GeminiFocus 2015 Year in Review | Page 73

The observations of the tightly packed cluster used Gemini Observatory’s powerful adaptive optics system at the Gemini South telescope in Chile. A technical jewel named GeMS (derived from “Gemini Multi-conjugate adaptive optics System”), in combination with the powerful infrared camera Gemini South Adaptive Optics Imager (GSAOI), was able to penetrate the dense fog surrounding Liller 1 and to provide astronomers with this unprecedented view of its stars. This has been made possible thanks to the combination of two specific characteristics of GeMS: first, the capability of operating at near-infrared wavelengths (especially in the K pass-band); second, an innovative and revolutionary way to remove the distortions (blurriness) that the Earth’s turbulent atmosphere inflicts on astronomical images. To compensate for the degrading effects of the Earth’s atmosphere, the GeMS system uses three natural guide stars, a constellation of five laser guide stars, and multiple deformable mirrors. The correction is so fine that astronomers are provided with images of unparalleled sharpness. In the best K-band exposures of Liller 1, stellar images have an angular resolution of only 75 milliarcseconds, just slightly larger than the theoretical limit (known as the diffraction limit) of Gemini’s 8-meter mirror. This means that GeMS almost perfectly corrected Earth’s atmospheric distortions. The international research team published the results in the June 15th issue of The Astrophysical Journal (volume 806, page 152). The astro-ph version of the article can be found here. The results achieved on Liller 1 have been so important that the research team is currently expanding their work to other globular clusters, which promise to deliver even more exciting science. January 2016 Background: Stellar Collisions Stellar collisions are important because they can provide the key to understanding how certain exotic objects, which cannot be explained by the passive evolution of single stars, originate. “Blue Stragglers,“ for instance, are old stars that mysteriously appear younger than they should be; these exotic stars may be formed by nearly headon collisions that cause the stars to merge, mixing their nuclear fuel and restoking the fire of nuclear fusion. But collisions can also involve binary systems, with the effect of shrinking the ini F