Star Parthenogenesis in Molecular Clouds – Soul Nebula in Narrowband
Televue 127is; AP 1100GTO AE
QHY 600M, - Baader 6.5 nm narrowband and RGB filters.
H,O,S: (56,33,53 x 150s, Bin 1, Gain 26)
R,G,B: (18,17,24 x 150s, Bin 1, Gain 26)
Total integration time = 30.8 hrs (Sep 4-7,9,12,15,16, 2024) Maple Bay, BC
While finding star formations in dark nebula, such as in the Rotten Fish is both fun and fruitful, if an astrophotographer desires much more activity and excitement, it is to Ha emission nebula that he/she should turn. For example, in my Rotten Fish image, SIMBAD identifies less than 10 actual or potential young stellar objects. Albeit about 8 times larger (and more distant), SIMBAD identifies more than 2200 young stellar objects in this image of the Ha emitting Soul Nebula. What is common in both, however, is a degree of chaotic turbulence in the molecular clouds that seems to go hand in hand with protostar nucleation and star formation.
New protostar nucleation is a result of inertial, viscous, supersonic, dispersive, chemical, coulombic and magnetic forces acting in a chaotic manner under non-linear dynamic conditions. The rate of protostar nucleation is most likely proportional to the energy being externally added to, and dispersed within, the cloud itself. The energy is partly expended by doing work to compress hydrogen and dust, albeit stochastically, to the conditions for star nucleation. Protostar formation is slow and low in a dark nebula where the sources of mechanical and electromagnetic energy are smaller (passing ISM, and distant stars).
In contrast, once a star is born and begins fusion within a molecular cloud, it can bombard the cloud around it with UV radiation and strong stellar winds created significantly more turbulence and Lorenzian style chaotic bifurcations to nucleate more protostars at a greater rate. In this way, once a parent star is formed, its nuclear fusion originating energy can be put to work to compress and circulate the cloud further to create additional stars through multiple generations until the cloud itself is either consumed and/or scattered.
Likely the most visually apparent way that newborn stars influence the cloud around it, is to bombard it with UV radiation that disassociates hydrogen molecules and ionizes many of the elements that get in the UV light pathway. These ions then re-accumulate electrons and in returning to their ground energy state, emit narrowband signals, a few of which occur in the visible frequency range. Most significant of which for our image, is the red-orange-yellow Halpha colours that essentially light up the surfaces of the nebula that face the star.
A second way that newborn stars effect the cloud is to push the cloud away from it. Pressure exerted on the face of clouds – both from stellar winds and radiation momentum - will increase the density of the cloud at its face while pushing the molecular cloud back away from the radiating star. In this image, two sets of clusters in the central purple regions of the nebula are pushing a ring of nebulosity outwards away from the young stars. This ring shape to the emission nebula, encircling an open cluster of new stars is quite characteristic of many star forming area.
In an accompanying frame, I have included an image of my “bathroom sink” emission nebula simulator. The radial flow of light and material from the new star(s) is represented using water that falls from the tap and radially flows outward from the impact point. The molecular cloud is also represented by water attempting to reach the drain, while competitively being kept at bay by the “stellar wind”. Water, being an incompressible fluid, gathers as a thickness column above the sink and represents the density variation that would result in a compressible molecular cloud. While the “solar radiation” pushes the “cloud front” away from its source, eddies are still apparent diffusion the energy in the “cloud” well away from the impact front. The “cloud” can be seen to get closer to the “star” when shielded by a larger mass.
Unlike the simulator, there is no drain for a real molecular cloud so the cloud simple regresses further from the star. Less dense portions of the cloud offer more inertial displacement resistance and as a result, the displacement becomes uneven, leaving mountains and valleys in the front opposing the stellar winds. The most resistant to displacement are any locations in the molecular cloud where the densities have reached conditions where protostar nucleations are possible. Furthermore, these dense gas and dust concentrations protect portions of the cloud in the star’s shadow, resulting in pillars / fingers / elephant trunks sticking out from the cloud front that we are fond of imaging. In other locations, dense globules form where stellar winds and radiation neck off high density regions from the bulk of the molecular cloud. Quite often, new stars are coming to life inside these pillars and globues.
What is less visible to us and our images, however, is the energy supplied to the molecular cloud behind the emission front, as well as acutely in the pillars and globules. This energy drives the complex, chaotic, non-linear, turbulent dynamics that create elevated density/pressure high density regions that then result in additional protostar nucleation. Inside, the cloud is kept cold by dust shielding, but coulombic, magnetic, viscous, and inertial forces are readily transmitted to increase the rate of star formation and initiate new stars. Thus, a new star, emerging from a dark nebula can parent additional stars and even clusters of stars as appear in this image.
In this explanation of the image, I do not want to underplay the role of gravity in the creation of stars. Of course, once a protostar is nucleated and grown to a size where, under its own mass additional hydrogen (and other stuff) will be attracted upon it, it eventually form the overwhelming majority of a new star. It is just that, gravity accumulation will generate too much heat causing self destruction if it occurs too early. Non-linear dynamics provides a more isothermal explanation as to how stars can emerge from the chaos.
For further reading, I high recommend two books: James Gleick: “Chaos, Making a New Science” – a very readable minimal-math description and E. Atlee Jackson “Perspectives on nonlinear dynamics” – with likely more interest to physicists and mathematicians. In applying non-linear dynamics principles, however, one has to give up the hope of forecasting the entire future based on knowing all of the current state variables of the components of a system, (but I think quantum mechanics does this as well). Like the “butterfly effect”, or the “three body problem” it also places limitations on what numerical simulation can tell us, and what needs to be modelled more empirically.