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Notes covered in Exam1 - How Do We Detect Planets Around...

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How Do We Detect Planets Around Other Suns? ASTR 2340 Spring 2010 Rupali Chandar
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Protoplanetary Disks in the Orion Nebula -- A “Protoplanetary Disk” is a rotating disk of dense gas around a young, newly formed star. -- Planets are believed to form out of these disks -- Over 100 Protoplanetary disks have now been imaged directly Planetary nurseries do exist!
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How do we Search for Planets around Other Stars? -- ‘Extra-solar’ planets, I.e. around stars other than our own sun, are too faint and small for us to image directly (for the most part). -- Instead, we have to look for the effects that a planet has on its star, using indirect techniques, such as: 1. Doppler spectral shifts produced by “wobble” of star 2. Astrometry (measuring the exact position of a star as it wobbles) 3. Photometry (Measuring the change in brightness of a star) 4. Pulsar timing
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Summary: What we have found -- ~300 planets now discovered (do not confuse with protoplanetary disks) -- Most planets detected to date are huge, Jupiter-like planets -- don’t have good enough technology yet to detect lots of earth-like planets (selection effect) -- these Jupiter-like planets live in solar systems with a very different “architecture” than our own -- these massive planets are much closes to their parent stars than Jupiter is to our Sun!
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How we find extra-solar planets • Stars are too bright to see reflected light from planets directly (using telescopes on Earth) • Unseen planet causes star to wobble as it orbits – star’s light can be Doppler shifted
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Doppler Shift Wavelength is shorter when approaching Stationary waves Wavelength is longer when receding
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Spectroscopic Binaries As 2 stars orbit each other, their spectral
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This note was uploaded on 02/21/2011 for the course ASTR 2340 taught by Professor Rupalichandar during the Spring '10 term at Toledo.

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Notes covered in Exam1 - How Do We Detect Planets Around...

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