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Requirements for the Workshop on Friday.

Requirements for the Workshop on Friday. Lecture 15 - This Class – finish GR. All materials are at http://www.physics.umanitoba.ca/~english/ 2013fallphys1830/bwimaging/ GNU Image Manipulation Package (GIMP).

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Requirements for the Workshop on Friday.

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  1. Requirements for the Workshop on Friday. Lecture 15 - This Class – finish GR • All materials are at http://www.physics.umanitoba.ca/~english/2013fallphys1830/bwimaging/ • GNU Image Manipulation Package (GIMP). • You can use PhotoShop IF you are an expert and your version has “screen mode” in layers. • Run GIMP to set up your preferences before you get to class. • Black and White image jpegs – either your own or mine. • Do you need a power socket for your laptop? • Yes • No • Workshop material will be on November test.

  2. Seeing Gravity: The “law” of General Relativity • GR has 4 dimensions: 3 spatial dimensions and 1 time dimension  spacetime. • Definition: The presence of mass curves spacetime and we interpret the curved motion (i.e. orbits) of particles in curved spacetime as acceleration due to a force, i.e. gravity.

  3. GR: Gravitational Lensing • A foreground object like a galaxy (or a cluster of galaxies) bends the fabric of spacetime. • Light must travel in spacetime so it bends around the curve. • Projecting back onto the celestial sphere we see more than one image of an unresolved background galaxy (e.g. quasar).

  4. GR: Gravitational Lensing • A background galaxy will be made into arcs by the foreground lensing galaxy or cluster of galaxies. • All of the matter in the foreground galaxy (luminous and dark) bends spacetime.

  5. Seeing Gravity: • The clusters are acting as lenses. • The arcs are background galaxies. • Using GR we can determine how much matter must be in the foreground cluster in order to create the arcs. • Measuring up all the luminous emission (x-ray through radio) gives the amount of mass due to processes that produce EM radiation. • The lensing mass is much greater than the luminous mass in the cluster  Dark Matter! • (Changes to Newton’s Laws won’t make DM go away)

  6. Seeing Gravity • A single galaxy lensing a background galaxy.

  7. Seeing Gravity General Relativity is applicable to everything from the precession of the planet Mercury to your cell phone. On the shuttle (in orbit therefore accelerating) the astronauts measure time, using atomic clocks, to be moving slower than the folk in mission control  spacetime! • A single galaxy lensing a background galaxy  Dark Matter.

  8. Fill in the Blank Question: The lensing of a distant quasar is produced by ________ of a foreground galaxy. A) all the normal matter and dark matter B) only the mass of the black hole in the centre of a galaxy C) an individual star D) a supernova’s intense magnetic field

  9. Bubble Nebula – NGC 7635 Phys 1830: Lecture 15 • Goal: Explore how to construct a public outreach image. • Within each public outreach image is the struggle between scientific meaning and visual aesthetic.

  10. Colour Image-making: Stage 1 Veil Nebula • Before colourizing we need to map data values from 1 to 65536 onto a grey scale from 1 to 256. • Stretch: example of the change in the display of detail.

  11. Recall: http://hubblesite.org/gallery/ behind_the_pictures/ meaning_of_color/eagle.php Black and white images capturing light from oxygen atoms, hydrogen atoms, and sulfur atoms. Colours are assigned and the images are combined. Public outreach images are not digital snapshots.

  12. Goals for an Image: David Malin (AAO). Almost “true” colour. • Present scientific information. • Engage the viewer so they explore the topic via other avenues. • Balance these 2 goals above.

  13. Constructing Colour Images: • Selecting the order of the colours • Chromatic • Composite

  14. Constructing Colour Images: • Natural/Chromatic: e.g. galaxies • Representative/Composite: e.g. bright versions of Saturn • Enhanced/Chromatic: e.g. Eagle Nebula

  15. Constructing Colour Images: Example of Chromatic Ordering Seyfert’s Sextet: HST WFPC2 English and collaborators • Assign colours to black and white images.

  16. Constructing Colour Images: Examples Seyfert’s Sextet: HST WFPC2 English and collaborators • Combine colourized images.

  17. Constructing Colour Images: Heritage Hodge 301 Hodge 301 in the Tarantula Nebula Through Various Filters

  18. Constructing Colour Images: • Notice the width of the main part of this filter goes from roughly 470nm to 600nm. • The peak transmission is about 540 nm for the combination of the telescope and filter.

  19. Constructing Colour Images • A mathematically defined colour space developed by Commission internationale de l'éclairage (CIE) for use in studies of colour perception. • Wavelengths associated with perceived colours are labeled in blue. • HST’s 555nm filter ranges from turquoise to red! The peak is at green (540nm) or yellow green (555nm)

  20. Narrowband Filters Constructing Colour Images: Heritage Hodge 301 Hydrogen Oxygen Sulfur Hodge 301 in the Tarantula Nebula Through Various Filters

  21. Opportunity to create something different than the Hubble Heritage version. Constructing Colour Images: Heritage Hodge 301 Hodge 301 in the Tarantula Nebula Through Various Filters

  22. Constructing Colour Images: • Other colour assignments can be found at http://www.physics.umanitoba.ca/~english/viz2009/ • Many colour versions are valid!

  23. Constructing Colour Images: • Discuss with your neighbours what colours you would use for the filamentary gas exposures. Why?

  24. Constructing Colour Images: • Sometimes an imaging team will describe their colour assignments.

  25. Interaction of Light and Matter Recall HII regions are deep red through pink. The Orion Nebula David Malin • H

  26. Hickson Compact Groups (HST) Constructing Colour Images: Multiwavelength Data HST only: 3 broadband filters HST and Spitzer and GALEX HCG 31 J. English with Sarah Gallager and Jane Charlton et al.

  27. The Culture of Science has a Strong Impact These are like contour plots. To engage viewers we can use visual grammar.

  28. M82 – Hubble Heritage

  29. Visual grammar includes: • the techniques of composition • colour harmony • The effect of using visual grammar is to create an image that engages the viewer and retains their attention. It creates • spatial depth • richness in colour and detail • Communicates some of the content without need of a legend Visual Literacy

  30. This painting can be seen at: http://www.moma.org/collection/browse_results.php?object_id=79802 Visualization versus Scientific Meaning 1 V. Van Gogh

  31. NGC 2207 and IC 2163 Conventional north up and east to the left Visualization versus Scientific Meaning 1

  32. Hubble Heritage Orientation Visualization versus Scientific Meaning 1

  33. This image can be seen at: http:www.guggenheimcollection.org/site/artist_work_md_158_8.html Visualization versus Scientific Meaning 2 V. Van Gogh

  34. Composition and Colour Harmony Play a role 2. Which part of this image is cold and which part is hot? Visualization versus Scientific Meaning 2

  35. Composition and Colour Harmony Play a role 2. Which part of this image is cold and which part is hot? • The public is likely to read the central part of the nebula as: • Cool • Warm • A scientist is likely to read the central part of the nebula as: • Cool • Warm Visualization versus Scientific Meaning 2

  36. Composition and Colour Harmony Play a role 3. Which part of this image jumps forward and which part falls back? • The circle that jumps forward is: • Blue • Red Visualization versus Scientific Meaning 3

  37. Composition and Colour Harmony Play a role 3. Which part of this image jumps forward and which part falls back? Visualization versus Scientific Meaning 3

  38. Review: b) • Which image do artists consider more engaging? • Left - The displaced circle (dynamic). • Right - The centred circle (static). a)

  39. These are useful for selecting colours to make harmonious compositions. Simple Colour Wheels Based on a colour wheel by Newton, these are renditions of the same relationships.

  40. Primary Colours: • colours used in combination to make other colours. • No other colours can be mixed to create a primary. Simple Colour Wheels • Secondary Colours: • the colours generated by adding primaries together.

  41. Subtractive Colour System (CMY): • e.g. paint and ink • primaries are cyan, magenta and yellow • secondaries: • red-orange, green, blue-violet (i.e. purple) • e.g. magenta + yellow = red-orange • all 3 primaries combine together to give neutral grey (wheel on the right) Simple Colour Wheels

  42. Additive Colour System (RGB): • e.g. theatre gels and monitors (e.g. computers) • primaries are red, green, blue • secondaries are cyan, magenta, yellow • all 3 combine together to give white (wheel on the left) Simple Colour Wheels R == red is really red-orange. B == blue is really a blue-violet

  43. Complementary Colours: • across the colour wheel. • when combined they contain all 3 primaries and add to neutral grey (subtractive system) or white (additive system). •  harmony • if the colours are not directly across then you get brown •  unharmonious Simple Colour Wheels

  44. Complementary Colours: • notice that there is a relationship between the additive system and the subtractive system. • the primary in one system is the complement in the other system. • the primary in one system is a secondary colour in the other system. Simple Colour Wheels

  45. Complementary Colours o

  46. These are useful for selecting colours to make harmonious compositions. Pick your favourite colour and then its complement. • More harmonious colours: • also use black, white, and neutral grey • split the complement - make a triangle on the wheel • make a rectangle on the colour wheel Simple Colour Wheels

  47. A Recipe for Cooking Up Astronomical Images • Cooking Up Astronomy Images Online at http://astronomy.swin.edu.au/sao/guest/english/imageindex.html

  48. Next Class: Using Colour Theory See Hidden Slides to Prepare for next class.

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