Now that I have addressed the misconception of where we (Solar System) is relative to the Galactic plane, I would like to continue the discussion of what is really important and that is what is happening in Sagittarius A. The black hole at the center of our Galaxy.
Where we are ‘relatively’ to the Galaxy was only mentioned because is seemed that this might be the case:
We might just be Hal, just not that lucky in being in the right place at the wrong time. Maybe we are, maybe we are not.
“One such young’un is the bright and shiny HR4796, a star 240 light years away, with about twice the mass of the Sun. It’s known to be less than 10 million years old — compare that to the Sun’s age of 4.56 billion years; we’re 450 times older! — and has also been known for some time to have material around it in the shape of a ring.”
“It’s huge; 22 billion km (14 billion miles) across, more than twice as wide as our entire solar system.
Again, the ring has been known for some time; for example it was seen in Hubble observations back in 2009. But there is some new stuff here. For one, if you look along the long axis of the ring, you can see it looks fuzzy. That’s real! The ring is made of dust grains of various sizes, probably the result of bigger clumps colliding with each other and grinding themselves up into ever-smaller pieces (the authors of this reasearch (PDF) call this a “collisional cascade”, my new favorite phrase for 2012). These grains of dust orbit the star, and the smaller ones get blown away from the star due to the pressure of its fierce light. Bigger grains are less affected, so they tend to stay in place.
So the main ring is made of bigger grains, while the smaller ones are blown back, forming a larger, extended ring. That fuzzier outer ring is fainter and harder to see, but we see it more easily along the long axis because of geometric effects (similar to why soap bubbles and giant shells of cosmic gas look like circles in space). So even though we only see a part of this outer ring, the fact that we only see it in those two spots is what makes it clear we’re seeing a ring at all! Funny how that works”
Why do I find this interesting? Well, this is an example of ‘Photoevaporation’.
http://en.wikipedia.org/wiki/Photoevaporation (again, not too wild about Wikipedia)
“Protoplanetary disks can be dispersed by stellar wind and heating due to incident electromagnetic radiation. The radiation interacts with matter and thus accelerates it outwards. This effect is only noticeable when there is sufficient radiation strength, such as coming from nearby O and B type stars or when the central protostar commences nuclear fusion.”
This is what the paper presented by the Smithsonian Institute of Astrophysics says will happen with the gas cloud now at the center of the Galaxy. (See part 2). What this means is that a similar ring of dust and debris should be expected to be ejected from the Galactic center in such and event. Remember, the example star shown above is just twice the size of ours, Sag A* is (at the lowest guess 40,000 times as large!) At the upper end, it is 4,000,000,000 times as large.
“It’s 26,000 light-years from Earth and Sgr A* is measured to be about 14 million miles across. This means that the black hole itself would easily fit inside the orbit of Mercury. How much mass is crammed inside this relatively small space? The lower mass limit of the black hole itself is calculated to be more than 40,000 Suns. However, the radio-emitting part of Sgr A* is a bit bigger, about the size of the Earth’s orbit around the Sun (93 million miles), and weighs much, much more – 4 billion Suns.
Black holes have such a strong gravitational pull that nothing – not even light, which is the fastest anything can go in our Universe – can escape it. You may think that black holes should be invisible because they don’t emit light, and suck up everything in the vicinity, but they can actually be very bright. This is because as matter bunches up around them, friction causes the gas and dust to heat up and emit light.”
What causes this? No one knows! You will hear stuff about ‘Solar Winds’ etc. Nope, that isn’t it otherwise it would be happening all the time, around every start that is visible. It is not, so this can be ruled out. All the material I can find on this subject is mostly about MASSIVE new stars and newly formed stars, when nuclear fusion starts. This star in our example is not massive at all! What has this to do with black holes? No one knows! Until recently, black holes were just a myth, predicted by Einstein’s theory of relativity but none were known or observed. Now they are everywhere, but basically very little is known about them. What we do know is that Galaxies have these same types of emissions, and all Galaxies have massive black holes in them at their center. The paper published by the Smithsonian states that Photoevaporation is to occur but this would NOT fit into the Wikipedia definition of the term but rather more like our example star shown above.
What we do know about the proto-solar system crashing into the black hole:
- It will create extremely bright light. This is already happening. It is 5 times as bright as the sun now! It will get really, really bright in the coming months. This is a fact. From our referenced article on this small star example:
- “the smaller ones get blown away from the star due to the pressure of its fierce light.”
We are therefore going to assume that the light created by this ongoing event will blow away (in a ring formation) the smaller material contained within this disk of gas/dust/planets creating a collisional cascade.
“The ring is made of dust grains of various sizes, probably the result of bigger clumps colliding with each other and grinding themselves up into ever-smaller pieces (the authors of this reasearch (PDF) call this a “collisional cascade”
Does this ring of material get larger or smaller over time? No one knows.
How fast does it travel? Since it is powered by light and other high energy emissions, one must expect it to travel at or near the speed of light. If it is to escape the gravity well of the black hole, it must be very fast. This is an assumption on my part.
Will it dissipate over time/distance? Who knows? I would expect that it would as it’s circumference is expanding (eventually to at least the size of the Galaxy itself!) and if it is dispersing a fixed amount of material it would be so diluted by the time it reached us to be virtually invisible. However, it may just pick more stuff up as it moves thru the Galaxy. Like a Tsunami. If nothing stops it, something will reach here. Based on what we see in other Galaxies with these ring emissions, it will be HUGE, i.e. it will collect stuff from the center out!
How big will it be? By that I mean, how TALL is it above/below the Galactic Plane along which it should be traveling. I would assume it grows in size as it dissipates from the core, so being above or below the plane is probably moot.
- Radiation emissions will occur This too is agreed on. Massive amounts of X-Ray radiation is expected to be produced as the mass of the cloud approaches the event horizon of the black hole. What I dispute is that this will have no effect on the earth or Solar System in general.
- First, dispel all notions, comments or misguided information that says we are too far away for this to have any effect.
- Behold this diagram:
- This shows how the center of our Galaxy ALREADY has emissions that we can observe that reach a distance of 25,000 light years from either pole. These emissions are EXACTLY what we are talking about: X-Rays (outer shell) and Gamma rays (everything else from our perspective, but see Gamma rays below for the explanation!)
- Nobody has ever explained to me how they get this picture, but I assume it is an artist’s rendition since it is from a perspective of perhaps 100,000 light years outside of our Galaxy.
- This is from the same group watching the cloud: Harvard-Smithsonian Astrophysics discovered November 10, 2010.
“On November 9, 2010, Doug Finkbeiner of the Harvard–Smithsonian Center for Astrophysics announced that he had detected two gigantic spherical bubbles of energy erupting to the north and the south from the center of the Milky Way, using data of theFermi Gamma-ray Space Telescope. The diameter of each of the bubbles is about 25,000 light-years (7.7 kpc); they stretch up to Grus and to Virgo on the night-sky of the southern hemisphere. Their origin remains unclear, so far.”
The Chandra X-Ray observatory shows us an example of an X-Ray explosion ring.
“All three structures are thought to represent shock waves produced by matter rushing away from the superstar at supersonic speeds. The temperature of the shock-heated gas ranges from 60 million deg Kelvin in the central regions to 3 million K on the outer structure. “The Chandra image contains some puzzles for existing ideas of how a star can produce such hot and intense X-rays,” agreed Prof. Kris Davidson of the University of Minnesota. Davidson is principal investigator for the Eta Carina observations by Hubble. “In the most popular theory, X-rays are made by colliding gas streams from two stars so close together that they’d look like a point source to us. But what happens to gas streams that escape to farther distances? The extended hot stuff in the middle of the new image gives demanding new conditions for any theory to meet.”
Yes, what does happens to gas streams that escapes to farther distances? Again, don’t expect answers soon. They mention yet another possible source of X-Rays, but really, they are just guessing.
This is what an X-Ray is:
X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma rays.
This is where they come from when not created by your doctor or dentist:
X-ray emission is expected from astronomical objects that contain an extremely hot gas at temperatures from about a million kelvin (K) to hundreds of millions of kelvin (MK). Although X-rays have been observed emanating from the Sun since the 1940s, the discovery in 1962 of the first cosmic X-ray source was a surprise. This source is called Scorpius X-1 (Sco X-1), the first X-ray source found in the constellation Scorpius. The X-ray emission of Scorpius X-1 is 10,000 times greater than its visual emission, whereas that of the Sun is about a million times less. In addition, the energy output in X-rays is 100,000 times greater than the total emission of the Sun in all wavelengths. Based on discoveries in this new field of X-ray astronomy, starting with Scorpius X-1, Riccardo Giacconi received the Nobel Prize in Physics in 2002. It is now known that such X-ray sources as Sco X-1 are compact stars, such as neutron stars or black holes. Material falling into a black hole may emit X-rays, but the black hole itself does not. The energy source for the X-ray emission is gravity. Gas is heated by the fall in the strong gravitational field of these and other celestial objects.
So, based on this description we should see high X-Ray radiation occurring and it has and will be able to reach us at 26000 light years distance. Please note that the black hole itself DOES NOT emit X-Rays, only the material falling into it. This is a fact and the picture you see above has SERIOUS implications based on this information. Keep reading.
- Gamma Rays This is the REALLY BAD JUJU, BWANA! This is the stuff that will wipe out a planet! See those purple areas in the picture above? Everything in them is dead (if it were already alive). If this type of radiation hits us, we are goners. Do not stop here, lets at least review what they are:
- Basically, they really have no idea about this stuff, but this is what they say:
- What potentially can create Gamma Rays?
Because of the immense distances of most gamma-ray burst sources from Earth, identification of the progenitors, the systems that produce these explosions, is particularly challenging. The association of some long GRBs with supernovae and the fact that their host galaxies are rapidly star-forming offer very strong evidence that long gamma-ray bursts are associated with massive stars. The most widely accepted mechanism for the origin of long-duration GRBs is the collapsar model, in which the core of an extremely massive, low-metallicity, rapidly rotating star collapses into a black hole in the final stages of its evolution. Matter near the star’s core rains down towards the center and swirls into a high-density accretion disk.
The infall of this material into a black hole drives a pair of relativistic jets out along the rotational axis, which pummel through the stellar envelope and eventually break through the stellar surface and radiate as gamma rays.
Some alternative models replace the black hole with a newly formed magnetar, although most other aspects of the model (the collapse of the core of a massive star and the formation of relativistic jets) are the same.
It is unclear if any star in the Milky Way has the appropriate characteristics to produce a gamma-ray burst.
Chandra already shows us one. Sag A*. Don’t these guys talk amongst themselves?
The massive-star model probably does not explain all types of gamma-ray burst. There is strong evidence that some short-duration gamma-ray bursts occur in systems with no star formation and where no massive stars are present, such as elliptical galaxies and galaxy halos.
The infall of matter into the new black hole produces an accretion disk and releases a burst of energy, analogous to the collapsar model.
How does this actually happen you ask?
The means by which gamma-ray bursts convert energy into radiation remains poorly understood, and as of 2010 there was still no generally accepted model for how this process occurs.
Particularly challenging is the need to explain the very high efficiencies that are inferred from some explosions: some gamma-ray bursts may convert as much as half (or more) of the explosion energy into gamma-rays.
In other words, electrons moving at light speed bump up against photons (also travelling at light speed) and convert them to Gamma rays. Not possible in Einstein’s world, but we will go with it.
The nature of the longer-wavelength afterglow emission (ranging from X-ray through radio) that follows gamma-ray bursts is better understood. Any energy released by the explosion not radiated away in the burst itself takes the form of matter or energy moving outward at nearly the speed of light.
As this matter collides with the surrounding interstellar gas, it creates a relativistic shock wave that then propagates forward into interstellar space. A second shock wave, the reverse shock, may propagate back into the ejected matter. Extremely energetic electrons within the shock wave are accelerated by strong local magnetic fields and radiate as synchrotron emission across most of the electromagnetic spectrum. This model has generally been successful in modeling the behavior of many observed afterglows at late times (generally, hours to days after the explosion), although there are difficulties explaining all features of the afterglow very shortly after the gamma-ray burst has occurred.
Sometimes you can just tell that they are guessing, but hidden in that statement is that Gamma Rays are produced in the shock wave magnetic field in the leading edge of this explosion.
Ok, what is so bad about Gamma Rays?
All the bursts astronomers have recorded so far have come from distant galaxies and have been harmless to Earth, but if one occurred within our galaxy and were aimed straight at us, the effects could be devastating. Currently orbiting satellites detect an average of about one gamma-ray burst per day.
Measuring the exact rate is difficult, but for a galaxy of approximately the same size as the Milky Way, the expected rate (for long GRBs) is about one burst every 100,000 to 1,000,000 years. Only a small percentage of these would be beamed towards Earth. Estimates of rates of short GRBs are even more uncertain because of the unknown degree of collimation, but are probably comparable.
Gamma-ray bursts are thought to emerge mainly from the poles of a collapsing star. This creates two, oppositely shining beams of radiation shaped like narrow cones. Planets not lying in these cones would be comparatively safe; the chief worry is for those that do. [80
For thick atmosphere planets, a gamma-ray burst’s ultraviolet rays would kill 90 percent of D. radiodurans at distances ranging from 13,000 to 62,000 light years.
Life surviving that onslaught would have to contend with a third effect, depletion of the atmosphere’s protective ozone layer by the burst. This would kill 90 percent of D. radiodurans at up to 40 percent of the distance across the Milky Way.
For example, if WR 104 were to hit Earth with a burst of 10 seconds duration, its gamma rays could deplete about 25 percent of the world’s ozone layer. It would create mass extinction, food chain depletion and starvation. The side of Earth facing the GRB would receive potentially lethal radiation exposure, which can cause radiation sickness in the short term, and in the long term result in serious impacts to life through ozone layer depletion.
You want to know what will jack up your DNA, Gamma Rays.
When gamma radiation breaks DNA molecules, a cell may be able to repair the damaged genetic material, within limits.
They don’t last long (seconds), they travel really fast, they go really far, and they are really, really bad if pointed in your general direction. Lets hope this does not happen.
- Time frame Well it is occurring right now, as we speak, relatively speaking. We see a large quantity of matter falling into our local black hole. You see what can happen when this occurs. What will be the result? As I said, we do not know, but it will not be NOTHING as stated by our friends at Science.com. Let us hope we are not Hal the deer with a target painted on us.
- Distance 26000 light years. That is how far away we are from whatever happened. Distance is our friend in this scenario. The light of the event will reach us sooner than the result. How much? Depends on what and how fast. Seems to me everything happens at or near light speed, so pretty quick I imagine.
- What does it mean to us? Watch this space! Be prepared to party as there is no place to run.
- That is everything, right? Sorry to say, no. Remember that there is this shock wave of magnetism, dust, and highly energetic particles ACROSS THE SPECTRUM, barrelling down the Galactic Plane? Well that is part 5.