A team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) has spotted sugar molecules in the gas surrounding a young Sun-like star. This is the first time sugar been found in space around such a star, and the discovery shows that the building blocks of life are in the right place, at the right time, to be included in planets forming around the star. Sugar is the common name for a range of small carbohydrates (molecules containing carbon, hydrogen and oxygen, typically with a hydrogen:oxygen atomic ratio of 2:1, as in water).
“In the disc of gas and dust surrounding this newly formed star, we found glycolaldehyde, which is a simple form of sugar, not much different to the sugar we put in coffee,” explains Jes Jørgensen (Niels Bohr Institute, Denmark), the lead author of the paper. “This molecule is one of the ingredients in the formation of RNA, which — like DNA, to which it is related — is one of the building blocks of life.”
Glycolaldehyde has been detected in two places in space so far — first towards the Galactic Center cloud Sgr B2, using the National Science Foundation's (NSF) 12 Meter Telescope at Kitt Peak (USA) in 2000, and with the NSF's Robert C. Byrd Green Bank Telescope (also USA) in 2004, and in the high-mass hot molecular core G31.41+0.31 using the IRAM Plateau de Bure Interferometer (France) in 2008.
“What it is really exciting about our findings is that the ALMA observations reveal that the sugar molecules are falling in towards one of the stars of the system,” says team member Cécile Favre (Aarhus University, Denmark). “The sugar molecules are not only in the right place to find their way onto a planet, but they are also going in the right direction.”
The gas and dust clouds that collapse to form new stars are extremely cold and many gases solidify as ice on the particles of dust where they then bond together and form more complex molecules. But once a star has been formed in the middle of a rotating cloud of gas and dust, it heats the inner parts of the cloud to around room temperature, evaporating the chemically complex molecules, and forming gases that emit their characteristic radiation as radio waves that can be mapped using powerful radio telescopes such as ALMA.
IRAS 16293-2422 is located around 400 light-years away, comparatively close to Earth, which makes it an excellent target for astronomers studying the molecules and chemistry around young stars. By harnessing the power of a new generation of telescopes such as ALMA, astronomers now have the opportunity to study fine details within the gas and dust clouds that are forming planetary systems.
"A big question is: how complex can these molecules become before they are incorporated into new planets? This could tell us something about how life might arise elsewhere, and ALMA observations are going to be vital to unravel this mystery,” concludes Jes Jørgensen.
The many spectacular image of the Rho Ophiuchi (oh'-fee-yu-kee) clouds at top of page highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star Rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light. The red and yellow regions shine primarily because of emission from the nebula's atomic and molecular gas. Light from nearby blue stars knocks electrons away from the gas, which then shines when the electrons recombine with the gas.
The dark regions are caused by dust grains - born in young stellar atmospheres - which effectively block light emitted behind them. * The Rho Ophiuchi star clouds, well in front of the globular cluster M4 visible above on far lower left, are even more colorful than humans can see - the clouds emits light in every wavelength band from the radio to the gamma-ray.
The image below shows the Rho Ophiuchi star-forming region in infrared light, as seen by NASA’s Wide-field Infrared Explorer (WISE). IRAS 16293-2422 is the red object in the centre of the small square. The inset image is an artist’s impression of glycolaldehyde molecules, showing glycolaldehyde’s molecular structure (C2H4O2). Carbon atoms are shown as grey, oxygen atoms as red, and hydrogen atoms as white.
In the WISE infrared image of Rho Ophiuchi, blue and cyan represent light emitted at wavelengths of 3.4 and 4.6 micrometres, which is predominantly from stars. Green and red represent light from 12 and 22 micrometres, respectively, which is mostly emitted by dust.
This research was presented in a paper “Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA”, by Jørgensen et al., to appear in Astrophysical Journal Letters.
The Daily Galaxy via ESO
Image Credit:ALMA (ESO/NAOJ/NRAO)/L. Calçada (ESO) & NASA/JPL-Caltech/WISE Team and top of page: Adam Block, KPNO Visitor Program, NOAO, AURA, NSF
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