60 



Annals of the Smithsonian Institution 2000 



Special laboratories are maintained for the petrologic and 

 mineralogic studies of meteorites and lunar samples, for the 

 spectroscopy of atoms and molecules, and for the development 

 of instrumentation, including advanced electronic detectors 

 and atomic maser clocks. This year, significant milestones 

 were reached in the development of the Submillimeter Array 

 (SMA) on Mauna Kea: the first successful observations by two 

 telescopes in interferometric mode and the first detection of 

 fringes on a source outside our galaxy. Another major en- 

 deavor — the conversion of the MMT to a single-mirror 

 telescope — saw completion and "first light" in May. 



SAO instrumentation is also operating in space. The 

 first year of observations for both the Chandra X-ray Obser- 

 vatory and the Submillimeter Wave Astronomy Satellite 

 (SWAS) resulted in numerous findings for the astronomical 

 community. Data from Chandra have provided a wealth of 

 spectacular x-ray images of previously "unseen" phenomena; 

 while observations returned by SWAS, which focuses on the 

 process of star formation through study of the chemical com- 

 position of interstellar gas clouds, have led new information 

 of the presence of water in space. SAO scientists have also 

 pursued studies of the Sun by use of the TRACE spacecraft 

 in addition to ongoing investigations with the Ultraviolet 

 Coronagraph Spectrometer (UVCS). 



Further, the Science Education Department conducts 

 several programs designed to improve the teaching of pre- 

 college science and mathematics, partly through the use of 

 examples from astronomy. These programs include the de- 

 velopment of curriculum materials and videos, the training 

 of precollege educators, and programs for public television. 



Numerous facilities serving the general astronomical com- 

 munity are located at the CfA in Cambridge as well. The 

 Institute for Theoretical Atomic and Molecular Physics, es- 

 tablished in 1988 to attact and encourage talented graduate 

 students to enter this field, emphasizes study of fundamental 

 questions in atomic and molecular physics. Other services 

 include the International Astronomical Union's Central 

 Bureau for Astronomical Telegrams and the Minor Planet 

 Center, both of which disseminate information on astronom- 

 ical discoveries worldwide. Also located at the Cambridge 

 site is the gateway for SIMBAD, an international astronomi- 

 cal computer database, as well as Harvard's extensive 

 collection of astronomical photographic plates, the largest in 

 the world. In addition, SAO operates the Astrophysics Data 

 System (ADS) and the Chandra X-ray Observatory Science 

 Center and Operations Control Center, on behalf of NASA. 

 SAO also provides Guest Observer Facilities for investigators 

 using data from the Roentgen X-ray satellite (ROSAT), a 

 joint venture of Germany, the United Kingdom, and the 

 United States. 



Research Highlights 



SAO has the lead role in operating the NASA Chandra X-ray- 

 Observatory, which completed its first year of observations in 

 FY 2000 with a series of widely reported results and discov- 

 eries. Chandra studied the presence of compact X-ray stars in 

 supernova remnants, the galactic center X-ray source, the 



disk and jets in the Crab Nebula, and obtained deep images, 

 which resolve the X-ray background into faint sources. 

 Chandra also found superbubbles of very hot gas within col- 

 liding galaxies, discovered that even small, failed stars emit 

 X-ray flares, found X-rays coming from a comet, and opened 

 a whole new field of research by discovering medium-sized 

 black holes. 



SAO was also the leader of another NASA satellite effort, 

 the Submillimeter Wave Astronomy Satellite (SWAS), a 

 space telescope, which is studying the chemistry of the inter- 

 stellar gas clouds in the Milky Way galaxy. SWAS discovered 

 that water, a key component for life, is prevalent throughout 

 space, and found that a substantial amount of water is pres- 

 ent in the Martian atmosphere, but, surprisingly, SWAS has 

 been unable to find any molecular oxygen beyond Earth. 

 Another SAO program, designed to study our Milky Way 

 galaxy, this year completed its 20-yeaf radio astronomy 

 survey, and released an image of the entire galaxy with un- 

 precedented detail and clarity. 



By observing the transits of a suspected planet in front of 

 the star HD209458, SAO astronomers took a giant step 

 toward learning about the nature of planets outside our solar 

 system — their size, mass, and density. These observations, 

 made initially by a graduate student advisee of an SAO sci- 

 entist, marked the first time that astronomers had directly 

 detected an extrasolar planet, in this case by watching its 

 shadow cross the disk of a Sun-like star. The precise observa- 

 tions allowed astronomers to determine that the suspected 

 planet is a "gas giant," with a density somewhat less than 

 that of Saturn in our own solar system and a size about one 

 third greater than Jupiter's. 



In FY 2000, SAO's solar system astronomers (together 

 with their colleagues) were very active. They discovered two 

 new moons of Jupiter (numbers 17 and 18) and a new moon 

 of Saturn (number 22). Solar scientists used the TRACE 

 spacecraft to watch the Sun as its activity climbed to a peak 

 during the maximum of its approximately 1 i-year solar 

 cycle; they also used the SOHO spacecraft to study the Sun. 

 New models of the solar activity based on these observations 

 promise to help predict storms of charged space particles that 

 often rain down on the Earth, disrupting communications. 



This year a class of objects intermediate in size between 

 stars and planets, called brown dwarfs, was detected in the 

 Orion nebula. In related work, some very newly formed stars 

 were observed in the process of collapsing, and other young 

 stars were found to have disks or rings of material around 

 them, with compositions likely resembling that of our own 

 solar system at the time of its formation. 



SAO scientists continued as leaders in the field of cosmol- 

 ogy and the structure of the universe. Especially noteworthy 

 was progress that supports the incredible, recent discovery 

 that the universe may be accelerating its expansion, imply- 

 ing the presence of a repulsive component to gravity. Also, a 

 new technique for calibrating the distances to galaxies was 

 developed this past year, and is being tested. 



The Science Education Department (SED) at CfA contin- 

 ued to host teachers from across the United States at sessions 

 designed to train them in the use of the Department's many 



