Astrochemical Reaction Models
Astrochemical Reaction Models are essential tools for understanding the complex interactions between elements in the interstellar medium, which comprises primarily hydrogen and helium gases, along with trace amounts of other elements and interstellar dust. These models simulate the conditions found in space, allowing scientists to recreate and study how these cosmic materials react with one another. As interstellar medium is often invisible and challenging to study directly, researchers use laboratory experiments and computer simulations to mimic space conditions, employing techniques like mass spectrometry and electron irradiation.
Astrochemistry, the interdisciplinary field encompassing these studies, investigates the chemical components of the universe and their evolutionary pathways. The findings from these models contribute to broader scientific questions about the origins of the universe, star and planet formation, and even the potential for life beyond Earth. By analyzing the interactions of cosmic materials, scientists can gain insights into how the building blocks of life on Earth may have been formed and delivered through meteorites from space. Consequently, Astrochemical Reaction Models play a crucial role in enhancing our understanding of the cosmos and the fundamental processes that govern it.
Astrochemical Reaction Models
FIELDS OF STUDY: Astrophysics; Theoretical Astronomy
ABSTRACT: Astrochemical reaction models include laboratory experiments and computer models that simulate the reactions and interactions of the chemical components of interstellar dust. Essentially invisible, interstellar dust exists in the dark areas of space between star systems. Astrochemistry research offers insight into questions about the fundamental role these chemical components have played in the evolution of life.
The Interstellar Medium
For thousands of years, people thought that the dark spaces between stars in the sky were empty of matter. However, astronomical research in the 1950s began to tell a different story. Astronomers discovered that these dark areas between star systems are actually filled with matter known as the interstellar medium. The vast majority of the interstellar medium—about 99 percent—consists of various forms of gas, mainly hydrogen and helium. The remaining 1 percent or so is made up of tiny, frozen particles called interstellar dust, also known as cosmic dust.
Hydrogen and helium are the two simplest chemical elements. Scientists believe that these gases were left behind in the interstellar medium after the universe was formed. Trace amounts of other gases are present in the interstellar medium, including carbon, oxygen, nitrogen, neon, argon, krypton, xenon, radon, and dimethyl ether, an organic compound. These gases may have either formed inside the cloud or originated in nearby stars. They are especially abundant in stars found in hot core regions. When these stars collapse in supernova explosions, the matter within them, including these gases, is scattered throughout the interstellar medium. Studies found that after supernova explosions, the chief gases that are released include helium and hydrogen. This may have led to the formation of the first molecules of the universe, helium hydride (HeH+).
Scientists are not sure where the frozen particles of interstellar dust originated or what specific role they play in the universe. However, they do know that the reactions and interactions of the elements that make up the interstellar medium were crucial to the formation of the universe, particularly the individual star systems and planets. Modern astronomers agree that these elements were delivered to Earth from space via meteorites, creating the conditions that would later allow life to evolve.
Studying the Interstellar Medium
Clouds of interstellar medium are invisible to the human eye. This makes them difficult to study. However, astronomers have discovered that interstellar medium can be studied using particular types of light.
When most people think of light, they think of visible light, such as that which is emitted from a lamp or the sun. However, visible light is only a small portion of the light that exists in the universe. Many different types of light exist along the electromagnetic spectrum. Not all of them are visible to the human eye.
What people call "light" is actually a form of energy that can behave as either a wave or a particle. Different types of light are classified according to their wave properties, specifically their wavelength. Visible light is somewhere in the middle of the electromagnetic spectrum. It has a longer wavelength than do ultraviolet light, x-rays, and gamma rays and a shorter wavelength than infrared, microwaves, and radio waves.
Light waves are important to astronomers because they can be used to study invisible elements of the universe. For example, when interstellar dust clouds absorb visible and ultraviolet light, the dust particles heat up and then reradiate a portion of that energy in the form of infrared. Astronomers can then use an infrared telescope to locate and study these clouds.
Scientists study interstellar medium to learn more about its composition and evolution. They believe that the interactions between the gases and dust in these molecular clouds played a key role in the evolution of life on Earth and in the formation of new stars and planetary systems.
Research Models
Studying interstellar dust in space is difficult. Therefore, scientists re-create space conditions in laboratories to learn how these elements interact. They design laboratory experiments and create innovative computer models to simulate the reactions and interactions that occur among the elements of interstellar dust. This helps them understand how these elements affect each other and the universe around them. Mass spectrometry, low-energy electron irradiation, and quartz-crystal microbalancing are some of the experimental techniques scientists use.
Research into interstellar dust is part of an interdisciplinary branch of science called astrochemistry. Astrochemistry is the study of the chemical components of the universe and how they interact with one another. It also covers interstellar clouds of gas and dust in space, the formation of protoplanetary disks, and the chemical evolution of comets. It can provide insight into important questions that have long interested scientists, such as how the universe began, how stars and planets formed, how life formed and evolved on Earth, and whether or not life might exist elsewhere in the universe.
PRINCIPAL TERMS
- astrochemistry: the interdisciplinary field that studies the chemical composition and evolution of the universe, including the chemical reactions that occur between the elements of interstellar dust.
- hot core region: an area of space where stars form.
- interstellar dust: solid particles of matter that exist in the vast regions of space between star systems.
- wavelength: the distance between two peaks of a light wave.
Bibliography
Croswell, Ken. "What the Interstellar Medium Tells Us about the Early Universe." Astronomy, Kalmbach Media, 12 Dec. 2019, astronomy.com/news/2019/12/impossible-molecules-in-space. Accessed 26 July 2021.
"The Electromagnetic Spectrum." Imagine the Universe! NASA, Mar. 2013. Web. 14 Apr. 2015.
Hermans-Killam, Linda. "Infrared Astronomy." Ask an Infrared Astronomer. California Inst. of Technology, n.d. Web. 15 Apr. 2015.
Khan, Abida. "From Cosmic Dust to the Origin of Our Solar System." Down To Earth, 13 Mar. 2019, www.downtoearth.org.in/news/science-technology/from-cosmic-dust-to-the-origin-of-our-solar-system-63551. Accessed 26 July 2021.
Marchione, Demian. The Heriot-Watt Astrochemistry Research Group. Heriot-Watt U, 26 Mar. 2014. Web. 14 Apr. 2015.
Peeters, Z., et al. "Astrochemistry of Dimethyl Ether." Astronomy & Astrophysics 445.1 (2006): 197–204. Print.
Viti, Serena, et al. "The Making of Stars ’R’ Us!" Astronomy & Geophysics 45.6 (2004): 6.22–24. Print.
Williams, David A., and Thomas W. Hartquist. "The Chemistry of Star-Forming Regions." Accounts of Chemical Research 32.4 (1999): 334–41. Print.