Artist’s depiction of the G2 cloud being dispersed and swallowed during its close approach to Sagittarius A*
Universe Today story
Nature article
For a decade now astronomers have been tracking the progress of a dense gas cloud called G2 which now is rapidly approaching the Galactic center on a very eccentric elliptical orbit (eccentricity ~ 0.95) and is estimated to reach pericenter (the point of closest approach) around the beginning of July 2013. Tidal forces have already been observed to stretch the cloud and these forces will become increasingly strong over the next 9 months as the cloud approaches orbit pericenter at which point it is thought that they will be strong enough to completely rip the cloud apart. At this point the dispersed cloud is expected to be gravitationally drawn into the Galactic core with the consequent release of a large amount of energy in the form of cosmic rays and gamma ray emission.
I have been asked by several people whether the cloud’s consumption on this 2013 date might produce a Galactic superwave which would be reaching our solar system on that same date (due to the ability of the cosmic rays to travel straight toward us at close to the speed of light) and produce a major solar system cataclysm; e.g. see the forum comment by psychiceyes. Indeed, due to the ending of the Mayan calendar cycle on December 21, 2012, there are many who expect an end of world scenario or consciousness transition event. In fact, some groups have built shelters in the heart of Australia and South Africa with this expectation in mind.
I do not deny the possibility that a superwave could arrive in the next years. I have long maintained that we are overdue for such an event and give a 95% probability that a superwave (large or small) should arrive sometime in the next 400 years. However, it is difficult to make predictions before hand. Now, with this cloud having been detected in advance, the question arises whether this near approach event could be what triggers the long overdue Galactic core outburst and accompanying superwave. Indeed, studies and observations of the Galactic center similar to these reporting on the G2 cloud could give us advance warning about the potential arrival date of an impending superwave catastrophe.
I have looked at literature that has been published about this cloud, have considered all aspects carefully, and have reached the conclusion that this encounter could very well initiate an energetic flare from the Galaxy’s core as astronomers predict, but that this will likely not be powerful enough to produce a superwave. That is, it will not be sufficiently energetic to launch a cosmic ray volley that could locally overpower the interstellar magnetic field and allow long-range flight of the cosmic rays out of our Galaxy’s nuclear bulge. Also, if it were able to release cosmic rays along rectilinear trajectories towards us and produce a superwave, I don’t believe that the consequences would pose any kind of health hazard. Although there is a rather remote possibility (which I cannot presently rule out) that such a superwave may be a Magnitude 1 superwave that carries an electromagnetic pulse (EMP) and geomagnetic disturbance similar to a Carrington solar flare event, one that would be able to disrupt our electrical grid and satellite communication systems. Also a magnitude 1 event could possibly cause significant seismic activity similar to the December 2004 tsunami event that struck two days before our satellites registered the largest Galactic gamma ray burst in modern history. But these more serious EMP and gravity wave consequences should occur only if the G2 cloud break up and consumption occurred quickly, as we will discuss below.
One question that comes to mind is whether the G2 cloud has been orbiting the GC for some time. Its orbit is observed to have a period of 138 ± 11 years and we see that no unusual cosmic or auroral effects took place on Earth back in 1875. However, it seems that astronomers have come to conclude that it is making its first pass toward the Galactic center and that this cloud somehow originated for the first time around 1944 in the vicinity of the ring of blue giant stars that orbits the Galactic center. So this may be the cloud’s first close encounter with the GC. Whether there have been similar close encounters in the past centuries or millennia is left to speculation. Our ability to track such objects in the vicinity of the GC came into play mainly in the past decade. This G2 cloud was first discovered in 2006.
Murray-Clay and Loeb have theorized that a brown dwarf or low mass cool star is embedded in the G2 cloud, and that the cloud is regenerated from gasses boiling from the star’s surface. At its pericenter G2 will pass within 266 astronomical units (AU) of the Galactic center and at this distance the tidal forces are not strong enough to rip apart a star. They can disperse a cloud, but not disrupt a star. So whatever happens during this pericenter encounter will necessarily arise due to the accretion of the G2 cloud mass which is estimated to amount to about 3 earth masses (2 X 1028 grams). What transpires will depend on how fast the Galactic core accretes this cloud. Even our most sophisticated computer models cannot predict the kind of galactic roulette that will transpire during this encounter. So let us consider three possibilities:
a) Let us first consider the more likely possibility that most astronomers are suggesting, namely, that the dispersing cloud will be gradually accreted in small gulps over a period of around 20 years. The potential energy difference between the pericenter distance (~120 AU) and the core’s radius (~0.1 AU) will result in a total kinetic energy release of ~1049 ergs for the infall of a 3 earth mass cloud. If this infall occurs gradually over 20 years energy would be released at the rate of 1.5 X 1040 ergs/s. This is quite small compared to the cosmic ray luminosity of Sgr A*, which I estimate amounts to about 1043 ergs/s. This added energy then would produce a net 0.1 percent elevation of the core’s energetic activity which may not be easily seen above the core’s normal activity fluctuations.
b) Let us say as a second possibility that some time in this 20 year accretion interval that 10% of the cloud’s mass (i.e., 0.3 earth masses) were accreted in a discrete event lasting three days and energizing the side of Sgr A* that faces us. Then the energy release would rise to about 4 X 1042 ergs/s, hence producing a 40% increase of the core’s activity level. This would produce a noticeable increase in gamma ray emission, but certainly not generate a superwave or pose any kind of hazard to Earth. The Galactic core had been observed to produce a much larger flare than this in 2001 when X-ray emission was observed to rise 3 fold within a period of one hour (http://chandra.harvard.edu/photo/2001/0204flare/).
c) Suppose as an extreme that all of the 3 earth masses of this dispersed cloud were to crash onto the surface of the Galactic core within a period of one day. This would add a total of ~1049 ergs, or about the energy of a type I supernova explosion. If added to the core over a 1 day period this would amount to 1044 ergs/s, or to a 10 fold increase in the overall energy output of Sgr A* assuming it normally emits cosmic ray protons and electrons at the rate of 1043 ergs/s. The type 1a Tycho supernova, which was observed by Tycho Brahe in 1572 AD, involved a comparable release of energy and occurred at a distance three times closer than the Galactic center. While no harmful effects were observed to the Earth, the gamma ray burst from this explosion did cause an elevation in the ionization of the Earth’s atmosphere leaving a distinct nitrate ion peak in the Greenland ice record. A 2013 GC burst of this magnitude, but 10 fold weaker due to the greater distance, may also cause a noticeable elevation of atmospheric ionization. Whether this disturbance would be accompanied by an EMP that could adversely affect modern society is difficult to say — possibly, but probably unlikely.
d) There is a wild card to consider. That is, if the cloud contains an embedded brown dwarf, this star may be what is called a Hot Jupiter star. This is the observation that when Jupiter-like planets are located very close to their parent stars, say within 0.02 to 0.09 AU, their radius is found to be greatly inflated, in some cases by as much as 80% of their expected radius. This is believed to be partly due to the interception of the parent star’s energy flux and partly to frictional heating due to tidal forces, but the phenomenon is not well understood. A Jupiter-like dwarf star that approached near the the Galaxy’s highly luminous supermassive core would also experience a hot Jupiter effect, but far more extreme from that seen in stellar systems.
Let us consider a 50 Jupiter mass star which normally has a radius 70% of that of the Sun. Due to its close proximity to the Galactic core, its surface will be heated by the cosmic ray radiation being emitted from Sgr A*. It would intercept an energy flux of about 4 X 1032 erg/s, or about 10% of the Sun’s luminosity. Normally, a 50 Jupiter mass star should have a luminosity of around 3 X 10-4 solar luminosities. So this effect alone would boost the energy input into the star’s atmosphere by 330 fold. This added energy input would cause the dwarf’s heated atmosphere to expand far more than the 80% observed in sun-like star systems. If it were to expand say 4 fold to ~3 times the diameter of the Sun, its surface would intercept 16 times more energy, bringing the energy input to its atmosphere to 1.6 solar luminosities, or 5300 times greater than normal! In addition to this we must add the heating due to tidal friction. So, due to this added energy and expanded atmosphere, the dwarf would likely be expelling its atmosphere much more rapidly into space, thus contributing extra matter for accretion. How much this might increase the G2 cloud’s mass during its two year near approach passage to the GC is difficult to say.
Other articles on the G2 cloud include: http://arxiv.org/abs/1209.2272
and http://arxiv.org/abs/1201.1414
One last comment, for many years I have been against the black hole concept. My long research on this subject has led me to believe that black hole singularities are unable to form in nature and in fact that the evidence is contrary to their existence. In particular we now know enough about our own galactic core that we can conclude that the core is not a black hole, but rather a supermassive dense star. This evidence has been discussed in another posting (http://starburstfound.org/sqkblog/?p=115). I share the opinion of MIT professor Phillip Morrison that black holes “only exist in the minds of physicists and astrophysicists”. As a result, as you may note above I have used the theoretically neutral phrase “galactic core” in referring to Sgr A*. Calculations which are presented in my book Subquantum Kinetics (4th ed.) estimate that the core has a radius of ~0.1 AU. This happens to be very close to what standard physics proclaims is the black hole event horizon radius for Sgr A* which is 0.09 AU. So, the energy release calculations I have made above jive quite closely with what physicists estimate would be the energy released by matter falling through the event horizon of a black hole. The only difference is that in conventional black hole theory only a portion of this infalling matter would release energy that would be visible to the outside world. The rest, perhaps 90% would be irretreivably lost into the supposed black hole. But as I stated earlier, this whole black hole idea is an immense fiction.
Also those who have read Subquantum Kinetics will know that one of the arguments I cite against black holes being the power houses for active galactic cores is that the energy outpouring from such cores is so great that it pushes gas and dust far from the core. In fact, in many cases such active cores are seen to have swept their immediate vicinity clean of gas and dust. So this has left astronomers in the embarrassing position of not being able to easily explain how a black hole would be producing such prodigious energy outputs without any matter falling into them. Even if a massive blue giant star were to approach such a core and become tidally ripped to pieces, the wind would be so strong that this matter would be blown far from the core. None would reach its surface. So one is left to conclude that active cores are powered by their own source of energy generated spontaneously within them, what I call genic energy.
But what about a quiescent core such as that currently seen in our own Galaxy? In this case the outward energy flux is very low and insufficient to adequately expel gas and dust. That is why we have to worry about stars and close orbit passages to the Galactic center because a massive star passing close enough could produce an energy surge large enough to kick the core into its active state. For example, a 50 jupiter mass brown dwarf coming in as close as 1 AU to the Galactic center, could impart an energy jolt of 1.5 X 1053 ergs, equivalent to 150 of the most powerful type II supernovae. If injected in the course of one day, this could send the core’s energy output soaring to 1048 ergs/s, or 100,000 times its current output! This would be enough to kick the core’s genic energy output into a semi permanent active state such as that seen in the cores of Seyfert galaxies. It goes without mentioning, that this would launch a superwave that upon arrival at our solar system would have serious consequences, such as those that impacted us at the end of the last ice age.
Pray that this does not happen soon.
Paul LaViolette