The Pico Velata telescope (30 meters in diameter).

© IRAM

Perched at 2,850 meters of altitude, on Pico Velata in the Sierra Nevada range near Grenada, Spain, IRAM's 30-meter telescope is the largest antenna operating between 1 and 3 millimeters of wavelength in the world. The Pico Velata telescope is particularly well-suited to map large-area sources as well as those of weak intensity. It has contributed to the discovery of some twenty interstellar molecules, including several free radicals such as C₈Hs and MgNC, that were not observed in earthbound laboratories. This facility has also uncovered molecules in comets, planets, and in Io and Titan, the moons of Jupiter and Saturn. When the comet Shoemaker-Levy collided with Jupiter, Pico Velata was able to observe the formation of CO, HCN, and CS resulting from the impact and to track these molecules' expansion in the planet's upper atmosphere. It has also started the study of the cold dust in the nearby galaxies, as in the most remote ones.

IRAM's interferometer on Plateau de Bure, 2,550 meters high in France's southern  Alps, is composed of six antennas each 15 meters in diameter, which can be moved along two perpendicular rail tracks, each 400 meters long. The large collective area, combined with the high-precision surface, makes it the most sensitive millimeter instrument in the world. It has made possible the systematic study of dust and molecular gas in high-redshift objects (meaning in objects pertaining to the young Universe). It is the only instrument to have detected the CO molecule in thirty or so galaxies and quasars whith redshifts z > 1, like BR 1202 (z=4.69) and J1148+5251 (z=6,42), the farthest molecular sources discovered to date. These observations deliver precious information on the dynamics, mass, and chemical composition (in some cases even on the isotopic composition) of galaxies when the Universe was just one-tenth or one-twentieth of its current age.

With the Bure interferometer astronomers can map even weak sources to a degree of resolution equal to that of the best ground-based optical telescopes, making it the instrument of choice for studying the formation of stars and planetary systems. The accretion and rejection activities associated with star formation can reach spectacular degrees of energy, with collimated gaseous jets and thin disks ringing the young star. The Bure interferometer is the only instrument currently capable of mapping these disks and jets in molecules other than CO, which in turn means that it can record the mass and chemical composition of celestial objects that are in many ways similar to the remains of the solar nebula just after the formation of the Sun.