Exoplanets - Guided Notes
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Jan 9, 2024
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Guided Notes – Exoplanets Name:
Leah Walker
These notes cover slides 7 - 14 of Video Lecture – Exosystems
.
For slides 7 - 14 please type or handwrite notes as you watch the video lecture and
answer the included questions.
Exoplanets:
An exoplanet, also known as an extrasolar planet, is a planet that orbits a star outside of our solar system. Since 1995, thousands of exoplanets have been discovered, and they come in different sizes, compositions, and orbits. Some are similar to Earth, while others are gas giants like Jupiter. Scientists are interested in finding exoplanets in the habitable zone of their star, where conditions are suitable for liquid water to exist on the planet's surface. This
makes it a potential candidate for supporting life.
Test Yourself: Selection Effects
Which of these would make it easier to see an exoplanet?
A)
planet is close to its star
B)
planet is far from its star
C)
planet is made of gas
D)
planet is made of rock
Your answer: planet is far from its star
Radial Velocity Method:
The Radial Velocity Method detects exoplanets by observing the Doppler shift of a star's spectrum. It relies on observing the spectra of stars for signs of "wobble" caused by the presence of planets. This method involves looking for signs of movement in a star and has a high success rate for identifying exoplanets. It allows for the direct measurement of the eccentricity of the planet's orbit, but requires a high signal-to-noise ratio spectra for precision. It is generally used to look for low-mass planets around nearby stars.
Test Yourself: RV Selection Effects
What gives the host star the biggest, most easily observed, radial velocity?
A)
a low-mass planet in a close orbit
B)
a low-mass planet in a distant orbit
C)
a high-mass planet in a close orbit
D)
a high-mass planet in a distant orbit
Your answer: a high-mass planet in a close orbit Transit Method:
The Transit Method is a technique used to find exoplanets by observing the dimming of a star's light as a planet passes in front of it. This method works because when a planet passes in front of its star, it blocks some of the star's light, causing a dip in brightness that telescopes can detect. The Transit Method has been very successful in finding exoplanets and has found more than 2,771 of the 3,526 confirmed exoplanets to date. One of the best things about Transit Photometry is that it can accurately tell us how big the planets are. When combined with the Radial Velocity method (which can tell us the planet's mass), astronomers can figure out the planet's density and what it's made of.
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Test Yourself – Transit Selection Effects
If you must observe several transit events to announce a planet candidate, which will you be able to announce soonest?
A)
a planet in a close orbit
B)
a planet in a distant orbit
C)
distance would not matter
Your answer: a planet in a close orbit
Summary of Selection Effects: