Undergraduate Academics
Dennison Mural - Meanwhile, More Light
The Dennison lobby window installation, Meanwhile, More Light, was created by Professor of Art & Design Jim Cogswell, in honor of the Winter 2009 Theme Semester, The Universe: Yours to Discover, celebrating the International Year of Astronomy 2009. The Dennison Building is located at 500 Church St. in Ann Arbor, Michigan, and is home to the University of Michigan Department of Astronomy.
Meanwhile, More Light
2008, vinyl on glass
approximate dimensions: 11 by 150 feet
This mural responds to an array of scientific images based on astronomical research, with special focus on the work of U-M astronomers carried out within this building. It highlights my own interests as an artist while representing a small sample of the creative ways in which astronomers explore the universe, using both calculation and instrumentation to detect and study wavelengths of light. It hovers on the glass wall of a public space, on the threshold between here and there, shaped to predetermined architectural structures but open to the changing face of skies and seasons. It condenses a concatenation of thoughts about light and motion by responding to changing ambient light, the movement of viewers past the reflective windows, and the chance juxtapositions of overlapping planes of vision that seeing them demands. Floating between the reflected world and the view beyond, its flat planes of brilliant color aspire to evoke the intellectual vitality and breathtaking wonder of our search for knowledge about the cosmos.
- Jim Cogswell
Click on any image thumbnail below for the full size version.
Elements of the mural from left to right
Molecular cloud simulation
Stars form in dense clouds of molecular hydrogen, mainly concentrated in the spiral arms of galaxies like the Milky Way. These clouds are formed by colliding gas streams over several million years, until they start to collapse under their own weight and star formation begins. A computer model of this process, generated by U-M Astronomer Dr. Fabian Heitsch, shows colliding streams that have swept up a massive cloud at the center. The cloud begins to fragment, and gravity leads to the formation of stars in the densest regions. Such simulations help us understand the highly complex physics controlling star formation in our Galaxy.
Constellations of the Zodiac
Since ancient times, the constellations have played a central role in human society. Their movement across the sky was important for agriculture, navigation, and religious activity. Modern astronomers still use the constellations as a map of the sky. The 12 constellations of the zodiac trace the Sun’s path throughout year. The representations here show the constellations Virgo, Leo, Cancer, Gemini and Taurus, drawing on the 17th century Uranographia star atlas by Johannes Hevelius (1611-1687). Hevelius depicted the celestial sphere from the outside looking in, so they are mirror images of how they appear from Earth. Most of the stars in a constellation are physically unrelated. The Uranographia engravings were digitized by the Space Telescope Science Institute and U.S. Naval Observatory.
The Michigan Infrared Combiner
An extrasolar planet is a planet orbiting around another star that is not the Sun. The first extrasolar planet was discovered in 1995. Since then, astronomers have discovered over 300. Studying these planets and how they form requires cutting-edge instrumentation, like the Michigan Infrared Combiner (MIRC), designed by U-M Professor John Monnier and his team. By simultaneously combining infrared light beams from six telescopes, this instrument can see extraordinarily fine detail, like the innermost regions around nearby stars that are still building up their planets.
Feynmann Diagram
This element represents a Feynmann Diagram representing electron-positron annihilation, which is another common gamma-ray production mechanism.
The Gamma-ray Milky Way
Our Milky Way Galaxy emits light in all wavelengths of the electromagnetic spectrum. Gamma- rays are the most energetic form of light, which are seen in this view of the Milky Way by NASA’s Compton Gamma-Ray Observatory. At these extreme energies, most cosmic gamma- rays originate in collisions between energetic particles and hydrogen nuclei in interstellar clouds. The most intense gamma-ray emission originates from energetic phenomena around the supermassive black hole at the Milky Way’s center, and neutron stars.
Star cluster NGC 1850
Stars form in clusters consisting of several hundred to millions of stars. The stars in an individual cluster form together, at almost the same time. As long as the stars remain gravitationally bound to each other, they will remain together as a cluster. As a massive cluster ages and travels through its host galaxy, stars are lost via tidal interactions with other massive objects, and by their own finite lifetimes. Eventually, the entire cluster will dissolve, though this may take as long as the age of the Universe. However, small clusters may dissolve shortly after they form, if they are not gravitationally bound.
The equation derived by U-M Professor Sally Oey describes the expected mass of the most massive star in a given cluster of stars, for the observed statistical properties of stars and clusters.
Spiral galaxy NGC 1232
Spiral galaxies display billions of stars caught up in the gravitational swirl of spiral arms revolving about the center. Young star clusters and nebulae, the nurseries where new stars are forming, are located along the spiral arms, together with dense molecular gas out of which the stars form. All galaxies dwell in cores of vast, massive “dark matter” halos, which are responsible for driving the dynamic, and ever-changing spiral patterns.
The equation derived by U-M Professor Sally Oey describes represents a model for the gradual pollution in galaxies by stellar by-products. Like other natural sciences, astronomy is highly quantitative, generating numerical models and predictions that must agree with observations.
Chandra X-ray Observatory
NASA’s orbiting Chandra X-ray Observatory is the most sensitive X-ray telescope ever built. It is used to study energetic phenomena like hot young stars and supernova explosions from dying stars. Several U-M astronomers use Chandra to study 10 million-degree gas from galaxy clusters and particles just seconds away from falling into distant black holes. At 45 feet long, Chandra is the largest satellite ever launched, and with its resolving power, you could read a traffic sign 12 miles away. Yet, the entire Chandra spacecraft operates on only 2 kilowatts, about the same power as a hair dryer.
Supernova remnant Cassiopeia A
A supernova remnant is the hot cloud from a tremendous explosion that usually marks the death of a massive star. The Cassiopeia A supernova remnant emits strongly in X-rays, as observed by the Chandra X-ray Observatory. The point source in the center is probably a rapidly spinning neutron star, which is all that remains of the parent massive star. Neutron stars are about 1.5 times the mass of the Sun but are only about 7 miles across. They are composed of the densest form of matter, so dense that one teaspoon weighs over 5 billion tons.
Rotating galaxy NGC 253
A spiral galaxy is a rapidly rotating, flat disk of stars and gas which looks elliptical because of its orientation. Light from the side moving toward us is blue-shifted, while light from the side moving away from us is red-shifted, as depicted in this representation of the galaxy NGC 253. The radio emission here is from atomic hydrogen, revealing most of the galaxy’s gas content. NGC 253 is starburst galaxy, forming stars at an extraordinarily high rate. This radio observation of NGC 253 is from the Australia Telescope Compact Array by Dr. Baerbel Koribalski.
The Green Bank Telescope
Radio waves are the least energetic form of electromagnetic radiation, and are emitted by a variety of sources ranging from cold atomic and molecular gas to relativistic electrons gyrating in magnetic fields. The Robert C. Byrd Green Bank Telescope (GBT) is the world’s largest, fully steerable radio telescope, with a diameter of about 100 meters. It is designed to detect radio waves with wavelengths from 9 feet long down to 1/8 inch. The GBT is located in Green Bank, West Virginia, and stands 485 feet high. The telescope weighs 16 million pounds and points with an accuracy of one arcsecond, the width of a single human hair seen six feet away. Its paneled metal surface covers almost two acres.
Simulation of relativistic jet
Active galactic nuclei and quasars, the most luminous objects in the Universe, host supermassive black holes which devour vast amounts of matter. Gas is funneled into enormous jets shooting away from the black hole at nearly the speed of light. U-M astronomer Dr. Philip Hughes uses computer simulation to model a jet driving a bow shock, like a ship plowing through water. The hydrodynamic modeling technique is similar to that used to study the flow of air over an airplane’s wing, but includes Einstein’s Theory of Special Relativity, because of the jet’s speed. Such studies probe the black hole environment that drives the jet, and the impact of active galaxies on their surroundings.
This project has been supported with funding from the Department of Astronomy and the Winter 2009 LSA Theme Semester, The Universe: Yours to Discover
