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 29
th
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
|