Stellar Photometry, Spectroscopy, and Astrophotography in the Introductory Astronomy Course T. Olsen & S. Tufte Lewis & Clark College
Outline I.History of the Karle Observatory II.Projects for Advanced Physics Students III.Observations for Introductory Astronomy Students
Outline I.History of the Karle Observatory II.Projects for Advanced Physics Students III.Observations for Introductory Astronomy Students
James H. Karle
Sherman Fairchild Initiative A Proposal to Reinforce Connections between Science and “Real World” Questions at Lewis & Clark College “Research is a Powerful Tool for Attracting and Retaining Students to the Sciences” “Discovery-Based Learning from the very first class”
Biology: Ecological Sampling Equipment, Microscopy Imaging Stations, and Laptop Computers Chemistry: NMR Spectrometer and UV/Visible Spectrophotometers Physics: Telescope
Moving Day
Telescope Specifications 16” Ritchey-Chretien Reflector DFM Equatorial Mount “The Sky” Planetarium Program Control SBIG ST-8XE CCD Camera Color Filter Wheel Flip Mirror: CCD/Eyepiece Self-Guiding Spectrograph
Outline I.History of the Karle Observatory II.Projects for Advanced Physics Students III.Observations for Introductory Astronomy Students
Advanced Physics Projects We Have Tried Counting the stars in a globular cluster Color Astrophotography with a CCD camera Taking the temperature of a star with color filters
How many stars are there in the Globular Cluster M15? Idea: 1.Determine the average number of “counts” (proportional to photons) from stars on the edge where you can resolve them. 2. Measure the total number of counts from the globular. Now divide by the average counts per star to find the number of stars.
Astrophotography with a CCD The CCD camera is not color sensitive. To make a color astrophotograph, we –Take separate exposures through filters: Red, Green, and Blue –Combine them into one color picture using Photoshop
M57: Ring Nebula [Blue Filter]
M57: Ring Nebula [Green Filter]
M57: Ring Nebula [Red Filter]
M57: Ring Nebula
M57: Ring Nebula (zoom)
Finding the Temperature of a Star
Finding the temperature of a star Measure the intensity of a star using the red and blue filters Calculate the measured ratio of red to blue intensity Construct a model using the Planckian distribution including the filter transmission curves and the CCD quantum efficiency to determine the implied temperature of the star.
Other Ideas: Take a sequence of pictures of Jupiter over several weeks. Track the position of the moons to get their periods and radii to verify that Kepler’s law applies. Measure spectra of stars. Use this to measure the temperature of the star from the blackbody curve, or from absorption lines. Measure the spectrum of a nebula. Identify the emission lines of hydrogen and other atoms.
Outline I.History of the Karle Observatory II.Projects for Advanced Physics Students III.Observations for Introductory Astronomy Students
Spring 2005 Evening Viewing Sessions Flip Mirror Delivered
Summer 2005 Instructor masters flip mirror & CCD Each Student takes one CCD Image Extra Credit: Three Color Image
Fall 2005 … Images of Nebulae, Clusters, Planets… Estimate the Population of a Globular Cluster Estimate the Temperature of a Star Estimate the Distance to a Star by Spectroscopic Parallax Test Keplerian Orbits of Jovian Moons