Number 255, January 19, 1996 by Phillip F. Schewe and Ben Stein WATERWORLD: NEW EXTRASOLAR PLANETS HAVE BEEN DISCOVERED , and they might support liquid water. Scientists discussing the new observations at this week's meeting of the American Astronomical Society in San Antonio, Texas sense that with solar systems other than our own available for inspection, a new era in astronomy is opening up. This study of regular planets orbiting sun-like stars (planets around pulsars were detected a few years ago) began only in October 1995 with the discovery of a planet around the star 51 Pegasi (Update 246). That planet orbits its star at a radius of only 0.05 AU (an astronomical unit is the distance between Earth and sun), making it very hot (1000 C) and inhospitable for life. Geoffrey Marcy of San Francisco State announced at the AAS meeting the discovery of two planets, both about 35 light years from Earth. One orbits the star 70 Virginis at a distance of 0.43 AU with a period of 116 days; it has a mass of about 8 or 9 Jupiters and a surface temperature of about 83 C (185 F). Liquid water and conceivably life forms could be sustained at such a planet or on a nearby moon, Marcy said. The other planet orbits the star 47 Ursae Majoris at a distance of 2.1 AU with a period of 1100 days. It has an estimated mass of 3.5 Jupiters and a surface temperature of -90 C. Marcy notes that some zones in the planet's atmosphere could harbor liquid water. Marcy hinted that his long-term study of 120 nearby stars, carried out at the Lick Observatory, would soon yield more planets. Basically, his evidence for planets consists of slight modulations in the light coming from the stars as a result of the tug between planet and star. Meanwhile, Christopher Burrows of the Space Telescope Science Institute reported that the star Beta Pictoris, whose circumstellar dust disk has long been thought of as a possible nursery for planets, did in fact possess a Jupiter-sized planet. The evidence for this, he argued, was a warping of the inner part of the dust disk caused by the tidal effects of a presumed planet orbiting in the clear zone between the star and the inner edge of the dust disk. THE HUBBLE DEEP FIELD (HDF) , a picture of a tiny patch of sky taken by the Hubble Space Telescope, is the deepest optical image of the universe ever recorded. Actually, it would be more accurate to say that the HDF has captured the faintest galaxies (down to an unprecedented 30th magnitude) rather than the deepest or furthest galaxies because the distances to many of the objects are not yet known. Still, if as expected deepness goes with faintness and if thereby the image serves partly as a snapshot of the universe at a very early time in its history, then it is significant that the density of galaxies in the field is quite high; an estimated 1500 of all types and shapes crowd the frame. This would suggest that telescopically astronomers had not yet glimpsed the epoch of the first galaxies. The observations were carried out over a ten- day period in December 1995 and used four wavelength bands in order to achieve a true color image. THE FIRST DIRECT IMAGE OF THE SURFACE OF A STAR other than our sun was reported by Andrea Dupree of Harvard- Smithsonian. The surface of the star, Betelgeuse, had been indirectly imaged earlier using speckle interferometry, in which many brief exposures are added up to make a composite image. Dupree's pictures, made with the Hubble Space Telescope, confirm previous suspicions that Betelgeuse's surface exhibits a giant bright spot. According to Dupree, the spot is 2000 K warmer than its surroundings and this might be indicative of a new physical phenomenon at work in some stellar atmospheres.