Astro-2 Public Affairs Status Report #16 6:00 p.m. CST (7/17:22 MET), March 9, 1995 Spacelab Mission Operations Control Marshall Space Flight Center Huntsville, Ala. The Astro-2 observatory teamed up with NASA's Hubble Space Telescope today for a close examination of the planet Jupiter's "northern lights." Though Jupiter is always in daylight from Earth's perspective, ultraviolet photographs reveal a glowing circle of charged particles in its upper atmosphere, comparable to the beautiful aurora borealis visible in our far northern latitudes. Payload Specialist Sam Durrance, whose astronomical specialty is Jupiter, carefully centered the Hopkins Ultraviolet Telescope's (HUT) view on the northern region of the planet. The Astro telescopes made high-quality spectral and polarimetric measurements, as well as wide-field, far- ultraviolet images. At the same time, Hubble's Wide Field/Planetary Camera 2 obtained high resolution, far-ultraviolet images of the auroral region. Dr. Paul Feldman, professor of physics at The Johns Hopkins University, is the lead scientist for both the HUT and Hubble observations. "We're very interested in whether the recent volcanic eruption on Jupiter's moon Io produced more ions in the planet's magnetosphere and led to a brighter aurora. There is some debate as to whether atmospheric ionization in the Jovian system is created primarily by sunlight, as it is in Earth's atmosphere, or by volcanic activity on Io," said Feldman. "We obtained a very nice spectrum of molecular hydrogen, the dominant component of Jupiter's upper atmosphere, which we will analyze in correlation with the Hubble images. By combining the two, we will get a scientific product that is greater than the sum of the two individual observations." Several of today's observations were for scientific programs designed by Astro-2 guest investigators. As mission planning began, NASA invited astronomers to suggest experiments and observations that could be conducted using one or more of the ultraviolet telescopes. A committee of astronomers reviewed the proposals and selected ten to be included in the observation schedule. Dr. John Raymond, of the Smithsonian Institution Astrophysical Observatory, used the Hopkins telescope to view two supernova remnants, the Cygnus Loop and Vela F. Both are relatively nearby, with little foreground matter to block a clear view. Raymond is studying the products of supernova explosions -- outwardly moving shock waves containing more energy than most galaxies radiate in a year. As the shock wave and debris from the explosion moves outward, it heats the interstellar medium in its path and may trigger the formation of new stars rich with the elements ejected in the explosion. Scattered long ago by these immense blasts, some of the iron and other heavy elements helped form the world in which we live. Dr. Claus Leitherer, from the Space Telescope Science Institute, took spectral measurements of the starburst galaxy 1050+40, one where rapid star formation is taking place. Leitherer's colleague, Dr. Nolan Walborn, viewed O-type star SK-61837 in the Large Magellanic Cloud, the nearest galaxy to our own Milky Way. Walborn is studying O stars, the hottest and most massive of the "normal" stars, in a far-ultraviolet portion of the spectrum where they had not been studies previously. Both Leitherer and Walborn used the Hopkins telescope for their investigations. Guest Investigator Dr. Gregory Bothun, of the University of Oregon, used the Ultraviolet Imaging Telescope (UIT) to observe galaxy VCC 530, one of a recently recognized class of astronomical objects. "They are called "low- surface-brightness" galaxies because they are fainter than the dark night sky. It has only been in recent years, with improvements in telescopes, that we have been able to detect them," said Dr. Barry Madore, another UIT guest investigator. "The most fascinating thing about this class of galaxies is that ground-based observations show some of them are blue. This could be due to an absence of dust, or because they are made up of very metal-poor stars, or maybe they are a new type we're not been aware of before. By viewing them in ultraviolet light, we can get a better understanding of where they came from and what their properties are." UIT Principal Investigator Ted Stecher, of the Goddard Space Flight Center, chose a cluster of galaxies known as Abell 1367 for observation. The galaxies in this cluster are primarily spirals, like our own Milky Way. Examining photographs of spiral-rich clusters gives astronomers a better understanding of the spatial structure and development of spiral galaxies. UIT made images of Abell 1367 during Astro 1 as well. Stecher also selected NGC 6946, a rapid- star-formation galaxy. Ultraviolet radiation emphasizes the hot stars and dust features associated with spiral arms and suppresses the cool star background of the galactic bulge and underlying disc. Other observations today spanned the life cycle of stars, from studies of the elderly Schweizer-Middleditch white dwarf star to another search for intergalactic helium left over from the birth of the universe. The Astro telescopes are currently in the midst of a nearly four-hour-long observation series to study the magnetic cataclysmic variable binary star, AM Herculis. Tonight's observation schedule gathers more information for studies already in progress: white dwarf stars, hot main sequence stars, cataclysmic variables, globular and open star clusters, Seyfert galaxies, the search for intergalactic helium, and another observation of Jupiter. To follow the mission in progress, visit Astro-2's home page on the Internet World Wide Web: URL "http://astro-2.msfc.nasa.gov"