Tennessee State University
Center of Excellence in Information Systems
Nashville, Tennessee 37203-3401

This report covers the interval October 1, 2003, through September 30, 2004.

The astrophysics program in the TSU Center of Excellence concentrates on photometry and spectroscopy of cool giants, chromospherically active stars, solar-type stars, planetary-candidate host stars, binary and multiple stars, and pulsating variables, as well as building and managing robotic telescopes, and applying automation to astronomy. Astronomy staff in 2003-04 were Geoffrey S. Burks, Michael R. Busby, Joel A. Eaton, Francis C. Fekel, Gregory W. Henry, and Michael H. Williamson. Williamson was converted from part-time to full-time status and continued working as an instrumentalist and controls expert supporting the automatic spectroscopic telescope and our automated astronomy program in general. Marino Alvarez (Coll. of Education) and Sallie L. Baliunas (CfA) continued as adjunct staff. Frank Alston and Stephen Henry worked as student astronomy research assistants during the academic year. Undergraduate students Christiane Buggs, Amelie Gillman, Sharina Haynes, Julie Henry, Stephen Henry, Tywana Lampkin, Gerald Onuoha, Brittney Smith, Brian Taylor, Tanisha Taylor, and Jerry Washington worked with Burks, Fekel, and Henry on various research projects in the JPL Summer Navigator Project.

1 OBSERVING FACILITIES

Center of Excellence astronomers operate several automatic telescopes at Fairborn Observatory in the Patagonia mountains of southern Arizona. Fairborn is a non-profit Educational Corporation directed by Lou Boyd and dedicated to the advancement of automated astronomy. Operational telescopes include the T2 0.25 m automatic photoelectric telescope (APT) for Johnson VRI photometry, the T3 0.40 m APT for Johnson BV photometry, the T4 0.75 m APT for Stromgren by photometry, the T8, T10, T11, and T12 0.80 m APTs, also for Stromgren by photometry, and the T13 2.0 m automatic spectroscopic telescope (AST) for high-resolution echelle spectroscopy.

During the most recent observing year (2003 September - 2004 July), the T2 0.25 m APT collected 8045 group observations during 232 nights, mostly of the unusual Be variable star Gamma Cas and approximately three dozen young, solar-type stars from one of the Spitzer Space Telescope Legacy Projects. In 16 years of operation, the T2 APT has collected 102,658 group observations of variable stars. The T3 0.40 m APT collected 16,313 group observations, primarily of chromospherically active binary and single stars and Gamma Doradus candidates, on 257 nights. In its 17 years of operation, it has collected 230,978 group observations. The T4 0.75 m APT acquired 7,026 group observations of solar-type stars on 253 nights. It has collected a total of 60,687 group observations in 12 years of operation. The T8 0.80 m APT made 10,070 group observations of solar-type stars on 241 nights. In 9 years of operation, it has collected a total of 61,964 group observations. The T10 0.80 m APT made a total of 10,287 group observations of solar-type stars on 253 nights. In 4 years of operation, it has collected a total of 37,555 group observations. The T11 0.80 m APT made a total of 10,287 group observations of solar-type stars on 254 nights. In 4 years of operation, it has collected a total of 35,415 group observations. The T12 0.80 m APT made a total of 12,239 group observations of planetary-candidate stars on 250 nights. In its 4 years of operation, it has collected a total of 37,255 group observations. Finally, in its first full year of operation, the T13 2.0 m AST collected 9480 high-dispersion echelle spectra on 252 nights, mostly of cool giant stars. Initial programs running on the AST include orbits of long-period binaries, changes in winds and chromospheres of cool stars, and Doppler imaging of IM Peg for the Gravity Probe B mission. Further information about the APTs and the AST can be found on the Web at http://schwab.tsuniv.edu and http://astro.tsuniv.edu, respectively.

2 RESEARCH

2.1 Automatic Telescopes

Eaton and Williamson presented two papers about the development of the TSU 2.0 m AST at the International Society for Optical Engineering (SPIE) Astronomical Telescopes and Instrumentation 2004 Symposium in Glasgow, Scotland and at the Third Potsdam Thinkshop on Robotic Astronomy in Potsdam, Germany.

Eaton and Williamson have perfected a system for washing the mirror using paint sprayers to flood it with detergent and water followed by drying with an air stream. They have also finished the data logging system for the AST.

2.2 Binary and Multiple Stars

Fekel, in collaboration with C. Scarfe (Univ. of Victoria) and others, is continuing spectroscopic observation of about 20 close multiple systems and a half dozen speckle binaries to obtain fundamental parameters. For most of the systems, speckle observations have been obtained by the CHARA group (Georgia State Univ.) and the USNO.

For over a decade, Fekel has monitored the radial velocities of about 30 slowly rotating B and A stars, which are candidates for early-type velocity standards. A bootstrap procedure has been used to tie the velocities of the early-type stars to the IAU late-type velocity system. Most of the early- and mid-B type stars have variable velocities. However, about two-thirds of the slowly rotating late-B and A-type stars appear to have constant velocities.

Fekel and Tomkin (Univ. of Texas) are obtaining spectra of 34 known spectroscopic binaries with orbital periods greater than 5 days. Such stars are likely targets of various optical interferometers that are now in operation. The new radial velocities will be used to determine significantly improved orbital elements so that good three-dimensional orbital solutions can eventually be determined. Lines of the secondary star have been detected for seven single-lined binaries, turning those systems into the more useful double-lined variety. Fekel presented the current status of this research at the Third Potsdam Thinkshop on Robotic Astronomy in Potsdam, Germany.

Fekel, in collaboration with K. Hinkle (NOAO), R. Joyce (NOAO) and P. Wood (Australian National Univ.), continued a program of high-resolution infrared spectroscopy to obtain orbital elements of over 50 southern symbiotic binaries. This survey will greatly supplement our recent results for 15 systems observed from the northern hemisphere. Since currently there are fewer than 24 symbiotic systems with well-determined orbital elements, the results from this observing program will provide statistics on a greatly expanded sample of symbiotic binaries. To date, the observations indicate that the vast majority of southern symbiotics have orbital periods of at least 500 days. Because of the loss of Mt. Stromlo Observatory, where our program was begun, we are currently observing a subset of our southern symbiotic stars at Kitt Peak National Observatory with the coude feed telescope.

Henry and Fekel with J. Sowell (Georgia Tech Univ.) and J. Gearhart (Georgia Tech Univ.) have obtained and analyzed photometry and spectroscopy of HD 71636, a T3 photometric comparison star discovered to be an eclipsing binary. It is a detached system with a period of 5.013 days that consists of two F-type stars on the main sequence.

Fekel and summer students Buggs, Onuoha, and Smith determined an orbit for HR 1613, a single-lined binary with a very small mass function. This narrow-lined A9 IV star has a period of 8.1114 days and a circular orbit. Its unseen secondary is likely an M dwarf.

2.3 Chromospherically Active Stars

Fekel and Henry have determined improved orbits for three chromospherically active, single-lined spectroscopic binaries, HD 37824, HD 181809, and HD 217188. The primary components of HD 181809 and HD 217188 are likely first ascent giants, while that of HD 37824 is probably in the core-helium burning evolutionary stage. Photometry shows that all three stars have long-term variations in mean brightness and photometric amplitude, but no correlations were found. There is no clear evidence of long-term, periodic variations.

Henry and V. Aarum-Ulvas (Astrophysical Institute of Potsdam) have submitted a paper to Astronomische Nachrichten containing their analysis of color changes in the chromospherically active binaries V711 Tau and RS CVn. Most chromospherically active binary stars become fainter and redder as large starspots rotate into view on the stellar disk. However, some of the most active systems such as UX Ari become bluer as they get fainter. Henry and Aarum-Ulvas have been analyzing the extensive T3 APT data base on several dozen chromospherically active binaries looking for additional examples. In the case of V711 Tau and RS CVn, it appears that the flux of their companion stars is insufficient to explain the color changes. Preliminary modelling suggests that hot, bright, photospheric facular regions accompanying the cool, dark spots on the active component may provide the explanation. Results of this work were also presented at the Cool Stars 13 Workshop in Hamburg, Germany.

Henry and Eaton have been making photometric and spectroscopic observations of the chromospherically active binary IM Peg with the T2 and T3 APTs and the T13 AST in support of the Gravity Probe B mission, successfully launched in April. The GP-B satellite is using IM Peg as its guide star to establish the inertial reference frame for its relativity experiment. Henry made additional manual photometric observations with a Meade 10-inch LX200 telescope and Optec SSP3 photometer during the summer shutdown of the Fairborn telescopes. The photometric and spectroscopic observations will be used to derive Doppler images, in collaboration with S. Berdyugina (Institut fur Astronomie, Zurich), that will aid in the interpretation of the GP-B results.

2.4 Education

Burks is continuing work on the TSU streaming video astronomy course to be delivered under a NASA NRTS grant. The primary audience consists of students at colleges without an astronomy course. Filming, post-production, and testing are continuing. An automated telescope for education has been placed at Vanderbilt University's Dyer Observatory; testing is expected to occur during the final months of 2004.

2.5 Extrasolar Planets

Henry is continuing to obtain photometry of the host stars of extrasolar planetary systems to search for additional planetary transits of bright stars and to confirm new planetary candidates, primarily in collaboration with the planet-search group led by G. Marcy (Univ. of California). A paper by Marcy et al. has been accepted for the Astrophysical Journal announcing five new extrasolar planets around nearby G and K stars with minimum masses ranging between 0.1 and 3.7 M_JUP and orbital periods between 17 days and 7.2 years. A second paper by P. Butler (Carnegie Institute of Washington) et al. has been accepted for the Astrophysical Journal that describes the discovery of a very low mass extrasolar planet around the M2.5V star GJ 436. The minimum mass of the planet is 0.067 M_JUP = 1.2 M_NEP = 21 M_EARTH, making it the first extrasolar planet to be discovered in the Neptune mass domain. This low mass implies the possibility of ice/rock or rock composition. Sadly, the APT observations ruled out photometric transits of this planet, even for the smaller radii corresponding to solid compositions, so its nature remains unknown. A third paper by Vogt (Univ. of California at Santa Cruz) et al. is in final preparation and will announce several new systems with at least two planets.

Henry has made new Stromgren by observations of the transits of HD 209458b with the T10 APT. These observations are being combined by R. Wittenmyer (Univ. of Texas) and others with previous Hubble Space Telescope STIS and FGS photometry, new and existing Keck/HIRES radial velocities, and additional photometry from Mt. Laguna Observatory to derive improved parameters for this system. The radius of the planet is determined to be 1.357 R_JUP with an uncertainty of 0.013 R_JUP, confirming the need for irradiation and/or some other source of energy to explain the large radius. A paper is nearing completion for the Astrophysical Journal.

S. Henry has written and extensively tested software to search for planetary transits in the APT photometry on solar-type stars. The software is based on a method by G. Laughlin (Univ. of California at Santa Cruz) using a chi-squared statistic to search for periodic small dips in the brightness of a star. To test the program's capability, simulated transits were added to actual APT data sets, which were then searched by the new software. Due to the high precision of our typical APT data sets (0.001-0.002 mag), transits of a 0.5 R_JUP planet across a 1.0 solar radius star (resulting in a transit depth of only 0.0027 mag) were recovered in 80% of the trials for periods between 3 and 10 days. Thus, we are sensitive to transits of possible short-period Neptune-mass planets that likely would have escaped detection by current radial velocity techniques. S. Henry has been analyzing the T4, T10, and T11 data sets on solar-type stars. He also supervised summer students Gillman, Lampkin, B. Taylor, and Washington as they analyzed the data from the T8 APT. Analysis of all the solar-type star data is now nearing completion, and no convincing new transit candidates have emerged. However, grazing eclipses only a few millimags deep were discovered in two photometric comparison stars. A paper is planned to illustrate the capabilities of the technique and to place limits on the number of Neptune-mass planets in short-period orbits around solar-type stars.

Henry completed a two-year campaign in July with the T12 APT to monitor 93 young solar-type stars (ages 3 Myr to 3 Gyr) that are part of the Spitzer Space Telescope (SST) Legacy Science Project "The Formation and Evolution of Planetary Systems: Placing Our Solar System in Context." SST is studing the evolution of planetary systems around these stars by observing their dust disks. Marcy is using the 10 m Keck telescope to make precise radial velocity observations of these 93 stars to search for young planetary systems. The APT observations complement the SST and Keck observations by measuring the level of starspot activity in these stars and, in the majority of cases, determining their rotation periods directly. This will allow the radial velocity variations induced by planetary companions in these young systems to be disentangled from the confusing effects of stellar activity and increase the confidence in any detected planetary systems. Henry and Alston analyzed the first year of observations and presented the results at the 203rd meeting of the American Astronomical Society. Henry and Gillman will complete the analysis of the whole data set in the coming months.

Henry has joined a new collaboration, called the N2K (Next 2000 Stars) Consortium, consisting of the California planet-search group and additional researchers from the Space Telescope Science Institute, Japan, and Chile. The N2K Consortium is using the Keck, Magellan, and Subaru telescopes to search for short-period gas giant planets around a new sample of 2000 F-M metal-rich main sequence and subgiant stars brighter than V = 10.5. Over 40 stars with short-term radial velocity variability have already been identified. Henry is observing them with the APTs to look for brightness changes, which could implicate stellar activity as the cause of the radial velocity variations, and to search for planetary transits. A paper by Fischer (San Francisco State Univ.) et al. describing the N2K Consortium has been accepted for the Astrophysical Journal. The paper also announces the first planetary discovery from the N2K sample, a Saturn-mass planet in a 3.41-day orbit around the G5IV star HD 88133. The APT observations reveal no brightness variability on the orbital period to a limit of 0.0005 mag. Despite a transit probability of 15.6%, the APT photometry rules out shallow transits predicted by the large stellar radius.

2.6 Gamma Doradus Stars

Henry and Fekel are conducting further photometric and spectroscopic observations with the T3 APT and the KPNO coude feed telescope in search of new Gamma Doradus variables. A paper by Henry and Fekel published in the Astronomical Journal for December 2003 described 12 new Gamma Doradus stars and brought the number of confirmed Gamma Doradus stars to 42. This year, an analysis was completed of another 11 candidates from the lists of G. Handler (Univ. of Vienna), and all 11 were confirmed as new Gamma Doradus variables. These results are being prepared for the Astronomical Journal. Seventeen new candidates from the one year survey of 275 Gamma Doradus candidates conducted with the T12 APT in 2001-002 are being extensively observed this year with the T3 APT and at KPNO.

Henry, Fekel, and S. Henry published a paper in the Astronomical Journal for March 2004 describing their observations of HD 207651, a star once suspected of having both Delta Scuti and Gamma Doradus pulsations. Their results demonstrated that its low-frequency variability is due to ellispoidal variation in a close binary and not Gamma Doradus pulsation. They argued, from the statistics of Gamma Doradus stars that also lie within the Delta Scuti instability strip but do not show Delta Scuti variability, that it is unlikely the two types of pulsation can coexist in the same star.

Despite the findings reported in the previous paragraph, Henry and Fekel have discovered the first case of instrinsic Delta Scuti and Gamma Doradus pulsations in the same star: HD 8801 = HR 418. HD 8801 is also a metallic-line Am star with no hint of radial velocity variability due to orbital motion. Since the vast majority of Am stars are members of binary systems with periods less than 1000 days and also do not pulsate, HD 8801 possesses a unique combination of physical properties. Henry and Fekel found six independent pulsation periods between 0.048 and 0.404 days. The star's projected rotational velocity of 55 km s^-1 is typical for Am stars, which, as a group, rotate more slowly than normal A stars. HD 8801's slow rotation compared to the normal A stars does not appear to arise from either a binary companion or evolutionary expansion and so is a puzzle. Henry and Fekel have submitted their findings to the Astronomical Journal.

2.7 Long-Period Variables

Fekel, T. Lebzelter (Univ. of Vienna), Hinkle, Joyce, and Wood have finished a radial velocity study of bright, southern, long-period variables. The objects follow the period-luminosity relations determined for such variables in the Large Magellanic Cloud. All miras fall on the fundamental mode sequence while the semi-regular variables fall on both the first overtone and fundamental mode sequences. For fundamental mode pulsators, the velocity amplitude shows a correlation with light amplitude.

2.8 Solar-Type Stars

Henry, Fekel, and S. Henry are continuing their long-term study of photometric variations in a large sample of solar-type stars, described in last year's report. The T3, T4, and T8 stellar sub-samples have now been observed for 7 to 12 years, while the stars on T10 and T11 have been monitored for three or four years. An unfortunate development this year was the termination of the Mount Wilson HK Project, conducted for many years by Baliunas and R. Donahue (CfA), which was providing contemporaneous Ca II H & K observations of our sample of solar-type stars. Henry presented a review of the program at The Next Decade of Stellar Cycles Research workshop at Lowell Observatory in October.

Ca II H & K measurements for a subsample of the solar-type stars are continuing in the Solar-Stellar Spectrograph (SSS) project at Lowell Observatory by W. Lockwood and J. Hall. With the closure of the HK Project at Mount Wilson, Henry, Lockwood, and Hall are working to realign the APT and SSS observing programs to observe as many stars in common as possible.

Henry, Fekel, and S. Henry, along with Baliunas, Lockwood, and R. Radick (Air Force Research Laboratory) have completed the analysis of the available photometric and H & K data sets on 30 of the APT stars that were also observed in the HK Project and in the earlier Lowell solar-type star project. The combined photometric time series on these stars now extend for up to 20 years, while the H & K data sets are even longer for many stars. The results of this analysis are being prepared for publication in the Astrophysical Journal. Progress reports were presented at the 204th meeting of the American Astronomical Society in Denver and at the First International Symposium on Space Climate in Oulu, Finland.

Henry collaborated with K. Biazzo (Univ. of Catania), A. Frasca (Catania Observatory), S. Catalano (Catania Observatory), and E. Marilli (Catania Observatory) to compare brightness changes in several young, single, solar-type stars with temperature variations and the presence of chromospheric plage regions derived from spectroscopic line-depth ratios and H-alpha equivalent widths. Strong correlations between brightness and effective temperature as well as anti-correlations between brightness and H-alpha emission suggest close spatial association of spots and plages in young main-sequence stars. Results were presented at the Cool Stars 13 Workshop in Hamburg, Germany.

Henry, Burks, and T. Gary (TSU CoE) worked with TSU students T. Taylor, Haynes, and J. Henry on a project to compare the history of brightness variability in the Sun, as deduced from the APT observations of 350 solar-type stars, with the progression of life on Earth, as deduced from the geological record. Of particular interest was the demonstration that the Cambrian explosion on Earth did not occur until the Sun's brightness variability had decreased to less than 1% of its youthful value. This result has obvious implications for the search for complex life in other planetary systems. Taylor presented results of this comparison at the Astrobiology Science Conference 2004 at the NASA Ames Research Center in March. During the summer JPL Navigator program, the students investigated the survival abilities of various primitive extremophile organisms, including E. Coli, yeast cells, and Tardigrades (Water Bears), by irradiating them with ultraviolet light at flux levels expected during the Pre-Cambrian era on Earth.

2.9 Miscellaneous

Henry has been extensively observing the Be star Gamma Cas with the T2 and T3 APTs in collaboration with M. Smith (Computer Sciences Corporation) and R. Robinson (Catholic Univ. of America). They have been awarded 116 ksec of observing time with the Rossi X-ray Timing Explorer (RXTE) satellite to make simultaneous optical and X-ray observations and understand the origin of the correlated optical and X-ray variations.

PUBLICATIONS

Alston, F., Henry, G. W., & Burks, G. S. 2003, "A Photometric Survey of 93 Young Planetary-Candidate Stars," BAAS, 35, 1235

Burks, G. S. 2003, "The TSU Streaming Video Astronomy Course I, Course Content," BAAS, 35, 1238

Eaton, J. A., & Williamson, M. H. 2004, "Managing the Operations of the TSU 2-m Automatic Spectroscopic Telescope," Astronomische Nachrichten 325, 522

Eaton, J. A., & Williamson, M. H. 2004, "Control of the TSU 2-m Automatic Telescope," in Advanced Software, Control, and Communication Systems for Astronomy, SPIE 5496, eds. H. Lewis & G. Raffi (SPIE: Bellingham, WA), p. 710

Fekel, F. C. 2004, "Chromospherically Active Stars. XXIII. The Triple System HD 7205 = QU Andromedae," AJ, 127, 2931

Fekel, F. C. 2004, "The Spectroscopic Orbit of Phi Cygni, a System with Two Late-Type Giants," Revista Mexicana de Astronomia y Astrofisica 21, 63

Fekel, F. C. 2004, "Increased Multiplicity of 77 Cyg, V815 Her, and HD 140122," Revista Mexicana de Astronomia y Astrofisica 21, 45

Fekel, F. C., Henry, G. W., & Alston, F. M. 2004, "Chromospherically Active Stars. XXII. HD 18955, A Massive K Dwarf Binary," AJ, 127, 2303

Fekel, F. C., Hinkle, K. H., & Joyce, R. R. 2003, "Rotational Velocities of Symbiotic Stars," in Symbiotic Stars Probing Stellar Evolution, ASP Conf. Ser. 303, eds. R. L. M. Corradi, J. Mikolajewska, & T. J. Mahoney (San Francisco: ASP), p. 113

Fekel, F. C., Hinkle, K. H., Joyce, R. R., & Lebzelter, T. 2003, "Velocity Observations of Multiple Mode AGB Variable Stars," in Proceedings of the 12th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, eds. A. Brown, G. M. Harper, & T. Ayres, http://origins.colorado.edu/cs12/, p. 1069

Fekel, F. C., & Tomkin, J. 2004, "Spectroscopic Orbits of Potential Interferometric Binaries," Astronomische Nachrichten, 325, 649

Henry, G. W., & Fekel, F. C. 2003, "A Dozen New Gamma Doradus Stars," AJ, 126, 3058

Henry, G. W., Fekel, F. C., & Henry, S. M. 2004, "HD 207651: A Triple System with Delta Scuti and Ellipsoidal Variations But No Gamma Doradus Pulsations," AJ, 127, 1720

Hinkle, K. H., Joyce, R. R., Fekel, F. C., Wood, P. R., & Skrutskie, M. F. 2003, "Infrared Velocities of Symbiotic Stars," in Symbiotic Stars Probing Stellar Evolution, ASP Conf. Ser. 303, eds. R. L. M. Corradi, J. Mikolajewska, & T. J. Mahoney (San Francisco: ASP), p. 129

Lockwood, G. W., Radick, R. R., Henry, G. W., & Baliunas, S. L. 2004, "A Comparison of Solar Irradiance Variations with Those of Similar Stars," BAAS, 36, 671

Paulson, D. B., Saar, S. H., Cochran, W. D., & Henry, G. W. 2004, "Searching for Planets in the Hyades III: The Quest for Short-Period Planets," AJ, 127, 1644

Percy, J. R., Bakos, A. G., Besla, G., Hou, D., Velocci, V., & Henry, G. W. 2004, "Multiperiodicity in Pulsating Red Giants," in Variable Stars in the Local Group, ASP Conf. Ser. 310, eds. D. W. Kurtz & K. R. Pollard (San Francisco: ASP), p. 348

Pourbaix, D., Tokovinin, A. A., Batten, A. H., Fekel, F. C., Hartkopf, W. I., Levato, H., Morrell, N. I., Torres, G., & Udry, S. 2004, "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits," A&A, 424, 727

Schultz, A. B., Kinzel, W., Kochte, M., Jordan, I. J. E., Hamilton, F., Henry, G., Vogt, S., Bruhweiler, F., Storrs, A., Hart, H. M., Bennum, D., Rassuchine, J., Rodrigue, M., Hamilton, D. P., Welsh, W. F., & Taylor, D. C. 2004, "HST/FGS Photometry of Planetary Transits of HD 209458," in The Search for Other Worlds: Fourteenth Astrophysics Conference, AIP Conf. Proc. 713, ed. S. S. Holt & D. Deming, p. 161

Taylor, T., Henry, G., Gary, T., & Burks, G. 2004, "Solar Brightness Variability and the Evolution of Life on Earth," International Journal of Astrobiology, Volume 3, Issue 1, Supplement, 46

Welsh, W. F., Schultz, A. B., Kinzel, W., Kochte, M., Jordan, I., Hamilton, F., Bruhweiler, F., Hart, H., Hamilton, D. P., Henry, G., Miskey, C., Rodrigue, M., Bennum, D., Rassuchine, J., Storrs, A., & Vogt, S. 2004, "HST/FGS High-Speed Photometric Observations of Transits of HD 209458b, in Bioastronomy 2002: Life Among the Stars, IAU Symp. Proc. 213, ed. R. Norris & F. Stootman (San Francisco: ASP), p. 89