Professor of Astronomy, Emeritus
Contact
Education
Ph.D., University of California, Santa Cruz
B.A., Swarthmore College
About
I own a 32-inch telescope on Cape Cod and enjoy having students use it with me. I also enjoy snorkeling, radio control glider and helicopter flying, paragliding, tennis, movies and reading.
Publications
The Monitoring of Transient Lunar Phenomena
Doorn, Jarrel; Eaton, M.; Ahrendts, G.; Barker, T.
American Astronomical Society, AAS Meeting #218, #224.06; Bulletin of the American Astronomical Society, Vol. 43, 2011
Rotation Period Determination for 180 Garumna: A Triumph of Global Collaboration
Pilcher, Frederick; Benishek, Vladimir, Delos, Shelby; Barker, Timothy; Ahrendts, Gary; Hamanowa, Hiromi; Hamanowa, Hiroko; Higgins, David
The Minor Planet Bulletin (ISSN 1052-8091). Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers, Vol. 39, No. 2, p. 46 (2012)
Light Curve of Minor Planet 1026 Ingrid Delos, S.; Ahrendts, G.; Barker, T.
The Journal of the American Association of Variable Star Observers, vol. 40, no. 1, p. 423
Rotation Period Determination for 247 Eukrate Pilcher, Frederick; Delos, Shelby; Ahrendts, Gary; Barker, Timothy. The Minor Planet Bulletin (ISSN 1052-8091). Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers, Vol. 39, No. 4, p. 204 (2012)
Spectrophotometry of Planetary Nebulae I. Physical Conditions (Astrophysical Journal, 219, 914, 1978)
Spectrophotometry of Planetary Nebulae II. Chemical Abundance (Astrophysical Journal, 220, 193, 1978)
Spectrophotometry of Planetary Nebulae III. Sulfur Abundances (Astrophysical Journal, 221, 145, 1978)
A Comparison of Continuum and Forbidden-Line Electron Temperatures in Gaseous Nebulae (Astrophysical Journal, 227, 863, 1979)
Low Argon Abundances in Three Halo Planetary Nebulae (Astrophysical Journal, 237, 482, 1980)
The Ionization Structure of the Ring Nebula I. Sulfur and Argon (Astrophysical Journal, 240, 99, 1980)
The Ionization Structure of the Ring Nebula II. Ultraviolet Observations (Astrophysical Journal, 253, 167, 1982)
The Ionization Structure of Planetary Nebulae III. NGC 7009 (Astrophysical Journal, 267, 630, l983)
Low Sulfur Abundances in Three Halo Planetary Nebulae (Astrophysical Journal, 270, 641, 1983)
Chemical Abundances in a New Halo Planetary Nebula (with K. Cudworth) Astrophysical Journal, 278, 610, 1984)
The Ionization Structure of Planetary Nebulae IV. NGC 6853 (Astrophysical Journal, 284, 589, 1984)
The Ionization Structure of Planetary Nebulae V. NGC 3242 (Astrophysical Journal, 294, 193, 1985)
The Ionization Structure of Planetary Nebulae VI. NGC 7662 (Astrophysical Journal, 308, 314, 1986)
The Ionization Structure of Planetary Nebulae VII. New Observations of the Ring Nebula Astrophysical Journal, 322, 922, 1987)
The Ionization Structure of Planetary Nebulae VIII. NGC 6826 (Astrophysical Journal, 326, 164, 1988)
The Ionization Structure of Planetary Nebulae IX. NGC 1535 (Astrophysical Journal, 340, 921, 1989)
The Ionization Structure of Planetary Nebulae X. NGC 2392 (Astrophysical Journal, 371, 217, 1991)
Discovery of Supernova 1994U in NGC 4948 (International Astronomical Union Circular #6011, June, 1994)
Wheaton’s Quest for Supernovae (Fall, 1994 issue of CCD Astronomy cover story)
Monitoring the Mass Accretion Rate in Sco X-1 Using the Optical Johnson B Filter B.J. McNamara, J. Norwood, T.E. Harrison, R. Dukes, and T. Barker, Ap. J., 623, 1070, 2005
The Case for Third Bodies as the Cause of Period Changes in Selected Algol Systems D.I. Hoffman, T.E. Harrison, B.J. McNamara, W.T. Vestrand, J.A. Holtzman, T. Barker, A.J. 132, 2260, 2007
The Historic Optical Light Curve and 2007 Outburst of Quasar PKS 1749+096 Balonek, Thomas J.; Chromey, F.R.; Barker, T.; Levandowski, K.; Clements, S.D.; Aller, M.F.; Aller, H.D.; Gurwell, M.A. American Astronomical Society, AAS Meeting #211, #04.17, January 7, 2008
The Monitoring of Transient Lunar Phenomena
Doorn, Jarrel; Eaton, M.; Ahrendts, G.; Barker, T.
American Astronomical Society, AAS Meeting #218, #224.06; Bulletin of the American Astronomical Society, Vol. 43, 2011
Rotation Period Determination for 180 Garumna: A Triumph of Global Collaboration
Pilcher, Frederick; Benishek, Vladimir, Delos, Shelby; Barker, Timothy; Ahrendts, Gary; Hamanowa, Hiromi; Hamanowa, Hiroko; Higgins, David
The Minor Planet Bulletin (ISSN 1052-8091). Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers, Vol. 39, No. 2, p. 46 (2012) Light Curve of Minor Planet 1026 Ingrid
Delos, S.; Ahrendts, G.; Barker, T.
The Journal of the American Association of Variable Star Observers, vol. 40, no. 1, p. 423
Rotation Period Determination for 247 Eukrate
Pilcher, Frederick; Delos, Shelby; Ahrendts, Gary; Barker, Timothy
The Minor Planet Bulletin (ISSN 1052-8091). Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers, Vol. 39, No. 4, p. 204 (2012)
Teaching Interests
I’d like to see every Wheaton student take at least one astronomy course, and I’m delighted that so many do take astronomy. Many beginning students believe that they are weak in science, and I enjoy helping them to discover that they can be very good at astronomy and can find the subject exciting. All astronomy courses taught at Wheaton are now at least partially Web-based, and one, The Universe, is an entire self-contained text. The goal of this Web-based approach is to help students learn better and faster outside class, so that more class time can be spent discussing and “uncovering” the material, rather than just covering it. I’ve travelled to Mexico and Guatemala several times to study Maya astronomy, and I teach a course “Ancient Astronomies” that focuses on Maya and Islamic astronomy.
Student Projects
Funded by a NASA grant, students are monitoring the moon to look for transient phenomena. Several students and I presented a paper at the May 2011 American Astronomical Society about this ongoing project.
Using our telescope in Australia (controlled over the Internet), students and I have measured the light curve of three minor planets. The results for 1026 Ingrid were presented at a meeting of the American Association of Variable Star Observers. Light curves for 180 Garumna and 247 Eukrate were obtained in collaboration with observers in New Mexico and several other countries and have been published in the Minor Planet Bulletin.
Students have used telescopes at Wheaton and in Australia to monitor a quasar in collaboration with several other institutions, and the results presented at an American Astronomical Society meeting. Recent senior theses include: a theoretical study of light curves, an analysis of the college-owned spectrometer, a theoretical and observational study of Delta Scuti stars, and modeling the change in the size of the habitable zone as the Sun evolves off the main sequence.
Research Interests
I have observed extensively with the large telescopes at Kitt Peak National Observatory and with NASA’s International Explorer Satellite, studying planetary nebulae (the material left behind by stars when they die), but my main research interests have shifted to projects that can be done using the equipment on the Observing Deck on the roof of the Science Center. Using one of these telescopes, we became the first liberal arts college in the country to discover a supernova, 1994U. We now have a total of nine computerized telescopes, seven of which are equipped with superb CCD cameras. Although the primary purpose of these telescopes is to give all introductory students the chance to use modern astronomical equipment, we also use them to study eclipsing binary stars, cataclysmic variable stars, X-ray variables, and quasars. Our satellite-tracking telescope allows us to study satellites and space debris. Students also use our telescope at the Wheaton College Observatory at Grove Creek, Australia, which is controlled over the Internet.
