeah, but it may have already happened 1,999,999 years ago, hehe.

If all galaxy cores in the entire universe exploded 24,999 years ago with enough force to destroy the entire galaxies, we
would not know it either yet, would we? I think the answer is no, because the Milky Way core is 25,000 light
yrs. away.

:shock:

 

[neilsox]

I have not seen any numbers, so I will guess: Assume one watt per square kilometer = one milliwatt per square meter. This should do little or no damage to Earth's upper atmosphere and only about a millionth part of the gamma rays reach Earth's surface. Earth would absorb about 60 megawatts. The beam is much wider than Earth (about two million kilometers/narrower is likely not possible even as close as 10,000 light years)) so total energy is perhaps ten trillion watts = 10,000 gigawatts = 10 terawatts. If the energy source is 10,000 light years from Earth (possible briefly when Andromeda collides with the Milky Way in about ten billion years)
Earth passing through the hub of Andromeda has lots of potential for orbit change and other trouble. The beam from Andromeda's super massive black hole may be much stronger than the 10 terrawatts, I suggested in about ten billion years = we will be toast. The energy of the beam is approximately proportional to the amount of matter just outside the event horizon in the accretion disk. This can change radically in ten billion years. Please correct if my guesstimates are wrong. Neil

 

[bdewoody]

If a Gamma ray flares was pointed at the Milky Way galaxy from the Andromeda M31 we may be dead ,
but not for a very long time 2000000 years.That if it happened today.

Yeah, but it may have already happened 1,999,999 years ago, hehe.

If all galaxy cores in the entire universe exploded 24,999 years ago with enough force to destroy the entire galaxies, we
would not know it either yet, would we? I think the answer is no, because the Milky Way core is 25,000 light
yrs. away.

:shock:

Do you mean if the Milky Way galaxy's core exploded? You statement as is makes no sense.

 

[neilsox]

R1 is correct about the time delay, but galaxies don't explode and super massive black holes don't explode. Black holes typically send out a weak, but very narrow beam of gamma photons along the axis of their pole of rotation. Sometimes the beam is very powerful and is thus a danger to nearby galaxies. We are unsure of the degree of danger as the atmospheres of planets give lots of protection to the surface dwellers. Neil

 

[R1]

Thanks, neilsox, you did understand and explained it better.

I was referring to the fact that we really do not know what any galactic cores in the universe have been up
to for the last 24,999 years. Whether galactic cores exploded most violently, vanished into nothing,
or became strangelet mega centers 24,999 years ago, we still may not know because of the time delay
involved.

I guess I was basically taking the better known scenario that has the Sun inexplicably suddenly vanishing.
The story goes that we would not know anything had hapened to the Sun for 8 minutes...because of the time delay invoved. And I took this same scenario and applied it to galactic cores.

But anyway yes, bdwoody, glactic cores have not done anything that ruined earth yet that we know of.
...in the last 24,999 years. :?

 

[origin]

R1 is correct about the time delay, but galaxies don't explode and super massive black holes don't explode. Black holes typically send out a weak, but very narrow beam of gamma photons along the axis of their pole of rotation. Sometimes the beam is very powerful and is thus a danger to nearby galaxies. We are unsure of the degree of danger as the atmospheres of planets give lots of protection to the surface dwellers. Neil

Our atmosphere is very good at stopping charged particles, it is much less effective at stopping gama rays. A high flux of gama rays would be a very bad thing to happen to the earth.

 

[bdewoody]

Thanks, neilsox, you did understand and explained it better.

I was referring to the fact that we really do not know what any galactic cores in the universe have been up
to for the last 24,999 years. Whether galactic cores exploded most violently, vanished into nothing,
or became strangelet mega centers 24,999 years ago, we still may not know because of the time delay
involved.

I guess I was basically taking the better known scenario that has the Sun inexplicably suddenly vanishing.
The story goes that we would not know anything had hapened to the Sun for 8 minutes...because of the time delay invoved. And I took this same scenario and applied it to galactic cores.

But anyway yes, bdwoody, glactic cores have not done anything that ruined earth yet that we know of.
...in the last 24,999 years. :?

I got it after neilsox expanded but my point is that Andromeda's core could have exploded a very long time ago and the news would be forthcoming very soon, however I think the obsevations made so far do not support the probability that Andromeda or any other nearby galaxy is/was on the verge of such a calamity.

 

[R1]

A very long time ago Andromeda could not have exploded, all galaxies began to form at around
the same time everywhere. We need to give Andromeda and all galxies time to form first.

So a very, very long time ago, Andromeda and all the galaxies started to form.

Then, a very long time ago, they all appeared to be where and how they look today.

Sometime between the two epochs above, the universe decided inexplicably and against all
known laws of the time, to constatly accelerate its expansion.

If for some reason the universe decided (illegally to current knowledge) to make strangelet
mega centers out of galactic cores, explode
them harmfully, or vanish them inexplicably 24,999 years ago, we would not know it...yet.

The first ones to find out, unfortunately, could be earth, if things do happen quite homogeneously
and simultaneously throughout the universe, because of the time delay being the smallest within the
Milky Way.

 

[neilsox]

We have invested a lot of effort studying and measuring the laws of plysics. There is a tiny bit of not very good evidence of abrupt changes in the long ago past. If an abrupt change occured at one location (our super massive black hole) it would likely spread at the speed of light, or less.
The effect would reach Earth in about 24,000 years and Andronomeda in about 2 million years. In subsequent years it might start independently in a few other locations, thus reaching much of the Universe in a few billion years.
Some of the galaxis may have started forming shortly after the big bang, but the Milky Way galaxy waited about 4 billion years to organize so likely the big bang was the last, and only, thing that occured simultaneously everywhere. Neil

 

[R1]

The onset of constant acceleration of expansion too, must have been homogeneous* and
simultaneous, I bet.

*My understanding is that dark energy is observable in large, empty voids, as opposed to near galaxies,
but nevertheless ubiquitously within the observable sphere in the manner described.

But it's a bet at the most. Maybe I can be corrected about it.

------------

What did the Milky Way wait 4 billion yrs. to form relative to?
Andromeda?
The Big Bang?
or most other galaxies?

 

[neilsox]

I was thinking 4 billion years after the big bang. Some galaxies likely formed less than a billion years after the big bang, and a few may still be forming. Perhaps the Milky way was typical at 3.7 billion years or their abouts. Neil

 

[js117]

A little off subjet but isn't the Andromeda ( m31 ) going to colide with Milkyway gallaxy in a few billon years.
This will be a liitle more destuctive.

 

[R1]

Iirc they will start an official merger in about 3 billion yrs.

The solar system could get thrown far away from the Milky Way as the galaxies
conduct their business, completely unharmed by Andromeda, but life on earth will be history long before that
(2 billion yrs. before) due to the gradual warming of the Sun.
[Due to Internal solar system problems unrelated to Andromeda]





edit/add... The Milky Way has already done a merger/acquisition
(with the Sagittarius galaxy or something like that), by the way.
Parts of it are here and big parts of it are on the other end of the Milky Way, I think :

 

[crazyeddie]

R1 is correct about the time delay, but galaxies don't explode and super massive black holes don't explode.

Beg to differ:

Astronomers using the Subaru Telescope have discovered an exploding galaxy at the edge of the known universe.

The team, led by astronomers from Tohoku University in Japan, say the galaxy rapidly formed stars when the Universe was less than a billion years old. Images and spectra from the Subaru and Keck telescopes reveal that the galaxy has a high-speed outflow of hydrogen gas believed to be caused by a massive burst of star formation.

http://www.space.com/scienceastronomy/s ... 20823.html

And then there's M82, "The Exploding Galaxy":

 

[R1]

wow

:shock:





Interesting.