ASTRONOMY DEPARTMENT AND THE HOPKINS OBSERVATORY

Faculty included Jay M. Pasachoff, Field Memorial Professor of Astronomy, Chair of the Astronomy Department and Director of the Hopkins Observatory; Karen B. Kwitter, Ebenezer Fitch Professor of Astronomy; and Stephan E. Martin, Instructor in Astronomy and Observatory Supervisor.

The department enrolled the most astrophysics and astronomy majors ever: 9 juniors in the class of ’02 and 8 seniors in the class of ’01. Four astrophysics seniors in the class of ’00 graduated. Incoming astrophysics seniors are Misa Cowee ’01, Kenneth Dennison ’01, Joel Iams ’01, Duane Lee ’01, Daniel Seaton ’01, Joey Shapiro ’01, Matthew Silver ’01, and Darik Vélez ’01. Incoming astrophysics juniors are Daniel Bissex ’02, Gabriel Brammer ’02, Shoshana Clark ’02, Bethany Cobb ’02, Rossen Djagalov ’02, Caleb Fassett ’02, David (Mike) Gioiello ’02 and David Glick ’02. William Allen ’02 will major in astronomy.

A major activity was the eclipse expedition to Romania for the 11 August 1999 total solar eclipse and the subsequent data reduction. Professor Pasachoff is primarily interested in studies related to the source of heating the solar corona to temperatures of millions of degrees. The expedition and data reduction are in collaboration with Dr. Bryce A. Babcock, Staff Physicist and Coordinator of Science Facilities. Stephan Martin, Observatory Supervisor, led one of the experiments. Jonathan Kern, an optics designer at Caltech’s Laser Interferometer Gravitational-Wave Observatory, was another senior member of the team, and helped with the design and fabrication of some of the equipment.

This was Pasachoff’s 29th solar eclipse. He is Chair of the Working Group on Solar Eclipses of the International Astronomical Union, for which his duties involve international coordination of information about eclipse expeditions and on eclipse observations.


Misa Cowee ’01, Kevin Russell ’00, Mark Kirby, Dr. Bryce Babcock
and Tim McConnochie ’98 on site at August 1999 eclipse in Romania.

The team in Romania included Williams College students Kevin Russell ’00, Sara Kate May ’00, Rebecca Cover ’00, Daniel Seaton ’01, Joey Shapiro ’01, Misa Cowee ’01, Darik Velez ’02, and Rossen Djagalov ’02; Keck Northeast Astronomy Consortium Summer Fellow Alexandru Ene ’02, a student from Romania who studied at Middlebury College and who has transferred to Harvard College; and Mark Kirby, from Deep Springs College in Dyer, Nevada, who is transferring to Harvard College. Recent Williams alumni Timothy McConnochie ’98 of JPL, who began graduate school in planetary science at Cornell in September 2000, and Christina Reynolds ’97, then of the University of North Carolina and now of the Adler Planetarium in Chicago, were also on site. Lee Hawkins, formerly the Keck Northeast Astronomy Consortium technician and now at Appalachian State University, supervised one of the experiments. Dr. Allan Ridgeley, of the Rutherford Appleton Laboratory, England; Professor Marek Demianski, of the Copernicus Astronomical Center in Warsaw, who will be a Visiting Professor of Astronomy at Williams from January 2001 through June 2002; Mitzi Adams of the NASA Marshall, Space Flight Center; and Paul Rosenthal joined the group in Romania. Several of Pasachoff’s eclipse photos appeared in the Geographica section of National Geographic Magazine for February 2000.

The expedition was supported by grants Pasachoff received from the Atmospheric Sciences Division of the National Science Foundation, from NASA’s Guest Investigator Program for the Solar and Heliospheric Observatory spacecraft, and from the Committee for Research and Exploration of the National Geographic Society. Additional support was received from the Massachusetts Space Grant (through M.I.T. from NASA) and the W.M. Keck Foundation through the Keck Northeast Astronomy Consortium. Further support at Williams came from the Mellon Minority Grant, the Safford Fund (set up by his descendents in honor of the second director of the Hopkins Observatory, Truman Henry Safford), and the Bronfman Science Center.

The team observed from Rimnicu Vilcea, Romania, about two hours’ drive northwest of Bucharest. Pasachoff also advised Dr. Magdalena Stavinschi, Director of the Astronomical Institute of the Romanian Academy of Sciences in Bucharest, and her staff on the use of some of their large telescopes during the eclipse to make high-resolution observations of the solar corona. Supported by a NATO grant involving Dr. Stavinschi, Professor Pasachoff, and Dr. Allan Ridgeley of Rutherford Appleton Laboratory in England, the three coordinated observations and exchanged visits. Dr. Stavinschi visited Williamstown in April 2000.

Two of the experiments deal with the still open question of how the corona, the outermost layer of the sun’s atmosphere, can reach a temperature of 2 million degrees Celsius (about 4 million degrees Fahrenheit), even though the everyday surface of the sun below it is only 6,000 degrees Celsius (about 11,000 degrees Fahrenheit). The third experiment is in liaison with scientists in charge of an experiment on the Solar and Heliospheric Observatory (SOHO) spacecraft. The observations are possible only during the brief minutes of a total solar eclipse, when the everyday sun is hidden by the moon, allowing the faint corona to be observable from earth. On ordinary days, the corona is hidden by the blue sky, since it is about a million times fainter than the layer of the sun we see shining every day, the photosphere. Pasachoff, together with Dr. Leon Golub of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, is co-author of the first textbook about the solar corona to be written in decades; it was published in 1997. Golub and Pasachoff have a general book in press on the Sun at Harvard University Press for publication in 2001. A draft copy of this book was used in a junior/senior tutorial during the spring of 2000.

The first eclipse experiment is a search for rapid oscillations in the corona, with periods of about 1 second. Pasachoff and his colleagues and students have developed techniques over the last two decades to observe in the so-called “coronal green line,” a color in which the corona emits light especially strongly, with time resolution so fast that such short periods can be detected. Oscillations with periods in that short range are predicted by some theories that hold that the extreme coronal heating is caused by vibrations of magnetic loops. The loops of gas, held in place by the sun’s magnetic field, have been observed, and the question is whether their vibrations bring enough energy into the corona to heat it sufficiently. Kevin Russell ’00 participated with Babcock and McConnochie to operating the equipment on site. He then devoted his senior thesis to the reduction of the data. A paper on which he is co-author with Pasachoff, Babcock, and McConnochie about the earlier eclipse data from 1994 and 1998 eclipses is in press in the journal Solar Physics. His thesis involved calibrating and aligning data, calculating Fourier transforms using the Interactive Data Language (IDL), and comparing with modeled data that he constructed. The results indicate the presence of excess oscillatory power at the locations of coronal loops, endorsing the model of coronal heating. The experiment in Rimnicu Vilcea was supported by the grant from the Atmospheric Sciences Division of the National Science Foundation for the 1999 eclipse, and a similar grant has been awarded for the 2001 eclipse.

The second experiment is a map of the polarization and temperature of the corona, using a technique of comparing electronic images of the corona taken at special ultraviolet wavelengths. Following theoretical work, these wavelengths are chosen to include two such at which the difference between the shape of the everyday sun’s spectrum and the corona’s spectrum is especially striking. The experiment was supported at the 1998 and 1999 eclipses by grants from the Committee for Research and Exploration of the National Geographic Society. Lee Hawkins and Sara Kate May ’00 operated the equipment on site, along with Misa Cowee ’01 and Alex Ene ’02. (Cowee and Ene also tested and operated on site an Ocean Optics spectrometer used to monitor the wavelength of the narrow-band filter in the oscillation experiment.) May devoted her senior thesis to the analysis of the data. She produced maps of the coronal polarization for the quadrant of the Sun observed, and maps of relative temperature showing the temperature rise from the solar limb up through the lower corona, though the statistical accuracy was insufficient to detect temperature variations from coronal streamers to the non-streamer background. Calibration steps continue to be carried out in order to provide absolute temperature. Various tests and modifications of the equipment are being made in order to improve the data at the 2001 eclipse. Pasachoff, Babcock, Russell, and May summarized their results at the American Astronomical Society meeting in Rochester, NY, in June 2000.

The third experiment is to image the solar corona during the eclipse to compare with observations of the corona seen with the Extreme-ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO), in collaboration with scientists at NASA’s Goddard Space Flight Center. The features seen at the eclipse outside the solar disk can be matched up with their bases on the solar disk with the EIT experiment. Further, the experiment uses a lens that gives an image at the same scale and with a green filter that matches a filter in one of the telescopes in the coronagraph system on SOHO that operated for the 1998 eclipse but is no longer working. This observation was originally in collaboration with the late Dr. Guenter Brueckner of the Naval Research Laboratory in Washington, D.C., principal investigator of that experiment, LASCO (Large Angle Spectrographic Coronagraph), and is now in collaboration with Dr. Russell Howard and with other scientists at NRL. Daniel Seaton ’01 picked up the data reduction during the summer of 2000. The comparison of the 1998 eclipse image with an image taken with one of LASCO’s coronagraphs will provide a calibration of how much light was scattered in that coronagraph (C1) in the process of making an artificial eclipse on board the spacecraft. Such artificial eclipses cannot quite match the quality of a natural eclipse, in which the moon hides the sun’s light before it reaches a telescope. The data from the 1999 eclipse, made in a wavelength that passed only radiation from 1-million-degree coronal gas (the “coronal green line”) will be interposed between EIT observations of low solar levels and LASCO observations of the outer solar corona. (See images and descriptions at http://www.williams.edu/astronomy/eclipse.) Stephan Martin is the collaborating Williams College staff member. The experiment at the 1999 eclipse was funded by a grant from NASA’s Guest Investigator Program for the SOHO spacecraft.

Joey Shapiro ’01 and Darik Vélez ’02, in addition to general expeditionary work, participated with Dr. Paul Rosenthal in making two digital videos of the eclipse.

Rossen Djagalov ’02 and Christina Reynolds ’97 observed the eclipse from the Bucharest Observatory, where they had equipment in readiness. The weather was not as favorable for observing at that site, though, as it was at the main Williams site in Rimnicu Vilcea.

In his eclipse work, Pasachoff was busy not only on scientific tasks, but also on educational tasks relevant to the safe observing of the eclipse by populations across Europe, Through his roles as Chair of the Working Group on Solar Eclipses of the International Astronomical Union (IAU) and as Chair of the Subcommittee on Public Education through Eclipses of the Commission on the Teaching of Astronomy of the IAU. (See http://www.williams.edu/astronomy/IAU_eclipses/ .)
Another set of observations in which Pasachoff has been involved is the study of interstellar deuterium. Deuterium is particularly important to study for cosmology, since all the deuterium in the Universe was formed in the first thousand seconds after the Big Bang, and all subsequent processes destroy deuterium. Pasachoff has been working for some years with Dr. Donald A. Lubowich of the American Institute of Physics and Hofstra University on studies of deuterium from various points of view. Their studies of deuterium in the deuterated molecule DCN in the Sagittarius A molecular cloud only 30 light years from the center of our Milky Way Galaxy was published in the journal Nature for 29 June 2000. They found about one part in 106 is deuterium compared with hydrogen, a factor of about 1,000,000 more than had been predicted for the galactic center, where the close proximity of many stars should have destroyed essentially all the deuterium. The value they find is a factor of about 10 lower than the deuterium value found in our galaxy close to the Sun, and is the farthest known deuterium abundance in our galaxy. During the past year, they brought in Dr. Tom Millar and Helen Roberts of the University of Manchester Institute of Science and Technology to provide molecules of the chemical fractionation that makes the D/H ratio separate from the DCN/HCN ratio. The results were published jointly, including also Williams alumnus Robert P. Galloway ’96, who had worked on the data when he was an undergraduate, and Colgate alumna Christy Tremonti ’97.

Rebecca Cover ’00 worked at the Harvard-Smithsonian Center for Astrophysics (CfA) on an investigation of the double star cluster known as h and Ç Persei. The project originated in a joint investigation between Pasachoff and Nancy Evans and Scott Wolk of the CfA to link optical observations of the clusters to x-ray images obtained with the Roentgen Satellite (ROSAT). Cover, beginning during the summer of 1999 and continuing during the academic year for her senior thesis, processed and studied a series of CCD (electronic camera) optical images taken by Wolk at the Kitt Peak National Observatory. She worked with about 70,000 stars, each of which appeared in images taken through five different color filters. By creating color-magnitude diagrams and comparing them with theoretical models, she separated cluster members from foreground and background objects. Her results bear on age, distance, reddening, and other parameters of the clusters, two of the most prominent in the northern-hemisphere sky.

Caleb Fassett ’02, beginning with summer work in 1999 at the Carnegie Institution of Washington’s Department of Terrestrial Magnetism, has been part of a team using data from the Hubble Space Telescope’s Key Project on the cosmic distance scale to investigate the age of the Universe. He is included as a co-author of a major paper in the Astrophysical Journal on the use of Cepheid variable stars to calibrate the distance to Type Ia supernovae, which arise from the incineration of white-dwarf stars. (Since all these supernovae have the same mass when they explode, they reach the same peak brightness, and thus are good “standard candles” for seeing exceedingly far out into the Universe and thus far back in time.) More recently, along with his advisor, John A. Graham of DTM, he was co-author of a forthcoming Astrophysical Journal paper on young, bright blue stars in galaxy NGC 5128 (Centaurus A). Fassett and Graham obtained photometry for two fields using CCD images from the 2.5-m du Pont telescope at Las Campanas Observatory in Chile. The blue stars are closely associated with the galaxy’s radio jet and were likely created by shocked star formation. A second field closer to Centaurus A’s nucleus was also examined, and was the subject of a poster Graham delivered at the Rochester meeting of the American Astronomical Society in June 2000.

Pasachoff completed the revision of his Field Guide to the Stars and Planets, and the fourth edition was published, with tables and graphs valid through the year 2010. He continued work on “Astronomical Tables,” a chapter in Physicists’ Desk Reference (Springer-Verlag), and was co-author of the entry on the Sun for the World Book Encyclopedia.
Pasachoff continues on the science board of the World Book and as consulting editor for astronomy of the McGraw-Hill Scientific Encyclopedia and Yearbooks. He continues on the advisory board of Odyssey, an astronomy magazine for children. He became a consultant to Microsoft’s Encarta, a CD-ROM encyclopedia.

Student roof TA’s are responsible for operating the telescopes, participating in research projects, and assisting introductory students with assignments. The TA’s included Bethany Cobb ’02, Misa Cowee ’01, Rossen Djagalov ’02, Kathleen Gibbons ’03, Max Niederste-Ostholt ’02, Daniel Seaton ’01, Joey Shapiro ’01, Jason Slingerlend ’00, Christopher Spence ’00, and Gabriel Brammer ’02.

The Milham Planetarium was run by Kevin Russell ’00, Sara Kate May ’00, and Darik Vélez ’01. The fall show was “The 1999 Williams College Eclipse Expedition to Romania.” Summer shows were given by the summer research students.

During the summer of 2000, the following Keck exchange students were in residence at Williams: Sun-Mi Chung (Wesleyan ’02), working with Karen Kwitter, and Jason Ostenson (Vassar ’02) working with Jay Pasachoff. Williams students working on research in the summer of 2000 were Gabe Brammer ’02 (working with Karen Kwitter) and Daniel Seaton ’01 and Mike Gioiello ’02 (working with Jay Pasachoff.) Joey Shapiro ’01 started her thesis on the topology of the Universe under Professor Marek Demianski, who will be visiting in the spring of 2001, and Professor Colin Adams of the Math Department.

Williams astronomy and astrophysics students doing research off campus during the summer of 2000 were: Darik Velez ’02, at the Arecibo Observatory, Puerto Rico, supported by the National Astronomy and Ionospheric Observatory Summer Program; Bethany Cobb ’02 at Middlebury College; Rossen Djagalov ’02 at Wesleyan University; Kathleen Gibbons ’03 at Colgate University and Joel Iams ’01 at Vassar College. The latter four students were supported by the Keck Northeast Astronomy Consortium.

Kwitter and her colleagues continue their studies of planetary nebulae – glowing gas shells ejected by dying stars. (See http://oposite.stsci.edu/pubinfo/pr/97/pn/.) The chemical composition of these extraordinarily beautiful and complex objects yields important clues as to the nature of the nuclear processing that went on inside the parent star. These stars, which make up the majority of those in our Milky Way Galaxy, have masses between about 0.8 and 10 times the mass of our Sun. In addition to the evolutionary history of their progenitors, planetary nebulae as a class offer an opportunity to study the properties of the surrounding interstellar medium and the chemical evolution of the Galaxy as a whole.

Kwitter and Dick Henry, University of Oklahoma, have finished a new determination of carbon abundances in planetary nebulae. They used newly recalibrated archived data from the International Ultraviolet Explorer satellite to study the production of carbon in stars that produce planetary nebulae. Jim Bates ’98, Leila Zelnick ’00, Joel Iams ’01, and Keck summer exchange students Kelli Corrado ‘99, Colgate University, and Hugh Crowl ’00, Wesleyan, contributed to this project by obtaining and/or analyzing spectra from planetary nebulae.

Kwitter, Henry and Bruce Balick, from the University of Washington, are in the midst of a multi-faceted project to study planetary nebulae as individual objects and as probes of chemical evolution in the Galaxy, and possible in other galaxies as well. Students are participating in the work during summers and academic years. Their work is funded by an NSF grant.

Kwitter continued to serve on the Space Sciences panel of the National Research Council Associateship Programs Review. The NRC is the principle operating agency of the National Academy of Sciences and National Academy of Engineering, and awards postdoctoral and senior associateships at national facilities. She also served on the Hubble Space Telescope Cycle 9 Review Panel and on the NSF Stars and Stellar System proposal review panel. In addition, she was appointed to a three-year term on the selection committee for the Annie Cannon Award given by the American Astronomical Society, and a three-year term on the AAS’s Committee on the Status of Women in Astronomy.

Kwitter attended the 2nd Conference on Asymmetrical Planetary Nebulae at MIT in August 1999, where she presented a paper on her work with Henry.

Under the guidance of Steve Martin, the observatory continues to be used in support of the astronomy curriculum. Over 86 introductory astronomy students completed at least five observations of celestial objects over the course of the academic year. These included observations, photographs, and CCD images of the sun, moon, planets, nebulae, galaxies, as well as Nova Aql 1999, No. 2, the first nova visible to the naked eye in over 25 years.

Martin participated in the Williams College Eclipse Expedition to Rimnicu Vilcea, Romania, in August. He supervised an experiment carried out during the total solar eclipse to image the solar corona during the eclipse at the same scale and with the same green filter as a filter in the coronagraph experiment on board the Solar and Heliospheric Observatory (SOHO). He is working during the summer of 2000 with Daniel Seaton ’01 in the analysis of these data, and preliminary images are viewable at http://www.williams.edu/astronomy/eclipse99/.

Martin continued his responsibilities for maintaining the World Wide Web pages for the Astronomy department and, sponsored by Saunders College Publishing, for Pasachoff On-Line, a site devoted to Pasachoff’s introductory astronomy textbook, Astronomy: From the Earth to the Universe. Martin also developed and maintains web pages for each of the introductory astronomy courses and the observatory. See http://www.williams.edu/astronomy. These pages contain links to useful astronomy sites and provide a forum for students to display images that they have taken with the observatory’s CCD system and photographic cameras as part of their observing projects. There are also pages dedicated to observations made by the Williams College eclipse teams at the total solar eclipses in Aruba and Romania (See http://www.williams.edu/astronomy/eclipse/.).


ASTRONOMY COLLOQUIA

Stephanie Wilson, Bernhard Visiting Fellow, NASA Astronaut
Lyndon B. Johnson Space Center, Houston, Texas
“Observing the Sky with a NASA Space Mission”
Class of 1960’s Scholars Program
Dr. Magda Stavinschi
Director, Astronomical Institute, Bucharest, Romania
“The Eclipse in Romania”
Class of 1960’s Scholars Program
Dr. Peter Foukal
CRI Inc., Boston, MA
“New Insights into Solar Luminosity Variation and Its Influence on Climate”

OFF-CAMPUS ASTRONOMY COLLOQUIA AND LECTURES

Professor Jay M. Pasachoff
“The Sun and Solar Eclipses”
L’hemisféric, Valencia, Spain
Professor Jay M. Pasachoff
“Solar Eclipse Expeditions”
Amateur Astronomers Association of New York
Professor Jay M. Pasachoff
“The Sun and Solar Eclipses”
American Museum of Natural History/Rose Center for Earth and Space, New York
Professor Jay M. Pasachoff, Bryce A. Babcock, Kevin Russell, Misa Cowee ‘01, Alex Ene, Mark Kirby, Sara Kate May ’00, Tim McConnochie ’98, Leon Golub, Ed Deluca, C. Jacob Wolfson, and Katherine Reeves
“Simultaneous Eclipse and TRACE Observations of Coronal Loops”
NASA TRACE Workshop, Monterey, CA
Professor Karen Kwitter
“The Lives of Stars”
Williamstown Elementary School Science Night

POSTGRADUATE PLANS OF ASTROPHYSICS & ASTRONOMY MAJORS

ASTROPHYSICS

Rebecca T. Cover

Peace Corps in Senegal

Sara Kate May

Teaching at Riverdale School, New York

Kevin D. Russell

Fulbright Fellowship to Australia

Jason B. Slingerlend

Financial services, Colorado

ASTRONOMY

Robert C. Foxwell

Graduate school in Anthropology