ESO astronomers present building block of Milky Way's bulge

According to astronomers with the European Southern Observatory (ESO), a misfit crowd of stars may be some of the original builders of our Milky Way's central bulge.

Francesco Ferraro from the University of Bologna leads a team of astronomers that is focusing infrared eyes on a weird bunch of stars within the globular cluster Terzan 5 in our Milky Way's dusty central bulge. His team theorizes that this odd star grouping is the remnant of a proto-galaxy that merged with the primordial Milky Way billions of years ago. The team's observations have revealed that, unlike the other star clusters found in the bulge, Terzan 5's stars were all born at different times. The stars in Terzan 5 formed during at least two epochs, around 12 billion and 6 billion years ago, the team concluded. Team member Emanuele Dalessandro explains, that Omega Centauri, in the Milky Way's halo, is the only other globular cluster discovered, thus far, that shows as much of the complex composition and history of star formation. ESO's Very Large Telescope (VLT) was able to zoom in on Terzan 5 and produce detailed infrared images, even within this dust enshrouded and most difficult to observe area of the galaxy, using a new technology known as the Multi-conjugate Adaptive Optics Demonstrator (MAD). Adaptive optics instruments like MAD offset some of the effects of atmospheric turbulence that blur astronomical images obtained from ground based telescopes such as the VLT. Ferraro hopes that future observations by his team will unveil several similar systems hidden within the Milky Way's gas-clouded center, and eventually reveal much more about the still hotly debated origin of galaxy bulges. F. R. Ferraro et al. have presented their research (PDF) in a paper published in the 26 November 2009 issue of Nature, “The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge.”