Dust in the Orion Nebula

###Dust in the Orion Nebula
This 3D model is built from an infrared image of the Orion Nebula. It represents image brightness as elevation, translating intensity into a tactile and visual experience.

The Orion Nebula, or M42, is one of the most famous star-forming regions in the sky and can be readily seen with the naked eye as a fuzzy patch in the “sword” dangling from Orion’s belt.

###What data went into this model?
This is an observation made in infrared light by ESA’s Herschel Space Observatory at a wavelength of 250 microns. In this part of the infrared spectrum we see only the glow of dust, both warm and cold, that permeates this region.

You can learn more about the original image used for this print on the AstroPix site.

Herschel data is available at IRSA.

###What does this model show us?
In this 3D print the familiar bowl shape of the Orion Nebula, which is defined by the glow of hot gas surrounding young stars, has been supplanted by a longer ridge of dense dust that runs throughout this area.

The tallest peak corresponds to the warmest dust at the core of the visible light view, but the glowing bowl is visible only faintly as lower arcs to either side of the higher ridge.

This print helps to show us how important invisible features can be in tracing the reservoir of dense dust and gas that provides the fuel for current and future star formation in this area.

While this print can be used as a tactile experience, it was primarily developed through the lens of data visualization. Even the simple translation of intensity to elevation in a print can provide a novel opportunity to view familiar datasets differently.

It is thus important to emphasize that this model only provides a representation of the brightness in this image and in no way attempts to show the three-dimensional shape of this nebula.

###Data Processing
The print is not an exact representation of the original infrared data; several steps were take to make it work more effectively as a 3D print.

First, a single channel of Hershel data was selected that traces the full extent of dust through this region. The few point-like sources were removed to prevent sharp spikes from appearing in the print.

Next, the image was adjusted to scale down the height of the central spike of starlight relative to the outer disk. In math terms, the image was processed with an inverse hyperbolic sine (asinh) that keeps the fainter features in linear proportions while reducing the brightest features logarithmically.

The final mesh was generated in Blender, using the image data to displace a flat mesh. At this stage the mesh was further smoothed to reduce sharp features.