Essay on Astronomy

Task one

Article: Imara, N., Forbes, J. C., & Weaver, J. C. (2021). Touching the Stars: Using High-resolution 3D Printing to Visualize Stellar Nurseries. The Astrophysical Journal Letters, 918(1), L3.

Topic: What are “stellar nurseries” and protostars, and what advances have been made in discovering and studying them?

The Astrophysical Journal Letters article “Touching the Stars: Using High-resolution 3D Printing to Visualize Stellar Nurseries” by Imara, Forbes, and Weaver discusses the use of high-resolution 3D printing to observe stellar nurseries and protostars. As the locations where new stars are born, vast regions of space known as molecular clouds are referred to as stellar nurseries. Cold, dense gas and dust that can become protostars when crushed by gravity make up these natal habitats. Protostars are still developing stars encircled by a disk of gas and dust, which allows planets to form around them.

The authors used high-quality 3D printing to create accurate models of stellar nurseries and protostars. These models can study the evolution and composition of extrasolar planets and moons. When data is converted to 3D printing format, models are created (Imara et al., 2021). HST and ALMA data are used for this. In this post, we’ll look at how 3D-printed models might improve research, instruction, and outreach. These models can help us comprehend and communicate star and planetary formation’s physical processes. Simulations can verify theoretical assumptions and improve understanding of protostar and stellar nursery evolution.

Task two

1. Why do nebulae near hot stars look red? Why do dust clouds near stars usually look blue?

Nebulae, interstellar clouds of gas and dust, can emit different colors of light depending on their physical state and the radiation that lights them. The gas’s prominent emission lines determine a nebula’s hue. Ionized hydrogen gas (HII regions) in nebulae near bright stars generates red light at 656.3 nanometers (nm) when hydrogen atom electrons recombine with protons. The H-alpha emission line is hydrogen’s most visible emission line. UV energy from hot stars ionizes hydrogen gas and emits the H-alpha line. The star’s dust clouds are blue because they reflect and disperse its blue light. Rayleigh scattering scatters light when dust particles are smaller than the wavelength. Blue light has a shorter wavelength than red light, thus dust particles distribute it more efficiently. Blue-red light differential scattering causes this. Dust clouds appear blue from afar.

2. Describe how the 21 cm line of hydrogen is formed why is this line such an important tool for understanding the interstellar medium?

The radio-frequency hydrogen 21 cm line is produced via the hyperfine transition of the atomic hydrogen ground state. Hydrogen atoms consist of one proton and one electron, each with two spin states—parallel or antiparallel. When an electron performs a hyperfine transition, it changes its spin state and emits or absorbs a photon at 1420.4 MHz, or 21 cm. This line helps us understand the interstellar medium (ISM) by identifying and mapping neutral hydrogen gas, its most abundant component. Neutral hydrogen produces and absorbs 21 cm line radiation depending on its motion relative to the observer. The 21 cm line’s Doppler shift can be used to compute hydrogen gas’ velocity and map its distribution in the Milky Way and other galaxies. The 21 cm line’s immunity to dust extinction, which blocks UV and optical radiation from distant stars and galaxies, is especially noteworthy. Thus, it can penetrate dense gas and dust to reveal the ISM’s kinematics and structure.

3. Give several reasons the Orion molecular cloud is such a useful “laboratory” for studying the stages of star formation.

The Orion molecular cloud is a large complex of interstellar gas and dust located in the constellation Orion, which is actively forming stars. Here are several reasons why it is a useful laboratory for studying the stages of star formation:

Proximity: One of the most researched areas for star formation is the Orion molecular cloud because of its proximity to Earth (about 1350 light-years). Astronomers may observe it closely and with a variety of telescopes and equipment thanks to its close vicinity.

High star formation rate: One of the Milky Way’s most active star formation regions is the Orion molecular cloud. Thus, this site is a great laboratory for studying star formation, from intense core collapse through planetary system creation. The Orion molecular cloud has protostars, prestellar cores, HII zones, and young stellar clusters. This collection is suitable for understanding star formation’s physical and chemical mechanisms.

Clear view: Dust-free Orion molecular cloud makes intense core collapse and protostar generation easier to see. Stars need molecular gas in the Orion molecular cloud. NH3 and CO chemical emission lines can be used to study the gas’s physical characteristics and kinematics. Hubble, Spitzer, Chandra, and ALMA have explored the Orion molecular cloud. These facilities described the area’s star generation stages.

4. Explain why we have learned a lot about star formation since the invention of detectors sensitive to infrared radiation.

Visible light is shorter than infrared radiation, which has a wavelength between 0.7 and 1 mm. Infrared radiation is essential for researching star formation because dust clouds block visible light surrounding newborn stars and protostars. Hot dust and gas during star formation generate infrared light that can be used to measure the interstellar medium’s physical state and behavior.

The invention of detectors sensitive to infrared radiation, such as bolometers and arrays of detectors, has revolutionized our understanding of star formation. Here are several reasons why:

1. Protostar detection: Infrared research can detect thermal radiation from warm dust surrounding newborn stars and protostars. Scientists have observed protostars from collapse through accretion and disk formation. Star-forming regions’ dynamics and physical characteristics can be revealed through infrared measurements of interstellar medium dust grains. Infrared spectroscopy can disclose dust grains’ chemical makeup, which can illuminate the interstellar medium’s origin.
2. Stellar populations: Low-mass stars and brown dwarfs emit faint infrared light. Astronomers may now investigate all young stars and protostars in star-forming zones, including their mass function and spatial distribution. Infrared observations can reveal the interstellar medium’s kinematics and physical properties by identifying molecular gas tracers like CO and H2O. By detecting molecular gas absorption by dust particles, infrared measurements can reveal dust distribution and characteristics. In general, infrared radiation-sensitive detectors have helped us understand star formation and the interstellar medium and research the physical and chemical processes that build and evolve stars and planets.

References

Imara, N., Forbes, J. C., & Weaver, J. C. (2021). Touching the Stars: Using High-resolution 3D Printing to Visualize Stellar Nurseries. The Astrophysical Journal Letters, 918(1), L3.