Station 3: Protostellar 'Factories' Churn Out Chemicals

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The “Mountains of Creation” (in the interstellar cloud W5) reveal collapsing cloud “cores” where complex chemicals are produced in protostellar nebulae (arrows). The Goddard-built infrared camera on Spitzer Space Telescope took this image. The star-forming region (“core”) is a hot and turbulent place where energetic radiation abounds as X-rays and ultraviolet light. This energy fuels a rich and diverse chemistry that extends the formation of complex organic molecules begun in the interstellar cloud. The legacy chemicals found in primitive Solar System materials reveal this mixed heritage.


A new protostellar disk is typically flared, as seen in this image and diagram of an edge-on disk. The new star illuminates the disk from within, and jets of material escape along the polar axes above and below. In the hot inner zone, tiny dust grains convert gases into simple organic compounds. Other reactions form carbon dioxide on cold grains in the outer regions, while ionized and neutral gases form new chemicals in regions reached by X-rays and ultraviolet light. Internal forces mix material between the inner and outer disk regions.


After a star forms, the leftover dust and gas become the protoplanetary disk. When the conditions are right, this material will eventually condense into planets and small bodies such as comets and asteroids. This icon represents the epoch when Solar System planets began to form and large-scale chemistry in the nebula ended.


DUST GRAINS KICK-START CHEMICAL REACTIONS: Dust grains in space often serve as tiny test tubes where curcial chemical reactions take place. Goddard scientists investigate these reactions using heated grains of astrophysical "smokes". Center: A tiny interplanetary dust grain collected in Earth's stratosphere.

In the hot inner region of a protostellar disk, countless tiny dust grains convert gases stuck to their surfaces into simple organic, or carbon-containing,compounds. Later reactions will convert these compounds into more complex molecules, possibly including ingredients of the “prebiotic soup” that led to life on Earth. The “cosmic cycle” of this production is illustrated above.


DUST IS CLEARED AS PLANETS FORM: The protoplanetary disk phase ends with the formation of planets and clearing of gas from the disk. Gaps appear in the disk as the planets grow, here illustrated by the giant gas planets (left). After planetary growth ended, the Solar System could have been configured with an outer disk of icy bodies and with Uranus as the outermost giant planet (above, right). Today, Neptune is outermost.

The same chemical reactions that made complex organic chemicals in the inner solar nebula can be used to convert coal into gasoline and nitrogen from the air into fertilizer here on Earth.

NASA Official: Dr. Jason Dworkin
Website Manager: Alicia Magee