Red Rectangle Nebula, Seismic Waves

The Red Rectangle Nebula (HD 44179) is the location for the largest recorded extraterrestrial organic molecules. These molecules are known as polycyclic aromatic hydrocarbons, or PAHs. Specifically, anthracene (C14H10, linear arrangement of 3 benzene rings) and pyrene (C16H10, condensed arrangement of 4 benzene rings) have been found through UV spectroscopy. Anthracene is commonly used in wood preservatives and insecticides. Pyrene is commonly used to make certain dyes.




Klazomania refers to compulsive shouting.

There exists two main types of seismic wave: primary waves and secondary (or shear) waves. The former is a longitudinal wave, able to compress and tense the medium in which it goes through. Since it can manipulate volume, P-waves can travel through liquids or solids. Because of this, P-waves can be felt halfway around the world from the epicenter of the earthquake, traveling through the solid mantle and the molten outer core. However, there are regions on the earth (104-140 degrees south from the epicenter) where P-waves cannot be detected because the liquid outer core slows down and refracts the P-waves. P-waves cause the least damage, but it is the first seismic wave felt. Secondary waves are second to be felt, hence the name. It is also aptly known as shear waves, for they are transverse waves that cause most of the destruction in earthquakes. Being a transverse wave means that it can manipulate the shape of the medium in which it travels through. It can only travel through a solid medium, so S-waves cannot pass through the outer liquid core. This creates an S-wave shadow zone (105-180 degrees south of epicenter). There are two special types of S-waves: SH-waves and SV-waves, the H and V representing "horizontal" and "vertical" respectively. The former is also known as a Love wave, eponymic for A.E.H. Love. Love waves are both transverse and longitudinal, for they are essentially polarized S-waves moving horizontal to the surface, moving from side to side. SV-waves move perpendicular to the surface, causing the surface to move up and down.
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