Fiery hourglass star seen by Webb

Fiery hourglass star: Brilliant, colorful gases flaring outward symmetrically from a tiny bright area.
Here’s how the James Webb Space Telescope sees the newly forming star L1527. To Webb, it appears as a fiery hourglass star. Like all protostars, this one is embedded in a cloud of gas and dust that’s feeding its growth. Plus, the star itself is ejecting material and has cleared out cavities above and below itself (the boundaries of those regions glow orange and blue in this infrared view). In the upper central region, astronomers see bubble-like shapes, which they say are due to sporadic ejections, or stellar “burps” from the star. Image via NASA/ ESA/ CSA/ STScI/ J. DePasquale (STScI).

EarthSky editors posted this story, making some minor edits, using a statement from the European Space Agency.

A fiery hourglass star

Astronomers said this week (November 16, 2022) that they’ve used the Webb space telescope to catch a newly forming star, designated L1527, whose star-forming cloud makes the shape of an hourglass. They said the star itself is hidden from view within the “neck” of this hourglass shape. But, if you look closely at the image above, you can see a thin dark line, right in the middle of the “neck” of the hourglass. It’s a protoplanetary disk, in which new planets are forming. It probably looks much like our sun did from afar, 4 1/2 billion years ago.

ESA said this dark disk in the neck of the hourglass is about the size of our solar system. Within it, clumps of gas and dust particles are sticking together, making the beginnings of planets. A statement from the European Space Agency (ESA) explained:

Ultimately, this view of L1527 provides a window onto what our sun and solar system looked like in their infancy.

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More about this image

Of the larger hourglass shape, ESA also said:

Light from the protostar leaks above and below this disk, illuminating cavities within the surrounding gas and dust.

The region’s most prevalent features, the blue and orange clouds, outline cavities created as material shoots away from the protostar and collides with the surrounding matter. The colors themselves are due to layers of dust between Webb and the clouds. The blue areas are where the dust is thinnest. The thicker the layer of dust, the less blue light is able to escape, creating pockets of orange.

Webb also reveals filaments of molecular hydrogen that have been shocked as the protostar ejects material away from it. Shocks and turbulence inhibit the formation of new stars, which would otherwise form throughout the cloud. As a result, the protostar dominates the space, taking much of the material for itself.

It’s a baby star

Despite the chaos that L1527 is causing, it’s only a baby star, about 100,000 years old. Given its age and its brightness in far-infrared light, L1527 falls into the category class 0 protostar, the earliest stage of star formation. ESA said:

Protostars like these, which are still cocooned in a dark cloud of dust and gas, have a long way to go before they become fully-fledged stars. L1527 doesn’t generate its own energy through the nuclear fusion of hydrogen yet, an essential characteristic of stars. Its shape, while mostly spherical, is also unstable, taking the form of a small, hot, and puffy clump of gas somewhere between 20% and 40% of the mass of our sun.

The fiery hourglass star gathers mass, grows, and then ignites

As a protostar continues to gather mass, its core gradually compresses and gets closer to stable nuclear fusion, the process by which stars shine. The scene shown in the image at top reveals that L1527 is doing just that, ESA said:

The surrounding molecular cloud is made up of dense dust and gas that are being drawn towards the center, where the protostar resides. As the material falls in, it spirals around the center. This creates a dense disk of material, known as an accretion disk, which feeds material onto the protostar.

As it gains more mass and compresses further, the temperature of its core will rise, eventually reaching the threshold for nuclear fusion to begin.

Bottom line: Astronomers said this week they’ve used the Webb space telescope to catch a fiery hourglass nebula blasting outward from a protostar. And within the hourglass, they see an edge-on disk, where new planets are forming.

November 18, 2022

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