Essay added 11/5/02
ETA CARINAE, HOW DOES IT WORK?
Current Knowledge
Robert Zimmerman [1] states, "Eta Carinae - the biggest, star in the Milky Way - has started brightening again, and no one knows why or where it might lead. Yet, Eta Carinae's place in stellar evolution is crucial. Its mysterious behavior challenges every theory that tries to explain the life and death of stars - including our own sun."
"Eta Carinae was considered an unusual but undistinguished variable star, sometimes glowing at 4th magnitude, sometimes at 2nd. Then in the 1830s, John Herschel noticed that the star's light had risen steeply and, by December 1837, had reached 1st magnitude. Puzzled by this strange jump in brightness, Herschel researched the history of the star and discovered that it had also reached 1st magnitude in 1827 and again in 1832. After fading in 1838, the star blazed forth in 1843, zooming to a magnitude of -1 and becoming, for a short period, the (sic) brightest star in the sky, eclipsed (usually) only by Sirius." Sirius, the brightest star in the sky, defines the 0th magnitude scale.
"The most obvious features in the Hubble image (see Figure) are the two large and grayish bipolar lobes, shaped somewhat like an hourglass. With a total mass somewhere around three times that of the sun, their glow comes mainly from starlight radiated by Eta Carinae that reflects off the ubiquitous dust in the lobes. Ejected from the star during the 1843 eruption, each lobe is expanding outward at the rate of about 1.5 million miles per hour. The lobes apparently formed when matter was ejected from the star's polar regions."
"Within the Paddle itself, however, several small regions move at much slower speeds, as low as 30,000 miles per hour. These relatively sluggish speeds imply that the features were ejected from Eta Carinae several hundred years ago, long before the eruptions of the 19th century."
"All the data gathered about the equatorial disk so far presents scientists with an exceedingly confusing picture of its origin. Depending on when and where they look, different astronomers get different results. The disk appears to be the accumulation of many outbursts. Although astronomers regard Eta Carinae as one of the largest and brightest stars in the Galaxy, it has never been viewed directly, hidden as it is within the gigantic cloud that surrounds it."
"Eta Carinae appears to tip the scales at a mass 100 to 120 times larger than the sun. What causes these larger eruptions remains a mystery, though astronomers suspect the incredibly high mass and temperature play key roles. The most popular hypothesis says that the star's luminosity is so great that it occasionally overpowers the gravity that holds the star together. The star becomes unstable; its outer layers pulse in and out as if unsure whether they wish to remain in place or gush into space. Eventually an eruption occurs and the outer layers are flung away. With the loss of this shell of hot gas, the star cools and its surface temperature drops to a relatively low 13,000° Fahrenheit. At the same time, its electromagnetic output shifts from the high-energy ultraviolet to less energetic optical radiation, so though the star is now cooler, it radiates more brightly at wavelengths our eyes can see. Hence, while the star seems brighter, its overall output undergoes no intrinsic change."
"After an eruption, these strange stars become stable for long periods, with their visible luminosity generally holding steady (though small, irregular fluctuations are not unusual). Whether the huge outbursts happen more than once is simply not known. If so, they are separated by thousands of years."
"It is also far from clear whether the war between gravity pulling inward and the pressure of radiation pushing outward is the sole cause of these giant eruptions. Some scientists think that turbulence and convection on the star's surface either contributes to or causes the outbursts. Others believe that no current theory can be correct because none seems to explain adequately what instigates the eruptions as well as what makes them stop."
"As of June 1999, the star and the surrounding Homunculus glistened at about 5th magnitude, the brightest it has been since the Great Eruption in 1843 (see Figure). An increase in brightness across the entire electromagnetic spectrum implies that Eta Carinae is growing intrinsically brighter, a possibility no theory predicted. Moreover, this brightening implies that the star's luminosity may soon overwhelm its gravity, once again causing the star to become unstable and erupt as it did in the last century. 'And Eta Carinae can't brighten very much,' notes Humphreys, 'or else it will go boom.' "
"Based on this cycle, a number of astronomers immediately proposed that Eta Carinae was actually a binary system with both stars hidden by the system's dense surrounding nebula - and that all previous eruptions might have been caused by the orbital interaction of two stars. Unfortunately, no proposed binary system has yet explained Eta's behavior completely. Some have even considered the possibility that the system is comprised of a barely stable three-star system."
Proposed New Energy Release Mechanism [2]
The Milky Way Galaxy has a number of such stars called cataclysmic variables, part of a larger class of variable or unstable stars. One look at the luminous blue star Eta Carinae would be enough to convince anyone that this star is in its death throes. Eta Carinae is a southern hemisphere object, and has been quite familiar to observers throughout the centuries. Edmond Halley watched it brighten up to 4th magnitude in 1677. Roughly, 170 years may represent the cycle time of Eta Carinae.
The primary question is, what process accounts for the periodic brightening and the long quiescence of Eta Carinae? If Eta Carinae is truly a binary pair of almost equal mass cores, and if the cycle is truly periodic on an approximately 170 year period, then what might account for its increasing peak brightness every cycle? Will it reach another, even brighter peak in approximately 2010, as it's recently observed increased brightness suggests will happen? And will it survive another cycle, or go supernova next time?
What comes to mind as an analogy is a pair of equal-sized steel balls suspended by wires from a common point. When pulled apart and released, they collide and bounce elastically from each other on a fixed period, striking several times before finally coming to rest. If an energy release mechanism could be invoked at the point of contact, triggered by the strength of the collision, then the process could be stabilized. In fact, this is precisely the mechanism used in a pendulum clock, where the pawl adds just enough energy from the weights each tick to compensate for the frictional energy losses. If excess energy were added, then the stroke of the pendulum would actually increase every cycle until compensated by increased losses somewhere.
Think of Eta Carinae as a binary pair of bouncing stars! Perhaps a third body was needed to cause them to collide in the first place, but once they collided, an energy release mechanism at the interface caused them to part again, moving away somewhat faster than they were initially moving together. The sudden energy release accounts for the subsequently observed brightness peak. The period during which they move away and then re-approach is the quiescent period. The next collision is stronger than the previous one, leading to a greater energy release, increased brightness, and an even faster departure than before! At some point, the reaction has to become so violent that the result is a supernova.
Let us consider the mechanical collision of two star cores as pictured in the Figure below. As they collide, the vast kinetic energy of motion is converted to mechanical compression of the interface zone. Since this matter has nowhere to go, its density must increase dramatically. It is postulated here that the conditions for a Chandrasekhar collapse of the atoms in the interface zone are met, so that the interface behaves somewhat like the collapse of the iron core in a Supernova Type-II. Remember that the two cores are each about 60 solar masses, so it is not unreasonable to expect that the crush zone can approach 2 to 3 solar masses. At this point, we have a miniature somewhat confined supernova, and it acts to arrest the motion, turn it around, and blow the damaged cores apart again.
The situation just after the explosion is shown in the Figure below, where the asymmetric effect of the explosion can be responsible for creating the lobes and the Paddle.
To summarize, first, there is obviously a power release mechanism present that turns the inelastic collision of the cores into a situation where they recede from one another with greater speed than they had when they collided. Second, the light outer layers are explosively ejected away from the point of collision in a 3-dimensional pattern that could account for the Keyhole Nebula, observed for a few years after the 1843 eruption (see Figure) when the cores were still close together, and then account for it vanishing when the cores separated and gravity carried the outer layers along the direction of motion of the cores. Third, the energy mechanism cannot be based on fusion that takes place when the outer layers combine, because the amount of energy required is too large. And finally, the mechanism must be explosive, and in fact must be concentrated in a small region around the collision interface if the two cores are to be ejected in essentially whole pieces.
In the present case, the interface collapse is collision-generated, and occurs at a rate governed by the speed of approach of the two cores. For a supernova, the present theory is that an outward-directed shock wave is formed when the central core reaches full compression, and this shock wave manages to blow the outer portion of the star away. The neutrinos released by electron capture help heat the outgoing material and keep the shock wave going. It is thought that the released gravitational potential energy of full core collapse is able to be sufficiently concentrated so that a portion of the outer layer is released, but the mechanics are not completely satisfactory. In the case of Eta Carinae, the collapse is slow, asymmetric, and incomplete. It would be impossible to argue that the resulting explosion is the result of a shock wave. And even if it were, the shock wave would be resisted by the remaining mass of the two cores that have to be accelerated away from each other.
Yet, we argue that the energy production mechanism is the same in the two cases. We even argue that the same mechanism powers the gigantic bodies known as Quasars, and may indeed be responsible for many other otherwise unexplained galactic phenomena.
What mechanism is this? Ask yourself if you know of any energy production mechanism on Earth that is capable of slow, controlled energy release, rapid accidental energy release, and even explosive energy release. The answer is fission! Nuclear reactors can be operated safely as power plants, or can malfunction and destroy themselves in a Chernobyl-type accident. And small assemblies of fuel can be made into atomic bombs.
Picture a Quasar as a feedback controlled nuclear reactor, Eta Carinae as an accidental criticality power excursion, and a supernova as an implosion-type atomic bomb. All we need is a fission mechanism. But it can't be based on uranium and neutrons. It must operate on a galactic scale, and the annihilation of matter must be almost complete.
What do we propose? We propose the fission of protons by neutrinos, which we call neutrino-induced proton fission, as first suggested by Bly [3]. The end result is the almost complete annihilation of protons into energy in a form capable of explosively affecting the movement of Eta Carinae.
References
1) Robert Zimmerman, "Scoping Out The Monster Star", Astronomy, pp 38-43, February 2000.
2) Charles A. Bly contributed to this conceptual model in 1997.
3) Charles A. Bly, "Neutrino-Driven Nucleon Fission Reactors: Supernovas, Quasars, and the Big Bang", Transactions American Nuclear Society, Vol. 66, pp 529-532, 1992.