star formation

Anatomy of the Orion Nebula – Imaging and imagining 3-D Gas Bodies

It is easy to forget that our 2-D images are actually representations of 3-D gas bodies, that are acting according to 4-D dynamics. In day to day life, we have many clues that we can rely upon including parallax views, perspective rules, lights and shadows, and actual physical interaction that we can use to assess the nature of objects in 3-D and 3+1 space. Unfortunately many of these clues are absent or confusing in our deep space objects. In this post, we analyze a 2-D image of the Great Orion Nebula and stellar nursery including its shape and orientation in 3-D space. Along the way, we will present an understanding of the three principle gas types in deep space photography

Thermodynamic Cloud Collapse & Me vs Gravity & Grok

Since I began working on this website, I have been using AI to fetch equations, data, and history. In general, I don’t bother discussing things much with AI, because typically AI relies on authority – number of journal articles, citations, simulations, status indicators, and other non-scientific bases to form its opinions. Me, on the other hand, I take the Richard Feynman philosophy that “Science is the belief in the ignorance of experts“. If AI believes you are straying from its narrative, it tries to “correct” you and actually let you know that what you are asking for is wrong. It finds something it agrees with, and then, tries to interject that it was at least somewhat right all along. It

The Anatomy of a Stellar Nursery

Introducing the Rosette Nebula / Stellar Nursery When I first started to image stellar nurseries, I really didn’t know anything about them. I was told that stars are being born there – that is pretty awesome, but I was curious what was it about these light generating molecular clouds (MCs) that made them prolific star builders. Sure, stars are also created in turbulent dark molecular clouds, but stellar nurseries really churn out the stars at a much higher level – often creating whole open clusters of stars. Many of the stellar nurseries get very large and can even be mapped from their Halpha light signal in other galaxies. Ok, so my interest was piqued – I had to figure out

Star Nucleation Amped Up by Tidal Effects

Spiral galaxies can vary widely in the amount of stars they are generating. It is asserted that star nucleation, via the imposition of high pressure over small volumes of molecular cloud, is the rate determining step. Turbulence of molecular clouds in galaxies is greatly increased when the chaotic, but stable, spiral galactic structure is disturbed by tidal effects of nearby galaxies. In this posting, the three main galaxies of the Leo triplet are used to illustrate and link the chain of events from tidal influence to rapid star production in the galaxies we image.

More than Dust in the Wind

There is no deny that the dark nebula, LDN 534, makes an interesting target for astrophotography. It has all the earmarks of sky clouds being transformed by the wind. In fact it is likely a section of molecular cloud ripped out of the spiral arms, and being eroded by the winds of ISM. Unlike star fields that appear like foggy light that gets more disperse as concentration drops, the eroded molecular cloud seems to be much more wispy and reluctant to yield its integrity. Undoubtedly the hydrogen molecules do yield to the wind, disassociating to become atoms while the dust gets dispersed. We are lucky in this one, as a few stars make some nice blue reflections. In other cases, the eroded molecular cloud forms very coincidental shapes – included some naturally streamlined ones.

A Rotting Fish tells no tails

In this website’s second look at the Rotten Fish dark nebula, I wanted to bring home the concenpts involved in star nucleation. In case you were wondering, the answer is yes, star formation can happen in clouds not emitting Halpha light, even though we can certainly assiciate Haspha with star cluster / stellar nurseries. The answer lies in the mechanism of pressure buildup at points allowing diatomic molecular hydrogen and dust to nucleate a star. In both cases, dust provides the necessary cold temperature in addition to critical point temperature suppression. However, in the case of a dark cloud, the pressures required to nucleation is based on cloud turbulence alone, while stellar nursery clouds are aided in pressure build-up by stellar winds. It seems from images, that star formation in clouds is much more sporadic, while star clusters are more likely to be formed in stellar nurseries shining in Halpha light.

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.

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