Water and ammonia factories

Nov 08, 2011
The young star forming region L1157 as seen by the Spitzer Space Telescope. A new chemical study has been able explain the relative abundances of water and ammonia in this region. Credit: NASA/JPL-Caltech/UIUC

(PhysOrg.com) -- Complex molecules, including many organic species, exist in a wide range of environments in the cosmos, and are especially abundant in giant molecular clouds of gas and dust where new stars form. The rich chemistry underway in these clouds, and in the dense disks of material around young stars, creates molecules are ingredients in living systems. Astronomers use radio, millimeter, and infrared wavelength telescopes to detect the distinct spectral lines signatures of these molecules. But what determines the relative abundances of these molecules in the first place?

CfA astronomer Izaskun Jimenez-Serra and her colleagues have developed models for chemical processes that are appropriate for the conditions in astrophysical scenarios, including the earliest stages when the gas is extremely cold and just beginning to form complex species. They take into account three important factors: the on which the reactions occur before the gas evaporates from the surface, the extremely found in most sources (often less than minus 250 degrees Celsius), and the influences of shocks and radiation that develop as in the clouds form and begin to mature.

The astronomers combine their models with new observations from the Herschel , including measurements of water, formaldehyde, ammonia, and methanol in the vicinity of very young, small stars. One of the longstanding puzzles has been the relative abundance of water and ammonia in these regions, these species being two of basic building blocks for more complex molecules. Their results show that the observed differences in the abundances of these species are due primarily to the temperatures of the regions under study. Water is frozen onto grains at extremely low temperatures, for example; ammonia is destroyed when temperatures exceed about 4000 degrees Celsius. A shock generated by outflows from the new star can act to heat the dust and gas, and thus affect the temperatures. The new results represent the first time that modeling of water and ammonia from initial conditions has been successfully achieved.

Explore further: Far from home: Wayward cluster is both tiny and distant

Related Stories

Dark clouds in space

Sep 13, 2011

(PhysOrg.com) -- Infrared dark clouds (IRDCs) are dark patches in the sky seen against the continuous, bright infrared background produced by our galaxy. IRDCs are rich in molecules and relatively dense, cool ...

Water around massive young stars

Sep 16, 2010

Water is critical to human life, but also plays an important role in the life of stars and their planetary systems. As a gas, water helps to cool collapsing clouds of interstellar material so that they can ...

The rich chemistry around an evolved star

Mar 11, 2011

(PhysOrg.com) -- Over 170 molecules have been detected in space, from simple diatomic molecules like CO to complex organic molecules with over 70 atoms, like fullerene.

Recommended for you

Far from home: Wayward cluster is both tiny and distant

20 hours ago

Like the lost little puppy that wanders too far from home, astronomers have found an unusually small and distant group of stars that seems oddly out of place. The cluster, made of only a handful of stars, ...

An old-looking galaxy in a young universe

Mar 02, 2015

A team of astronomers, led by Darach Watson, from the University of Copenhagen used the Very Large Telescope's X-shooter instrument along with the Atacama Large Millimeter/submillimeter Array (ALMA) to observe ...

Giant methane storms on Uranus

Mar 02, 2015

Most of the times we have looked at Uranus, it has seemed to be a relatively calm place. Well, yes its atmosphere is the coldest place in the solar system. But, when we picture the seventh planet in our ...

Where do stars form in merging galaxies?

Mar 02, 2015

Collisions between galaxies, and even less dramatic gravitational encounters between them, are recognized as triggering star formation. Observations of luminous galaxies, powered by starbursts, are consistent ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.