1 / 24

Exploring Planets Beyond: How Different Methods in Astronomy Work

Dive into the fascinating world of astronomical timing and planet discovery methods, from pulsar timing to radial velocity and the transit method. Learn about advanced spacecraft and key findings about exoplanets, stellar spectra, and the Sun's composition and behavior.

davidmarshall
Download Presentation

Exploring Planets Beyond: How Different Methods in Astronomy Work

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Pulsar Timing How it works • Pulsar sends out very regular signal • Pulsar is slightly nearer/farther from us • Pulses come slightly late/early Advantages • Very sensitive • Cheap • See low mass planets Disadvantages • Works only on pulsars (weird stars) Score = 33

  2. Other Timing How it works • There are other very regular signals from stars • Orbiting eclipsing binary stars • Pulsating subdwarf stars • Signals come slightly late/early Disadvantages • Works only in very special circumstances (rare) Advantages • Can see planets with large orbits Score = 25?

  3. Radial Velocity / Doppler Method How it works • Star moves towards and away from us • Alternating red-shift / blue shift Disadvantages • Massive planets • Small fast orbits • No observation of planet Advantages • Sensitive method Q. 60: Radial Velocity Method Score = 814

  4. Transit Method How it works • Planet blocks light from star, making it dim • Star blocks light from planet Disadvantages • Requires Luck • False Positives (requires confirmation) Advantages • Works well from space • Measure spectrum of planet • Measure atmosphere of planet Score = 2911

  5. Spacecraft for the Transit Method TESS • Operating ’18–’30? • Expect 20,000+ planets COROT • Operated from ’08–’13 Kepler • Operated ’09–’18 • Has seen sub-Earth sized planets

  6. Sub-Earth-Sized Planets from Kepler

  7. Earth-Sized Planets Are Not Uncommon

  8. Earth-Sized Planets in Habitable Zone

  9. What Have We Learned? • Many large planets – Jupiter size and greater • Planets as small as Earth and smaller • Observational bias favors finding large planets • Often find planets very close to star • Observational bias • Gas giants can live very near their stars • Orbits often highly eccentric

  10. Lessons from Extrasolar Planets? • We probably need to rethink our understanding of how stellar systems form • Planetary migration is often an important factor? • Giant planets form far away • Later move inwards • Eccentric and even retrograde planets are not rare • Planets are not uncommon • Including Earth-sized planets • Stay tuned

  11. End of Material for Test 2 Questions?

  12. The Sun Magnetic Fields and Charged Particles • Charged particles are affected by magnetic fields • They are forced to follow magnetic field lines Magnetic fields

  13. Plasmas • At ordinary temperatures, atomic nuclei attract electrons to make them neutral • At extreme temperatures, the electrons pop loose, and the electrons can run off freely • This is a plasma • Plasmas are excellent conductors • They can generate magnetic fields

  14. Atomic Spectra • Suppose you take an atom and bump the electrons up (by heating it, for example). What type of light comes out? • Spectrum consists of emission lines • Exactly which lines tells you the kind of atom, like a fingerprint

  15. Atomic Spectra • Suppose you take an atom and shine a bright white light on it. What does the spectrum of the light look like when it comes out? • Initial spectrum is continuous • Atom absorbs certain very specific frequencies • The same frequencies you saw before.

  16. Kirchoff’s Laws • Hot thick solid, liquid, or gas – Continuous spectrum • Thin gas – bright line spectrum • Thin gas with hotter thick gas behind it – dark line spectrum

  17. Kirchoff’s Laws Continuous Spectrum: Hot, thick solid, liquid, or gas Bright Line Spectrum: Hot, thin gas Dark Line Spectrum: Cooler gas in front of hot, thick solid, liquid, or gas

  18. Stellar Spectra Q. 61 Simple Stellar Spectrum Q. 62: Complicated Stellar Spectrum

  19. The Sun’s Spectrum • Hundreds of lines • Scores of Elements

  20. Composition of a Typical Star (Sun) Know These! • Hydrogen • Helium • Oxygen • Carbon • Iron • Neon • Sulfur • Nitrogen • Silicon • Etc.

  21. The Sun: Basic Facts March 1, 2019 from SDO • 109  Earth diameter • 333,000  Earth mass • Density: a bit higher than water • Rotates once every 25 days • Differential rotation

  22. The Sun: How We Know What We Know Exterior • Spectra • Temperature • Motion • Chemical Composition • Magnetic Fields • Ground-based telescopes • Eclipses • Space telescopes • Solar Wind Interior • Gravity • Magnetic Fields • Neutrinos • Helioseismology

  23. Solar Dedicated Spacecraft Solar Dynamics Observatory STEREO SOHO IRIS

  24. More Solar Dedicated Spacecraft Advanced Composition Explorer Hinode Parker Solar Probe DSCOVR

More Related