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ASTR-3040: Astrobiology. Science of Life in the Universe. Day-4. The Great Blizzard of `11. Today. § 3 HW – 6, 8, 16, 18, 38, 55, 56, 58, 60, 65 Due Thursday Feb. 3 (target) Clarksville Astronomy Club meeting 7:30pm Sears Planetarium. March 5, 2009 21:48:43 CST. •. B0. 10.

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ASTR-3040: Astrobiology


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    1. ASTR-3040: Astrobiology Science of Life in the Universe Day-4

    2. The Great Blizzard of `11

    3. Today • § 3 HW – 6, 8, 16, 18, 38, 55, 56, 58, 60, 65 • Due Thursday Feb. 3 (target) • Clarksville Astronomy Club meeting • 7:30pm Sears Planetarium

    4. March 5, 2009 21:48:43 CST

    5. B0 10 Habitable Zone • A0 Stellar Mass (Sun=1) F0 • 1 • G0 Solar System • K0 • M0 0.1 10 100 0.001 0.01 0.1 1 Stellar Radii and Planetary Orbital Semi-Major Axis (A.U.) THE HABITABLE ZONE BY STELLAR TYPES The Habitable Zone (HZ) in green is defined here (and often) as the distance from a star where liquid water is expected to exist on the planets surface (Kasting, Whitmire, and Reynolds 1993). 5

    6. Orbital Period (years) 100 0.01 0.1 1 10 10000 Solar planets pulsar planets 1000 Extrasolar ) Å Doppler 3m/s 100 Planetary Mass (M 10 1 0.1 0.01 0.1 1 10 100 Semi-major Axis (AU) PROBING THE RIGHT SEARCH SPACE The first 50 known extrasolar planets are also shown along with the planets in our solar system. The limit for planet detection using Doppler spectroscopy is shown. The range of habitable planets (0.5 to 10 MÅ) in the HZ is shown in green. 6

    7. Kepler Mission

    8. EXTENDED SOLAR NEIGHBORHOOD The stars sampled are similar to the immediate solar neighborhood. Young stellar clusters, ionized HII regions and the neutral hydrogen, HI, distribution define the arms of the Galaxy. The view is from the north galactic pole looking down onto the galactic plane 8

    9. Star Formation - Chemistry Richard Rand, University of New Mexico Todd Boroson/NOAO/AURA/NSF

    10. Elemental Abundance

    11. Ages and Chemical Composition • Ages come from main-sequence turnoff. • Stars are mostly hydrogen and helium. • Abundance of heavy elements is 0 – 3%. • Heavy elements are made in massive stars. • New heavy elements are ejected into space. • New stars form with some heavy elements. • Abundance of heavy elements records the history of star formation.

    12. Chemical Enrichment

    13. Scottish physicist James Clerk Maxwell showed mathematically in the 1860s that light must be a combination of electric and magnetic fields.

    14. In 1905 Einstein calculated the energy of a particle of light (photon) and proposed the photoelectric effect. Ephoton = hc/ photon e-

    15. Like the flavors of Ice cream – they each provide us with different information.

    16. If you pass white light through a prism, it separates into its component colors. long wavelengths IRROY G B I UV short wavelengths spectrum

    17. increasing temperature Hot objects emit light that PEAKS at shortwavelengths (blue).Cool objects emit light that PEAKS at longwavelengths (red)

    18. Try to determine EVERYTHING about how these four stars compare!! Temp, Energy output, Color, size (area)….. visible range visible range Energy Output per second Energy Output per second Object A Object B Wavelength Wavelength V I B G Y O R V I B G Y O R visible range visible range Energy Output per second Energy Output per second Object C Object D Wavelength Wavelength V I B G Y O R V I B G Y O R

    19. Atoms are mostly empty space A nucleus is about 10-15 m in size and the first electron orbits out at 10-10 m from the center of the atom – The size of the electron orbit is 100,000 times greater than the size of the nucleus

    20. Nucleus

    21. Nucleus Photons (light-waves) are emitted from an atom when an electron moves from a higher energy level to a lower energy level

    22. The type of spectrum given off depends on the objects involved Law #1 – The excited atoms within a hot dense object give off light of all colors (wavelengths) and produce a continuous spectrum -- a complete rainbow of colors (range of wavelengths) without any spectrallines.

    23. We will study three types of spectra!!! prism Hot/Dense Energy Source Continuous Spectrum

    24. The type of spectrum given off depends on the objects involved Law #2 – The excited atoms within a hot, cloud of gas give off only particular colors (wavelengths) of light and produce an emission line spectrum - a series of bright spectral lines against a dark background.

    25. We will study three types of spectra!!! prism Hot low density cloud of Gas Emission Line Spectrum

    26. The type of spectrum given off depends on the objects involved Law #3 – When the light from a hot dense object passes through a cool cloud of gas, the atoms within the cloud can absorb particular colors (wavelengths) of light and produce a absorption line spectrum - a series of dark spectral lines among the colors of the rainbow.

    27. We will study three types of spectra!!! prism Hot/Dense Energy Source Cooler low density cloud of Gas Absorption LineSpectrum

    28. The Sun’s Spectrum

    29. Effect of Metallicity