1 / 21

Lab 10

Astronomy 105 Laboratory. Lab 10. Lab Quiz 10. Stars within a cluster have certain properties in common. Which one of the following is not a common property?. distance age color chemical composition. The age of a star cluster is determined from the ______.

dorit
Download Presentation

Lab 10

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. Astronomy 105 Laboratory Lab 10

  2. Lab Quiz 10

  3. Stars within a cluster have certain properties in common. Which one of the following is not a common property? • distance • age • color • chemical composition

  4. The age of a star cluster is determined from the ______. • mass of the brightest giant star • main-sequence turnoff point • mass of the coolest main-sequence star in the cluster • reddest stars in the cluster

  5. How does interstellar dust affect the distance measurements to stars? • it makes them appear cooler • it makes them appear hotter • it makes them appear farther away than they actually are • it make them appear closer than they actually are

  6. Edwin Hubble discovered most galaxies show a redshift in their spectra. This indicates the galaxies are • stationary in space relative to the Milky Way. • moving away from the Milky Way. • moving toward the Milky Way. • cooler than Milky Way. • warmer than the Milky Way.

  7. The most distant galaxies have the ________ redshifts. • smallest • largest

  8. Lab 10 Hubble’s Law

  9. Edwin Hubble(1889-1953) • Measured distances to nearby galaxies using Cepheid variables • Galaxies are islands of stars • Developed a classification scheme for galaxies. • Discovered the Expansion of the Universe • Space telescope named after him!

  10. Hubble’s Law • Hubble Measured distances to nearby galaxies using Cepheid variables • Other astronomers measured galaxy velocities (redshifts) Hubble Diagram Redshifts

  11. 10 Mpc 20 Mpc 30 Mpc 40 Mpc Milky Way A C B 1400 2800 700 V = 0 700 1400 2100 km/sec Alien’s Galaxy 40 Mpc 30 Mpc 20 Mpc 10 Mpc 10 Mpc 20 Mpc Milky Way A C B 2800 1400 2100 700 V = 0 700 1400 km/sec Recessional Velocity is Proportional to Distance The Universe is Expanding!!

  12. Hubble’s Law Hubble Diagram Equation of a Straight Line y = mx + b y - recessional velocity(v) x - distance(d) m = slope = Hubble’s Constant (Ho) Hubble’s Law v = Ho d

  13. Finding a Galaxy’s Distance Hubble’s Law Hubble Diagram v = Ho d d = v / Ho To Find Distance: Measure recessional velocity (red shift) 132 Mpc

  14. Estimating the Age of the Universe 60 mph, 120 mi 60 mph, 120 mi Milky Way M100 t = 0  t = present Hubble’s Law v = Ho d

  15. Example: Ho = 60 km/s/Mpc conversion conversion t = 17 billion years

  16. Important: Do not write or mark on the Hubble Handout

  17. Sample Galaxies • Distance • images • Recessional Velocity • spectra

  18. 49.4 mm d = 15.6 Mpc S Measure to nearest 0.5 mm 1.0 mm Measuring Distance • Elliptical galaxies - same physical size (0.032 Mpc) • Virgo – known distance of 15.6 Mpc • Distances inversely proportional to angular size

  19. H line 388.8 nm 501.5 nm 112.7 nm x λobs = 388.8 nm + (112.7 nm) c (λobs – λo) L v = λo Measuring Recessional Velocity L – measure distance (mm) between the 388.8 nm and the 501.5 nm emission lines x – measure distance (mm) between the 388.8 nm line and the H line λo = 396.8 nm (laboratory wavelength of the H line) Recessional Velocity Observed Wavelength of H Line

  20. Hubble Diagram v = Ho x d Hubble Diagram x Procedure - plot data x - draw best fit line rise - find slope (Ho) x slope = rise/run x run x

  21. End

More Related