A small, dense cloud of gas and dust called CB 130-3 blots out the center of this image from the NASA/ESA Hubble Space Telescope.

Hubble sees a dense cloud of gas and dust on the verge of becoming a star

The process of star birth begins in a veil of gas and dust. The Hubble Space Telescope (HST) excels at showing detailed views of these star clusters as there is still much to learn about them. His latest image shows an object dubbed the “dense core,” which may already contain a stellar embryo.

From HST’s point of view, we see the outside of the creche – a region called CB130-3. This dense core lives up to its name; it is so thick that we cannot see the middle. But it gives us a glimpse into the complexity of the star-making machinery.

This cloud of gas and dust and its hidden star seed reside in a filament of gas and dust pointing toward the constellation of Serpent. It is located in an area called the Aquila Rift and is about 650 light-years from us. This location and other locations in the galaxy where nebulae form stars are of great interest to astronomers eager to understand all aspects of star formation. It has previously been observed at radio and infrared wavelengths, as well as in optical observations.

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CB130-3 resides in a filament of the large rift that extends through Aquila and Serpens. In this image, it is to the right of center in the thick dust clouds that create the rift. Courtesy of NASA.

Dense cores form baby stars

So what happens in star formation and what role does the dense core play? Starbirth is long and these cores are only part of the process. The first part begins long before cores appear. First we need a cloud of gas and dust called a “nebula”. Then it needs some external influences. Perhaps a passing star will roll up the nebula. Or a nearby supermassive star dies in a supernova explosion. Both processes send shock waves through the cloud. Whatever the momentum, these tremors fragment the cloud into smaller clumps and push down on them to form the dense cores.

In a dense core, material swirls and falls into the center. It basically accumulates gas and dust in a concentrated area. At the same time, pressures and temperatures rise. When enough material comes together, a prototype is created. That happens maybe a thousand years or more later, depending on the mass of the material. The protostar will continue to accumulate more gas and dust for several hundred thousand years.

The entire protostar phase can last about half a billion years (depending on the mass of the eventual star). Eventually, the temperatures and pressures become so high that the core of the protostar initiates nuclear fusion. Again, it could take up to ten million years for this to happen, depending on the final mass of the newborn star. But when that nuclear fusion begins, that’s when the star is born. What began as a “seed” in a dense core of gas and dust is now a full-fledged star.

Hubble’s view of the gas and dust cloud

CB130-3 is one of many of these dense cores that astronomers watch to understand the fine details of star formation. Although obscured by the thick natal cloud, this dense core already contains an embryonic star. It won’t be long (in cosmic time) before this hot young object erupts as a newborn star like the Sun.

Objects like this have interesting chemical properties. They are a so-called “carbon-chain rich” dense core. The molecules it contains are particularly useful for tracing the chemistry of thick clouds of gas and dust in which stars form. Astronomers see them as important tracers of reactive organic materials in star-forming regions. They’re also using them to track down chemical elements in protoplanetary disks, particularly complex organics, that could eventually influence the emergence of life.

To study CB130-3, astronomers used HST’s Wide Field Camera 3 to inspect the cloud surrounding the dense core. It varies in thickness, ranging from a transparent veil at the object’s edges to an almost impermeable shell of gas and dust at its center. Light from stars in the background appears reddened as it passes through the cloud. This color shift helps astronomers understand the density of different parts of the cloud that will unleash new stars into the galaxy.

Hubble views a billowing cosmic cloud
Detection of two carbon chain rich nuclei: CB130-34 and L673-SMM4.

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