Emission Nebula

Fueling up a New Star – Gravity vs Angular Momentum

In order to grow, a nucleated (condensed), cold star core must accumulate hydrogen as future mass and fuel before igniting to fusion and becoming a full fledged shining star. But there is a problem in the way. Just as the sun cannot accumulate planets via gravity, without some mechanism to shed angular momentum, hydrogen will just orbit the baby star and not accumulate upon it. Viscous drag both dissipates angular momentum and allows hydrogen molecules to accumulate by spiraling down to the star. Unlike a planetary orbit, in a spiral gravity, angular momentum, and viscous drag (friction) are not orthogonal to one another, allowing friction to dissipate momentum as the gravitational fall increases it. Upon arrival at the star, there remains a lot of angular momentum that still need dissipating. Compressed, hot hydrogen forms a metallic core on the star where it creates an electromagnetic magneto – a sort of electric motor. The magneto converts angular momentum into linear momentum that squirts out as jets from the poles. Both mechanisms allow hydrogen to accumulate without spinning the young protostar to death. The jets also advertise to us that star formation is going on and results in beautiful images.

The Cave Nebula and Hydrogen’s Journey

One cannot understand the creation of stars from molecular hydrogen clouds any more than one can understand the weather here on earth without reference to thermodynamics. The weather is largely driven by water in gaseous (vapour), liquid (rain, clouds) and solid (snow, ice and ice crystals) forms. Knowing the pressures and temperatures at which these physical phase states occur is fundamental for both water in its role of creating weather, and for hydrogen in its role of creating both stars and the galaxy itself. Every atom and molecule of hydrogen must undergo and piecewise continuous journey through its phase/space – there is no leaping allowed, and the conditions must exist somewhere in a system for phase transitions to occur.
In our description of galaxies, we discuss the atomic and molecular phase states of hydrogen, but here we illustrate and explain the rest of the phase/state journey that hydrogen, at least at the nucleus of a star, must undergo to enable star formation. This is a journey from molecular gas all the way to becoming a hot, molten, liquid metal.

Swirls, Eddies, and Star Nucleation in Molecular Clouds

The popular notion that stars are created by the spontaneous, adiabatic collapse of molecular clouds is challenged. Instead, a more physically realistic model of protostar nucleation through hydrogen/dust condensation is proposed here (and in other postings) on this website) as well as by many other astronomers and astrophyscists elsewhere. Thermodynamics dictate that such condensation requires relatively cold and places within the cloud enable such condensation coupled with possible dew/sublimation point elevation. The high pressures required is likely provides by turbulence – both viscous and electromagnetic as evidenced by independent simulations. We can also see that for ourselves in our images of molecular clouds.

Collapse of a Molecular Cloud in 3 waves

The standard textbooks indicate that the start or conception of a new star formation is the collapse of a molecular cloud. But my background in thermodynamics, heat/mass transfer and fluid mechanics leaves this superficial explanation ungratifying (at least to me?). This pervasive theory has already be debunked in my description of spiral galactic structure, but what should replace it? What would cause a molecular cloud or part of one to “collapse”. I have presented here, three variations of the same view of the Bernard 169 (the loopy one on the right), and Bernard 174 (shaped like a foot on the far left) – both molecular clouds in the process of “collapsing”, or as I would rather put it – condensing – towards star conception. Both B169 and 174 are dark nebulae that emit no light of their own, but rather block light from the background and reflect any starlight from stars in their proximity. There are indications, even in this dark nebula, of new star formation – can you spot them?

Narrowband Light & Filters – A Quick Overview

Using the fascinating and recently discovered Squid Nebula (Ou4) as an example, I discuss the use of narrowband filters to image emission nebula. To emit light at specific narrowbands, the right element, degree of stimulation (UV light), and even density must be present. It makes for beautiful images and reveals a lot of structure in the targets.