Wonders of Space

Observatory / Course Archives / ASTR 110 Fall 2019 / Ha

Neptune

Neptune is a jovian planet within our solar system that resides beyond Uranus. Jovian planets, also referred to as gas giants, are typically found in the outer regions of the solar system that lie beyond the Asteroid Belt. Being a Jovian planet, Neptune is primarily composed of Hydrogen, Helium, and Methane. Because these gas giants like Neptune are typically massive in size and thus have stronger gravitational fields, they are able to accrue a lot of gas that goes towards its composition. Jovian planets also make use of the cool temperatures to facilitate the accumulation of additional gases.

While Saturn is the planet that is most commonly known for its accentuated rings, Neptune also possesses its own rings although they are not as prominent. Neptune has five rings that we know of- Galle. Leverrier, Lassell, Arago, and Adams- that were each named after an astronomer who made an important discovery regarding the planet. This picture allows us to see Neptune's rings in detail. The planet's rings are difficult to see because they are dark and vary in density and size. Astronomers believe that Neptune's rings are young compared to the age of the planet. They also hypothesize that the rings were formed when one of Neptune's rings were destroyed.

Omega Centauri

In our vast universe, there are two types of star clusters that we have identified so far: Open and Globular. The Omega Centauri is classified as a globular star cluster. This means that the stars in this cluster are very old; in fact, the stars within this particular cluster are between ten to twelve billion years old. Globular clusters also have a lot of mass, comprised of hundreds of thousands to millions of stars, and are randomly distributed throughout the halo of a galaxy. Omega Centauri is found in the halo of the Milky Way. Looking at the image above, you may notice that there are multiple variations regarding the colors of the stars. The color differences of the stars are attributed to the fact that these stars are in different stages of stellar evolution. The majority of the stars in this cluster are yellow-white and are adult stars that are undergoing the process of hydrogen fusion. The orange stars are adult stars that are in the later stages of stellar evolution, and the red stars are red giants that have exhausted their core hydrogen supply. Although many people may guess that the bright blue stars in this image are young stars, they are actually adult stars that have ejected most of their mass and exhausted most of its hydrogen fuel, while the faint blue-white stars are white dwarfs that are nearing the end of their evolution.

Despite the fact that Omega Centauri is classified as a globular cluster, due to recent research and new facts that have come to light, astronomers suspect that Omega Centauri may be an imposter. One reason for this suspicion is that globular clusters are generally comprised of stars that are of the same age and composition. However, studies have revealed that this cluster contains different stellar populations that formed at various periods of time. Another reason astronomers think the Omega Centauri is an imposter is because of the medium-sized black hole that is located at its center. This blackhole was discovered through observations that showed the stars at the cluster's center was moving around at an unusual rate. The black hole implies that Omega Centauri is more a dwarf galaxy that was stripped of its outer stars, rather than a globular cluster.

Orion Nebula

A nebula is a cloud of dust and gas that is often the site of star formation. What's cool about nebulae is that we are able to discern what category of nebulae it fits in based on the wavelengths that it emits. The picture above, taken by NASA's Hubble Space Telescope, depicts an image of the Orion Nebula. Observing this picture, we can identify a "red" and "blue" appearance. There are two kinds of nebulae that emit these colors: Emission and Reflection nebulae. Emission nebulae have a red appearance due to the large number of excited and ionized hydrogen atoms. Reflection nebulae appear blue because particles in the nebula reflect blue light more efficiently than they do red light. From this, we can then infer that this particular nebula is both a reflection and emission nebula.

In the bright central region of this nebula is the Trapezium cluster, where four of the nebula's heftiest stars reside. Within this stellar cavern lies a multitude of young stars that are in various stages of stellar formation. The bright visible glow of the Trapezium cluster can be attributed to the ultraviolet ionizing radiation of the trapezium stars. When astronomers were studying this particular nebulae, they observed that the velocity of the trapezium stars were quite high. Scientists postulate that this may be due to a black hole, 100 times the mass of the sun, that was formed from runaway stellar collisions.