Text of GEARS Workshop Wednesday Imaging Day And Fusion 2012
GEARS Workshop Wednesday Imaging Day And Fusion 2012
Warm Up Online and paper evaluation Please use what is in your own brain only.
Overview Slides Introduction to imaging Ds9 introduction and spectral line identification Atmospheric transparency Fusion and formation of the elements
Images Learn digital image basics and false color meaning Learn a new software Duplicate a press release Identify some elements in some supernova Make your color supernova image Compare your color image to the press release! Get data from other observations
Digital Image Basics More pixels good? What is false color? Why do we need false color?
Ds9 First open image and play with software (use instructions online) File: Open (you cant open the files by double clicking on them) Navigate to My Computer Navigate to E: (or the name of your thumb drive) Navigate to GEARS directory Navigate to Data Look for file
ds9 Make a press release Get an X-ray image of galaxy cluster in sky Get the same part of sky in visible light Match up the coordinates so the 2 images are lined up Try to match color scheme of press release
Hydra Composite including radio http://chandra.harvard.edu/photo/2009/hydr a/ http://chandra.harvard.edu/photo/2009/hydr a/
Right Before Lunch Sharing http://chandra.harvard.edu/edu/formal/index.html http://chandra.harvard.edu/edu/formal/index.html Other resources
Atmospheric Transparency Lab there is a student worksheet for this but no instructions What materials transmit which types of radiation (aka light the tool of the astronomer)? Which materials block or shield radiation?
Lab Instructions Find out what materials allow light to pass through and be detected Note whether the material was a shield or a transmitter See the power point for stations
Discuss the Lecture Tutorial You did it last night, right? Pages 49-51. Go through 1 3 and 4c. Reflect back to Tuesday NASA Great Observatories. Which had to be in space?
Why do you need telescopes in space? Brainstorm Metacognate what do you think your students might think.
Is it distance?
Common misconception. distance
Example assessment Which of the two proposals would you choose to fund? Project Rho: A UV wavelength telescope, placed high atop Mauna Kea at 14,000 ft above sea level, which will be used to look at distant galaxies? Project Sigma: A visible wavelength telescope, place on a satellite in orbit around Earth, which will used to observe a pair of binary stars located in the constellation Ursa Major?
Can you do the UV project effectively from ground? Why or why not? Is it cost effective to do visible astronomy from space? Especially for simple stellar observations. Why send satellites in space to do visible observations?
Chandra Chandra telescope collected Xray light Not just how many photons arrived at satellite But also time of arrival (good for short lived phenomena like gamma ray bursts) Also the energy of the photons so can identify the atomic electronic transition (think fingerprint from Monday)
Make your own 3 color diagram That means something
Concepts Astronomers make 3 color diagrams to represent 3 pieces of information visually. For example, 3 different emission line features. Spectral lines are like fingerprints, they are unique to the element or molecule that emitted (or absorbed) them due to the unique electronic energy levels in each. Type Ia and Type II supernova remnants may appear similar in size and shape but have different spectral signatures due to the different progenitors.
Supernova instructions Open ds9 Open chandraed virtual observatory Open image assigned. (115 or 126) Make a spectrum Identify 3-5 strong lines using database summarize the two types
Do if time/interest Make 3 energy cuts or filters Make 3 color image Compare your result to the press release (look for 2007 or later) energy cuts and color choices
Spectral Line ID in X-ray http://www.atomdb.org Web Guide Check your units carefully
Complexities in Real Data Roman numeral notation = ionization notation we teach minus 1 Which element/transition is it? How do we know if it is Sulfur versus Fe XX? Verification with other lines is best Most abundant in universe is indicated in chart Do I use the EXACT wavelength? What is the material is moving towards or away from us? May be Doppler Shifted
Supernova Remnants G292.0+1.8 & Tycho (left) Saw from spectra that they werent the same type of object
Tycho's Supernova Remnant Tycho's observations In the year 1572, the Danish astronomer Tycho Brahe observed and studied the sudden appearance of a bright "new star" in the direction of the constellation Cassiopeia. Now known as Tycho's supernova remnant, the event created a sensation in Tycho's time because until then stars were thought to be unchanging. Tycho's observations of this event marked the beginning of the study of astronomy as a science. This object is a Type Ia event - the thermonuclear destruction of a white dwarf. Information about this object is located at http://chandra.harvard.edu/press/05_releases/press_092205.html SNR G292 SNR G292.0+1.8 The Type II core collapse of a massive star that produced this supernova remnant ~1600 years ago is located in the direction of the constellation Centaurus. SNR G292.0+1.8 is interesting because it is one of only three oxygen-rich remnants and one of the primary sources of the heavy elements necessary to form planets and people. Although considered a "textbook" case of a supernova remnant, the intricate structure shown here reveals a few surprises. Information about this object is located at http://chandra.harvard.edu/photo/2007/g292/
The astronomy of Supernova Two types of starting points Lead to explosions Leading to remnants like you just saw But with different compositions Type 1a mass transfer Type 2 (II) high mass
Low Mass vs High Mass Progenitor
Tycho Type Ia http://hubblesite.org/newscenter/archive/rel eases/2004/34/ http://hubblesite.org/newscenter/archive/rel eases/2004/34/
Core Collapse (on right)
Spectral Line ID in X-ray http://www.atomdb.org Need to remember/know that Fe XX means Fe+19 (19 times ionized iron) HI = neutral hydrogen HII = singly ionized hydrogen
Different spectra Due to different progenitors original stars that exploded were composed of different things In one a white dwarf made of He or C with material primarily H explodes In other Fe and others smooshing into one another
Differences Type Ia: Strong Si, S, Ar, Ca, Fe Weak O, Ne, Mg Type II reverse Complications the lines are not all alone but there is a continuous emission signature at all colors! (not blackbody though) Best way to deal with spectra is to account for the continuum using a model see http://chandra.harvard.edu/edu/formal/ X-ray Spectroscopy and Supernova Remnants lab online.http://chandra.harvard.edu/edu/formal/
Research your students can do! http://cmarchesin.blogspot.com/2009/12/g29 2018-keplers-supernova-remnant.html http://cmarchesin.blogspot.com/2009/12/g29 2018-keplers-supernova-remnant.html Study with Chandra data comparing shapes of remnants Type Ia symmetric, Type II not This study was on only 17 objects your students could do more and see if trend holds How define symmetric?? Could be a discussion all by itself.
How to get data By Obs ID from list You saw obsids in press release images If Obs ID is not in list you can still get the image go to middle area where there is text and use search feature there.
Suppose the universe contained only low-mass stars. Would elements heavier than carbon exist? a.Yes, all stars create heavier elements than carbon when they become a supernova. b.Yes, but there would be far fewer heavier elements because high-mass stars form elements like iron far more prolifically than low-mass stars. c.No, the core temperatures of low-mass stars are too low to fuse other nuclei to carbon, so it would be the heaviest element. d.No, heavy elements created at the cores of low-mass stars would be locked away for billions of years. e.No, fission reactions would break down all elements heavier than carbon.
Elements in us Most of the heavy elements (everything except hydroge