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Astronomy. Vocabulary. Spectrograph – device that breaks up the incoming light into colors and takes a picture of that spectrum Galaxy – a cluster of stars Universe – space and everything in it Light year – distance light travels in one year (300,000km per sec. or
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Vocabulary Spectrograph – device that breaks up the incoming light into colors and takes a picture of that spectrum Galaxy – a cluster of stars Universe – space and everything in it Light year – distance light travels in one year (300,000km per sec. or 9.5 million million km per yr.) Parallax – the way an object appears to change depending on the place from which you are viewing it Apparent magnitude – brightness of a star as if viewing it from Earth Absolute magnitude – brightness of a star as if it were a standard distance from Earth
California Arecibo Radio Telescopes
Spectrograph Takes in light and breaks it down into a spectrum that the astronomer can use to determine the chemical composition and temperature of a star. Each element absorbs light at different wavelengths which appears as a black line on a spectrum. Each chemical has a unique set of lines. The amount of energy each element absorbs depends on the temperature of the star. By comparing the spectrum of a star to the known spectrum at certain temperatures the astronomer can infer how hot the star is burning.
Lab 13 Flame Test Question: What can the color an element burns tell an astronomer about a star? Hypothesis: Materials: goggles apron Bunsen burner tongs copper sulfate calcium chloride sodium chloride potassium chloride strontium chloride nichrome wire spectrograph Procedure: 1. Observe all safety precautions while completing this lab. Lab aprons are to be worn at ALL times. Goggles will be worn by the person burning the chemical. When not looking through the spectrograph all others will wear goggles. 2. Be sure the nichrome wire is completely cleaned before burning the next chemical. Wash the wire under the faucet and then burn it in the flame making sure it clean. 3. Once the burner is lit, place the wire loop in chemical A. Then place the loop in the flame. Observe the color of the flame. Have one person in the group observe the colored flame through the spectrograph to see if they can see the lines produced by that chemical.
4. Record the color of the flame in the data table. 5. Repeat step 3 for each chemical you have been given. 6. Once all the chemicals have been burned you will then need to check on the board to determine which chemical is which based on the color of the flame. Results: Conclusion:
Measuring Stars Distance Are billions of galaxies in the universe Galaxies are very far apart – most of the universe is empty space Our galaxy is the Milky Way – closest galaxy to us is the Andromeda Galaxy Because of the great distances in space astronomers use the unit of the light year to indicate distance In order to measure a stars distance use parallax by measuring star when Earth is on one side of the sun and then again 6 months later when Earth is on the other side of the sun The amount the star appears to have moved is measured and used to calculate the star’s distance This is only good for stars less than 1000 light years from Earth
Classifying Stars Use size, temperature, and brightness to classify stars Size: all appear to be the same in the night sky can be giant stars or supergiant others may be white dwarfs or neutron stars these are smaller than our sun Color and Temperature: color reveals temperature coolest stars look reddish some can be white or blue-white which is the hottest Brightness: is the amount of light given off depends on size and temperature absolute magnitude is determined by apparent magnitude and distance from Earth
Hertzsprung-Russell Diagram Diagram used to plot temperature and brightness of stars When plotted - patterns formed Compiled by Ejnar Hertzsprung from Denmark and Henry Norris Russell from the US
Vocabulary Pulsar- pulsating radio source Nebula – lg. amount of gas and dust spread out in a large volume Protostar – earliest stage of a star’s life White dwarf – blue-white core of a left over star Supernova – explosion of a giant or supergiant star Neutron star – star formed from material left from a supernova Black hole – left from a massive star, mass may be 5 times that of the sun packed in a space 30km in diameter Quasar – object very far and very bright Binary star – a 2 star system Eclipsing binary – system in which one star blocks the light from the second star
Quasars Discovered in the 1960’s Are unusual – are very far away, very bright Are thought to be distant galaxies with a black hole in the middle news.bbc.co.uk
Star Systems Can have double star system Considered a binary star system If one blocks light from another is called an eclipsing binary An X-ray image of the Sirius star system located 8.6 light years from Earth. chandra.harvard.edu
Can also have a triple star system www.jpl.nasa.gov/.../newplanets/pia03521-250.jpg
Galaxies www.adg.us www.windows.ucar.edu Have spiral galaxies
Elliptical Galaxies This dwarf elliptical galaxy is is being ripped by tidal forces into long streams of stars that will eventually be merged into the Milky Way (more from IACand Astronomy Picture of the Day).
Irregular Galaxies NGC 1569 is a dwarf irregular galaxy that gave birth to thousands of new stars about 25 million years ago. stardate.org/.../galaxies/NGC-1569_220x220.jpg
History and Future To study future need to look at present Are able to tell that only a few galaxies are moving toward ours, others moving away Present theory believes was enormous explosion 10 to 13 billion years ago – referred to as “Big Bang” Big Bang began formation of universe – everything began forming at that time About 5 billion yrs ago our solar system began to form – matter was pulled into center by gravity to form sun when nuclear fusion began Planets began to form from gas and dust – both inner and outer ones Beyond Pluto is lg. cloud of ice and other substances – is likely source of comets
So, what happens next: Have several theories – universe will keep expanding and objects will get farther apart at some point the universe will begin coming back together until everything is compacted back into a lg. mass similar to original Many questions still unanswered ?
