The rich chemistry around an evolved star

Mar 11, 2011
A deep optical image of the carbon star IRC+10216, showing traces of its surrounding envelope. New SMA observations study the rich chemistry of the envelope, and find 442 spectral lines from over fifty molecules. Credit: Izan Leao; the Very Large Telescope

(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.

These play a critical role in the development of as they form new stars and planetary systems, and of course in the chemistry that later develops on the surfaces of planets. One of the major issues in modern astronomy is figuring out exactly where all these molecules and associated came from.

The variable star CW Leo, also known as IRC+10216, is one of the brightest objects in the sky as seen from Earth; it is about 450 light-years away. It shines mostly in the infrared (not optical) because the central star is surrounded by a dense cloud of dust and gas that it ejected in a late stage of its evolution; that dust blocks the . The material is known to be rich in carbon-bearing molecules.

CfA astronomers Nimesh Patel, Ken Young, Carl Gottlieb, Pat Thaddeus, Bob Wilson, Mark Reid, Mike McCarthy, and Eric Keto, together with five colleagues, used the (SMA) to study the spectrum of IRC+10216 across a wavelength band, in an effort to detect and characterize as many molecules in the star's envelope as possible.

The scientists report finding an amazing 442 spectral lines in their survey, more than 200 of them detected for the first time in any astronomical source. All but 149 can be identified as arising from specific molecules. In addition to measuring the strengths of the lines and the motions of the molecules responsible, the SMA survey also obtained images of the nebula around in the star in the light of each of these species. The unidentified features, for example, tend to arise from compact regions around the star and probably correspond to hotter states of the known molecules; future work is needed to confirm this conclusion. The new results provide a remarkable view of the rich chemistry around this nearby star, and help to strengthen the conclusion that many complex molecules trace their origin to the envelopes of evolved stars.

Explore further: Millisecond pulsars clearly demonstrate that pulsars are neutron stars

Related Stories

Studying a Star Before it is Born

Dec 04, 2009

(PhysOrg.com) -- The first phase of a star's formation are thought to begin deep inside a natal cloud of gas and dust. In the earliest stages, material coalesces under the influence of gravity into so-called ...

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 ...

A wealth of molecules in an extreme galaxy

Feb 21, 2011

(PhysOrg.com) -- Arp 220 is the closest galaxy to the Milly Way with an extreme luminosity, defined as being more than about 300 times that of our own galaxy. Some dramatic galaxies have values of luminosity ...

Mining for Molecules in the Milky Way

Jun 02, 2008

Scientists are using the giant Robert C. Byrd Green Bank Telescope (GBT) to go prospecting in a rich molecular cloud in our Milky Way Galaxy. They seek to discover new, complex molecules in interstellar space ...

Herschel takes a peek at the ingredients of the galaxies

Nov 27, 2009

(PhysOrg.com) -- The European Space Agency has today released spectacular new observations from the Herschel Space Observatory, including the UK-led SPIRE instrument. Spectrometers on board all three Hershel ...

Recommended for you

How small can galaxies be?

Sep 29, 2014

Yesterday I talked about just how small a star can be, so today let's explore just how small a galaxy can be. Our Milky Way galaxy is about 100,000 light years across, and contains about 200 billion stars. Th ...

The coolest stars

Sep 29, 2014

One way that stars are categorized is by temperature. Since the temperature of a star can determine its visual color, this category scheme is known as spectral type. The main categories of spectral type are ...

Simulations reveal an unusual death for ancient stars

Sep 29, 2014

(Phys.org) —Certain primordial stars—those 55,000 and 56,000 times the mass of our Sun, or solar masses—may have died unusually. In death, these objects—among the Universe's first-generation of stars—would ...

User comments : 0