A new and uniquely powerful tool for cutting-edge science is emerging on the crisp, high desert of western New Mexico. Outwardly, it looks much the same as the famed Very Large Array (VLA), a radio telescope that has spent more than 3 decades on the frontiers of astronomical research. The 27 white, 230-ton dish antennas still peer skyward, the 72 miles (116 kilometers) of railroad track still wait to transport the antennas across the arid plains, the familiar buildings remain, and crews still fan out across the desert to service the antennas.
Functionally, however, everything has changed. The VLA has become the Expanded VLA (EVLA).
"We have a completely new scientific instrument, with completely new capabilities, and it's enabling research that was impossible until now," said Chris Carilli, chief scientist of the National Radio Astronomy Observatory (NRAO). Carilli and Rick Perley, EVLA project scientist, outlined the capabilities and early accomplishments of the EVLA at the American Astronomical Society's meeting in Boston, Massachusetts.
Carilli presented highlights of projects in which researchers from around the world made first use of some of the EVLA's new capabilities while those capabilities still are being tested. The EVLA already is providing new and tantalizing insights on a wide range of objects from our nearby cosmic neighborhood to the far reaches of the distant universe.
- Shedding new light on a critical aspect in the formation of Sun-like stars, EVLA observations, combined with earlier data from NRAO's Green Bank Telescope, revealed previously unseen detail of molecular gas near a very young star. Jaime Pineda, of the European Southern Observatory and the University of Manchester, and his colleagues studied emission of ammonia molecules and found complex structure in a region where the gas cloud's random, turbulent motions have been "smoothed out" to allow the gas to collapse into stars. Their new image shows that gas in a region of "coherent" motion can fragment into filaments and its own gravity can cause it to collapse into a new star.
- The improved quality of EVLA images helped show how large ejections of matter from massive young stars can interact with their surroundings and play a key role in the evolution of galaxies. Grazia Umana of the Astrophysical Observatory of Catania, in Italy, led a team studying such a star about 5,500 light-years away that is surrounded by at least two shells of ejected material. The EVLA image showed that the inner shell probably is overtaking the outer shell, creating shockwaves.
- Another team, led by Mark Claussen of the NRAO, used radio waves emitted by cyanoacetylene (HC3N) molecules to map multiple shells of material ejected by an old giant star. Their images trace the mass-ejection history of this star over an 800-year period. This work was made possible by the new frequency coverage of the EVLA and also by its greatly improved capability to analyze the data received.
- A set of new analysis algorithms, combined with the EVLA's sensitivity and high resolution, allowed researchers to separate the emission from supernova remnants from emission from other sources and make the most detailed images ever of one such object. Previous techniques sacrificed sensitivity or resolution, but Sanjay Bhatnagar of the NRAO and his colleagues showed that the EVLA will be able to survey the plane of our Milky Way Galaxy and distinguish the remnants of previously unseen supernova explosions from other objects.
- The greater sensitivity of the EVLA has made it a valuable tool for studying relatively nearby dwarf galaxies that many astronomers think are the type that formed the building blocks for larger galaxies in the early universe. Volker Heesen of the University of Hertfordshire in the United Kingdom and his colleagues studied a dwarf galaxy called IC 10, finding a magnetic "superbubble" in the galaxy.