ASTR 101(F)Stars: From Suns to Black Holes

For the new era of "multimessenger astronomy": What makes a star shine? For how long will the Sun keep shining and what will happen to it then? What are black holes and how can they form? How and what have we found out about the recently discovered "chirps" from gravitational radiation resulting from two giant black holes merging and, with additional signals in the spectrum, from the merger of two neutron stars? What do we learn about the Sun from total solar eclipses? Astronomy 101, a non-major, general introduction to the part of contemporary astronomy that includes how stars form and how they end their existence, will provide answers to these questions and more. The course gives special attention to the exciting discoveries of the past few years. Topics include modern astronomical instruments such as the Hubble Space Telescope, the Chandra X-ray Observatory, the Kepler, K2 and TESS missions to discover planets around other stars, the latest huge telescopes and some results from them; how astronomers interpret the light received from distant celestial objects; the Sun as a typical star (and how its future will affect ours); and our modern understanding of how stars work and how they change with time. We will also discuss how pulsars and black holes result from the evolution of normal, massive stars and how supermassive black holes lurk at the center of galaxies and quasars. We will discuss the discovery of thousands of "exoplanets" around stars other than the Sun. We regularly discuss the latest news briefs and developments in astronomy and relate them to the topics covered in the course. This course is independent of and on the same level as Astronomy 102 (solar system) and 104 (galaxies and cosmology), and students who have taken those courses are welcome. Observing sessions will include use of the 24-inch telescope and other telescopes for nighttime observations of stars, star clusters, planets and their moons, nebulae, and galaxies, as well as use of other telescopes for daytime observations of the Sun. [ more ]

ASTR 102(S)Our Solar System and Others

What makes Earth different from all the other planets? What has NASA's Curiosity on Mars found about Mars's past running water and suitability for life? How has knowledge about Pluto been transformed by NASA's 2015 flyby and the associated ground-based studies with which Williams College faculty and students participate? Will asteroids or comets collide with the Earth again? What is a solar eclipse like? What do we learn from the rare transits of Mercury and of Venus that Williams faculty and students have studied? Astronomy 102, a non-major, general introduction to the part of contemporary astronomy that comprises the study of the solar system, will provide answers to these questions and more. We will cover the historical development of humanity's understanding of the solar system, examining contributions by Aristotle, Ptolemy, Copernicus, Galileo, Newton, Einstein, and others. We will discuss the discovery of over 4000 exoplanets around stars other than the Sun. The course gives special attention to exciting discoveries of the past few years by space probes and by the Hubble Space Telescope and the Kepler/K2/TESS missions. We regularly discuss the latest news briefs and developments in astronomy and relate them to the topics covered in the course. This course is independent of, and on the same level as Astronomy 101 (stars and stellar evolution) and 104 (galaxies and cosmology), and students who have taken those courses are welcome. [ more ]

ASTR 104The Milky Way Galaxy and the Universe Beyond

Last offered Spring 2019

It has been less than a century since the Sun was discovered not to be at the center of the Milky Way Galaxy, and the Milky Way Galaxy was determined to be only one of countless "island universes" in space. A host of technological advances is enabling us to understand even more clearly our place in the universe and how the universe began. For example, the recently discovered "chirp" from gravitational radiation (reported in 2016) resulting from two giant black holes merging, and the "chirp" from two neutron stars merging, also producing light, radio and x-ray radiation, has opened a whole different way of observing the Universe from the traditional use of light and other forms of electromagnetic radiation. We are now therefore in the new era of multimessenger of astronomy.Further, the Hubble Space Telescope and the Chandra X-ray Observatory bring exceptionally clear images over a wider range of the spectrum; their images are aiding astronomers to better understand the past and future of the Universe, and new infrared images are expected with the launch of the James Webb Space Telescope. Observations with those and other new telescopes on the ground and in space help to confirm and enlarge our understanding of the Big Bang. In addition, study of the early Universe (most recently from the Planck spacecraft) and large-scale mapping programs such as the Sloan Digital Sky Survey and the Dark Energy Survey are giving clues into how the Universe's currently observed structure arose. Astronomy 104, a non-major, general introduction to part of contemporary astronomy comprising the study of galaxies and the Universe, explores the answers to questions like: What is the Milky Way?; Why are quasars so luminous?; Is the Universe made largely of "dark matter" and "dark energy"?; What determines the ultimate fate of the Universe? How have studies of Cepheid variables and distant supernovae with the Hubble Space Telescope determine that the Universe is 13.8 billion years old and indicated that the Universe's expansion is accelerating? How significant is the current discrepancy between the age and expansion rate of the Universe as measured from supernova observations as opposed to measurements from the cosmic background radiation? We regularly discuss the latest news briefs and developments in astronomy and relate them to the topics covered in the course. This course is independent of, and on the same level as Astronomy 101 and 102, and students who have taken those courses are welcome. [ more ]

ASTR 111(F)Introduction to Astrophysics

The science of astronomy spans vast scales of space and time, from individual atoms to entire galaxies and from the universe's beginning to the future fate of our Sun. In this course, we will survey some of the main ideas in modern astrophysics, with an emphasis on the physics of stars and galaxies. ASTR 111 is the first course in the Astrophysics and Astronomy major sequences. It is also appropriate for students planning to major in one of the other sciences or mathematics and for others who would like a quantitative introduction that emphasizes the relationship of contemporary physics to astronomy. Topics include gravity and orbits, radiation laws and stellar spectra, physical characteristics of the Sun and other stars, star formation and evolution, black holes, galaxies, the expanding universe, and the Big Bang. Students will also use telescopes to observe stars, nebulae, planets, and galaxies and to make daytime observations of the Sun. [ more ]

ASTR 207 TExtraterrestrial Life in the Galaxy: A Sure Thing, or a Snowball's Chance?

Last offered Fall 2016

A focused investigation of the possibility of life arising elsewhere in our Galaxy, and the chances of our detecting it. In this course, pairs of students will explore the astronomical and biochemical requirements for the development of Earth-like life. We will consider the conditions on other planets within our solar system as well as on newly-discovered planets circling other stars. We will also analyze the famous "Drake Equation," which calculates the expected number of extraterrestrial civilizations, and attempt to evaluate its components. Finally, we will examine current efforts to detect signals from intelligent alien civilizations and contemplate humanity's reactions to a positive detection. [ more ]

ASTR 211(S)Astronomical Observing and Data Analysis

How do astronomers make scientific measurements for objects that are light-years away from Earth? This course will introduce the basics of telescopes and observations and will give students hands-on training in the techniques astronomers use to obtain, process, and analyze scientific data. We will discuss observation planning, CCD detectors, signal statistics, image processing, and photometric and spectroscopic observations. We will begin by focusing on ground-based optical observations and will move on to non-optical observations, both electromagnetic (e.g., radio waves, X-rays) and non-electromagnetic (e.g., gravitational waves, neutrinos). Throughout the course, students will use computational techniques to work with real astronomical data, taken with our 24" telescope and from data archives. [ more ]

ASTR 217(S)Planets and Moons

This course will examine the history and geology of the solar system. No two planets are exactly alike, and as we acquire more data and higher-resolution images, our sense of wonder grows. However, we can't hike around and hammer rocks on Venus or Titan, so we have to infer composition, form, texture and process from remotely-captured images and sparse chemical and spectral data. We will consider the origin of the solar system, the formation and evolution of planetary bodies, and the role of impacts, volcanism, tectonics and geomorphology in shaping them. We will summarize basic geological concepts of stratigraphy, structure and chronology and show how they can be applied off-world. We will review solar system exploration, and will include planetary data in lab exercises. [ more ]

ASTR 240Great Astronomers and Their Original Publications

Last offered Fall 2018

We study many of the greatest names in the history of astronomy, consider their biographies, assess their leadership roles in advancing science, and examine and handle the first editions of their books and other publications. Our study includes, in addition to a Shakespeare First Folio (with its astronomical mentions) and a page from the Gutenberg Bible, original books such as: 16th-century, Nicolaus Copernicus (heliocentric universe); Tycho Brahe (best pre-telescopic observations); 17th-century, Galileo (discoveries with his first astronomical telescope, 1610; sunspots, 1613; Dialogo, 1632); Johannes Kepler (laws of planetary motion, 1609, 1619); Johannes Hevelius and Elisabeth Hevelius (atlases of the Moon and of stars, 1647, and 1687); Isaac Newton (laws of universal gravitation and of motion, 1687); 18th-century, Edmond Halley (Miscellanea curiosa, eclipse maps, 1715, 1724); John Flamsteed and Margaret Flamsteed (Atlas Coelestis, 1729); William Herschel and Caroline Herschel (1781, 1798). In more recent centuries, the original works are articles: 20th--century: Albert Einstein (special relativity, 1905; general relativity, 1916); Marie Curie (radioactivity); Cecilia Payne-Gaposchkin (hydrogen dominating stars, 1929), Edwin Hubble (Hubble's law, 1929); Vera Rubin (dark matter, 1970s); Jocelyn Bell Burnell (pulsar discovery, 1968); 21st-century: Wendy Freedman (Universe's expansion rate, 2000s). We will also read biographies and recent novels dealing with some of the above astronomers. With the collaboration of the Chapin Librarian, we will meet regularly in the Chapin Library of Rare Books and also have a session at the library of the Clark Art Institute to see its rare books of astronomical interest. The course is a repeat of the successful course first given during the 2014-15 academic year's Year of the Book, honoring the new Sawyer L ibrary and the expansion of the Chapin Library of Rare Books. [ more ]

ASTR 330The Nature of the Universe

Last offered Spring 2019

This course is a journey through space and time from the first fractions of a second after the Big Bang to the ultimate fate of the Universe billions of years into the future. Topics include the Big Bang and its remnant cosmic background radiation, cosmic inflation, conditions during the first three minutes, creation of the elements, stellar and galactic black holes, relativity, the detection of gravitational waves from the merging of two massive stellar black holes more than a billion light-years away, galaxies and quasars, and formation of the large-scale structure of the Universe. We will explore current ideas about the fate of our Universe, including the acceleration of its expansion, and its implications for the end of time. Finally, we will consider the fantastic but serious theoretical proposal that ours is but one of countless universes existing within a multiverse. [ more ]

ASTR 336Science, Pseudoscience, and the Two Cultures

Last offered Spring 2018

A famous dichotomy between the sciences and the humanities, and public understanding of them, was laid down by C. P. Snow and has been widely discussed, with ignorance of the second law of thermodynamics compared with ignorance of Shakespeare. In this seminar, we will consider several aspects of science and scientific culture, including how scientific thinking challenges the claims of pseudoscience. We will consider C. P. Snow and his critics as well as the ideas about the Copernican Revolution and other paradigms invented by Thomas Kuhn. We will discuss the recent "Science Wars" over the validity of scientific ideas. We will consider the fundamental originators of modern science, including Tycho, Kepler, Galileo, and Newton, viewing their original works in the Chapin Library of rare books and comparing their interests in science with what we now call pseudoscience, like alchemy. We will review the history and psychology of astrology and other pseudosciences. Building on the work of Martin Gardner in Fads and Fallacies in the Name of Science, and using such recent journals as The Skeptical Inquirer and The Scientific Review of Alternative Medicine, we consider from a scientific point of view what is now called complementary or alternative medicine, including both older versions such as chiropractic and newer nonscientific practices. We will discuss the current global-climate-change deniers and their effects on policy. We discuss vaccination policy. We consider such topics as GM (genetically modified) foods, the safety and regulation of dietary supplements, and the validity of government and other recommendations relevant to the roles of dietary salt, sugar, and fat in health. We consider the search for extraterrestrial intelligence (SETI) and reports of UFO's and aliens. We consider the possible effects that superstitious beliefs have on the general public's cooperation in vaccination programs and other consequences of superstition. We will discuss conspiracy theories such as those about the Kennedy assassination, in view of the 2017 release of many documents from the time and the recent book by Alexandra Zapruder, the granddaughter of the person whose on-the-spot movie documented the fatal shot. We also consider a range of dramas that are based on scientific themes, such as Tom Stoppard's Arcadia and Michael Frayn's Copenhagen. [ more ]

ASTR 402 TBetween the Stars: The Interstellar Medium

Last offered Spring 2018

The matter between the stars--the interstellar medium--manifests itself in many interesting and unexpected ways, and, as the detritus of stars, its properties and behavior hold clues to the history and future evolution of both stars and the galaxies that contain them. Stars are accompanied by diffuse matter all through their lifetimes, from their birthplaces in dense molecular clouds, to the stellar winds they eject with varying ferocity as they evolve, to their final fates as they shed their outer layers, whether as planetary nebulae or dazzling supernovae. As these processes go on, they enrich the interstellar medium with the products of the stars' nuclear fusion. The existence of life on Earth is eloquent evidence of this chemical enrichment. In this course we will study the interstellar medium in its various forms. We will learn about many of the physical mechanisms that produce the radiation we observe from diffuse matter, including radiative ionization and recombination, collisional excitation of "forbidden" lines, collisional ionization, and synchrotron radiation. Applying our understanding of these processes, we will analyze the physical conditions and chemical compositions of a variety of nebulae. This course is observing-intensive. Throughout the semester students will work in small groups to design, carry out, analyze, and critique their own observations of the interstellar medium using the equipment on our observing deck. [ more ]

ASTR 404 T(S)Unsolved Problems in Galaxy Evolution

In this tutorial, we will learn about galaxies and their evolution by focusing on some of the key mysteries astronomers are trying to solve. Questions may include: How do galaxies turn their gas supply into stars? Is there a universal initial mass function for star formation? What is the origin of multiple stellar populations in globular clusters? Why do some galaxies cease star formation? Which galaxies reionized the universe? We will discuss the nature of each unsolved problem, debate the theories proposed to answer it, and consider how future progress might be made. [ more ]

ASTR 410Compact Stellar Remnants: White Dwarfs, Neutron Stars and Black Holes

Last offered Spring 2019

A star is a very interesting, very complicated physical object. Properties of stars and their evolutionary paths depend on an intricate interplay of different physical phenomena with gravity, nuclear interactions, radiation processes and even quantum and relativistic effects playing important roles. Using basic physics we will construct simple models of stars and discuss their evolution, concentrating on the key physical processes that play the dominant role at different evolutionary stages. We will discuss late stages of stellar evolution and concentrate on the basic properties of three possible remnants: white dwarfs, neutron stars and black holes. Radio and X-ray pulsars, supernovae including Type Ia and Gamma Ray Bursts will be discussed as well as observational confirmation of existence of black holes. We will explore extreme conditions existing near neutron stars and black holes and discuss their astrophysical consequences. We will also discuss the recent exciting detection of gravitational waves by the LIGO/VIRGO laser interferometric detectors. [ more ]

ASTR 412 T(F)Heliophysics

We study all aspects of the Sun, our nearest star. This semester follows the total solar eclipses of August 21, 2017, whose totality crossed the U.S. from coast to coast, and the July 2, 2019, total solar eclipse that crossed Chile and Argentina. In addition to discussing our observations of these eclipses and what has been learned about the solar atmosphere from eclipse research, we discuss the solar interior (including the Nobel-prize-winning solar neutrino experiment and helioseismology), the photosphere, the chromosphere, the corona, and the solar wind. We discuss the Sun as an example of stars in general. We discuss both theoretical aspects and observational techniques, including work at recent total solar eclipses. We discuss results from current spacecraft, including the Solar and Heliospheric Observatory (SOHO), the Solar Dynamics Observatory, the Sun Watcher (SWAP), and Hinode (Sunrise), and the new GOES/UVSI (Solar Ultraviolet Imager) run by an alumnus as well as additional Total Solar Irradiance measurements from ACRIMSAT and SORCE. We will discuss the role of solar observations in confirming Einstein's General Theory of Relativity with the bending of light at the 1919, 1922, and 2017 total solar eclipses as well as gravitational redshift measurements in solar spectral lines, extending our discussion to the recent "chirp" of gravitational radiation reported from several colliding black holes and neutron stars observed with the Laser Interferometer Gravitational-wave Observatory (LIGO). We hope to observe the transit of Mercury across the face of the Sun on November 11, 2019, during the semester; we also discuss our data analysis of recent transits of Mercury we observed from the ground and from space (most recently in May 2016). We will highlight the 2004 and 2012 transits of Venus across the face of the Sun as observed from Earth, the first such transits of Venus since 1882, as well as our work in observing transits of Venus from Jupiter with the Hubble. [ more ]

ASTR 493(F)Senior Research: Astronomy

An original experimental or theoretical investigation is carried out under the direction of a faculty member in Astronomy, as discussed under the heading of the degree with honors in Astronomy above. This is part of a full-year thesis (493-494). [ more ]

ASTR 494(S)Senior Research: Astronomy

An original experimental or theoretical investigation is carried out under the direction of a faculty member in Astronomy, as discussed under the heading of the degree with honors in Astronomy above. This is part of a full-year thesis (493-494). [ more ]

ASTR 495(F)Senior Research: Astrophysics

An original experimental or theoretical investigation is carried out under the direction of a faculty member in Astronomy or Physics, as discussed under the heading of the degree with honors in Astrophysics above. [ more ]

ASTR 496(S)Senior Research: Astrophysics

An original experimental or theoretical investigation is carried out under the direction of a faculty member in Astronomy or Physics, as discussed under the heading of the degree with honors in Astrophysics above. [ more ]

ASTR 499(F, S)Physics and Astronomy Colloquium

Physicists and Astronomers from around the country come to explain their research. Students of Physics and Astronomy at any level are welcome. Registration is not necessary to attend. A non-credit course. [ more ]