An international team of researchers using the ALMA telescope array in Chile (ALMA) managed to obtain spectacular XNUMXD images of the dark atmosphere surrounding comets ISON and Lemmon. These new observations provided important insights into the importance of comets as factories for the production of new chemicals, including intriguing organic compounds.
![The approximate position of comet ISON in our solar system at the time of Alma's observations. [Courtesy: B. Saxton (NRAO/AUI/NSF); NASA/ESA Hubble; M. Cordiner, NASA, et al.]](https://www.hayadan.org.il/images/content3/2014/08/ALMAcometsIson.jpg)
[Translation by Dr. Nachmani Moshe]
Comets store within them the oldest and most ancient materials of the solar system. Understanding the unique chemistry of these materials could lead to the discovery of extensive knowledge regarding the formation of our planet and the origin of organic compounds that serve as the building blocks of life. The high-resolution observations conducted with Alma provided a fascinating XNUMXD view of the distribution of molecules within the atmospheres of the two comets. "We have achieved a first-of-its-kind mapping of important molecules that can help us understand the nature of comets," said Martin Cordiner, an astrochemist working at NASA.
The critical 2D component obtained with Alma's observations was obtained by combining high-resolution XNUMXD images of the comets along with high-resolution spectra of important organic molecules - hydrogen cyanide (HCN), hydrogen isocyanide (HNC) and formaldehyde (HXNUMXCO). The spectrum of these substances was taken from each of the points in each of the images. The researchers were able to reveal not only the identity of the molecules but also their speeds, which provided the third dimension, namely - the depth dimension of the comet's atmosphere.
The new results revealed that the HCN gas moves out of the nucleus uniformly in all directions, while the HNC gas is concentrated in clusters and jets. These distinct behavior patterns confirmed the suggestion that HNC and H2CO molecules are indeed formed within the atmosphere of comets and they provide new evidence that the HNC molecule may be obtained from the discharge of larger molecules or organic dust.
"Understanding the composition of organic dust is important since such substances are more resistant to destruction when they enter the atmosphere of stars, and it is possible that some of them even managed to reach the Earth at the beginning of its life and were involved in the origin of life," said one of the researchers. "These observations open a window for us to this unknown component of organic materials originating from comets."
"Thus, not only does ALMA allow us to identify individual molecules in the atmosphere of comets, it also provides us with the possibility to map their locations with great precision," said one of the research partners. The observations, published a long time ago in the scientific journal Astrophysical Journal Letters, are also very important in light of the fact that comets of medium brightness, such as the two studied, contain relatively small concentrations of these critical molecules, which makes their in-depth examination from Earth using telescopes very challenging . The few comprehensive studies of this kind have been conducted on extremely bright comets, such as Hale-Bopp. The present results extend the field to comets of only intermediate luminosity. "The high sensitivity obtained as part of these studies paves the way for observations of hundreds and perhaps thousands of additional distant comets," says the lead researcher. "Our results imply that in the future it will be possible to map more complex molecules that have so far escaped the notice of scientists studying comets."
