Astro2110 – The Solar System

In this blog post, I’m going to be discussing more of what we learned from Unit 4, specifically about the Doppler method. As we all now know, the Doppler method is a critical tool for detecting extrasolar planets. It searches for a star’s orbital movement around a center of mass by looking for changing Doppler shifts in its spectrum. Alternating blueshifts and redshifts indicate orbital motion around the center of mass. Doppler data allows us to determine a planet’s approximate max because a more massive planet has a greater gravitational effect on the star and then causes the star to move at higher speeds around the center of mass. Typically, once a potential exoplanet is detected using the Doppler method, it requires confirmation using other techniques, such as the transit method (detecting the dimming of a star as a planet passes in front of it) or direct imaging (capturing the light from the planet itself).

Now that we’ve refreshed on the principles of the Doppler method, let’s look at some examples of how it’s been used in the past to discover extrasolar planets. In the early 1990s, scientists started used the Doppler method to search for extrasolar planets when technology started advancing to detect the subtle changes in stars’ spectra caused by the gravitational tugs of orbiting planets. They studied 51 Pegasi, a Sun-like star about 50 light years away from Earth, which is in the constellation Pegasus. It was fairly convenient since it is relatively close and bright. Michel Mayor and Didier Queloz, two Swiss astronomers, used the Elodie spectrograph in France to observe 51 Pegasi. After studying it for several months, they detected the alternating blue and red shifts, which indicated that the star was moving towards and away from earth due to the gravitational influence of an orbiting planet. By analyzing the magnitude of the Doppler shifts, they could conclude that it was a planet orbiting the star. However, it surprised them that the planet was half the mass of Jupiter but orbited so close to the star, with an orbit of roughly four days. 

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In this blog, I’m going to be discussing all things thermophiles!

Thermophiles are organisms that are found in really hot temperatures (60 degrees Celsius – 140 degrees Celsius). Found these organisms aren’t simply found there… they thrive there! Thermophiles typically inhabit a variety of extreme ecological sites, usually hot springs like in Yellowstone National Park or in hydrothermal vents under the deep sea. They can also be found in tectonically active fault lines of the earth, volcanic sites, or decomposition sites like compost piles. One example of a thermophile is a Bacillus stearothermophilus. This type of bacterium is rod-shaped, belongs to the division Firmicutes (which plays a significant role in the relationship between gut bacteria and human health), and causes spoilage in food products. 

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The reason these organisms can survive under these extreme conditions is due to a variety of factors. For starters, their cell membrane is made of a very fatty material that is highly temperature dependent and exhibits phase transition upon temperature condition. Therefore, the membrane permeability and growth of its body is controlled by the environmental temperature shifts. Additionally, the linkages that form the cell membrane are branded in a structure that enhances thermal stability that helps the bacteria survive in harsh conditions. The bacterium also have higher amounts of charged amino acids in their surface proteins that form intermolecular bridges, which provides further stability. 

There are two types of thermophiles: obligate thermophiles and facultative thermophiles. Obligates need high temperatures to grow and thrive in their environments, while facultative thermophiles can thrive at high temperatures as well as lower ones.

Thermophiles play a role in our environment for a few reasons. They can help in the immobilization of heavy metals in the soil and can also be helpful in the degradation of reactive textiles. They can also help convert biomass to biofuels in various habitats/regions.