Daniela Opitz ( University of New South Wales , Australia ) and colleagues used the fine spatial resolution of the Gemini Multi-conjugate adaptive optics System ( GeMS ) and the Gemini South Adaptive Optics Imager ( GSAOI ) to begin to answer these questions , examining a small sample of five Y dwarfs . The delivered Full-Width at Half-Maximum was ~ 0.1arcsecond and the limiting angular separation was around 0.04 arcsecond . Although the observations were sufficiently sensitive to detect companions of roughly equal mass at separations of 0.5 – 1.9 astronomical units ( AU ), they did not find any evidence for binaries . Figure 15 shows the limits on separation and brightness for a binary companion to one of the Y dwarfs studied .
At least one of the sources had previously been identified as “ overluminous .” The presence of clouds in the atmosphere , rather than a companion , may account for the excess luminosity . The few cases observed here are a good start , not a definitive determination of the general trends . They do point to the extreme scenarios ( separations less than 1 AU and extremely faint sources ) that may arise in cases of Y dwarf binaries . This work is featured on the Gemini website , and complete results appear in The Astrophysical Journal .
A Supermassive Black Hole That Wasn ’ t So Massive
One sign of an extreme supermassive black hole at a galaxy ’ s core is a light deficit — the consequence of stars ejected from the central region . The brightest cluster galaxy of Abell 85 had been identified as such an example , claimed to host one of the most massive black holes ever detected in the Universe at around 10 11 M Sun
.
Juan Madrid , then a Science Fellow at Gemini South , along with Carlos Donzelli ( Observatorio Astronómico de Córdoba , Argentina ), used images obtained with the Gemini Multi-Object Spectrograph ( GMOS ) on Gemini South ( Figure 16 ) to probe the galaxy ’ s center and demonstrate that the black hole ’ s mass is not so extreme . Rather than a deficit , data from their Director ’ s Discretionary Time program show the strong nuclear emission in the central kiloparsec as a light excess that may be due to a nuclear stellar disk . The observations were very short , only seven minutes . The key to the measurement was the spatial resolution to probe the innermost arcsecond . More information about this work is posted at the Gemini website , and full results are published in The Astrophysical Journal .
The Fastest Quasar Ultraviolet Wind
Quasar winds may be fundamental to the growth of black holes and the evolution of galaxies , being an intimate part of the feedback mechanism that regulates black holes and stellar growth over cosmic time . Jesse Rogerson ( York University , Canada ) and collaborators have discovered an extreme example , the fastest ultraviolet wind , whose velocity approaches 20 % of the speed of light .
The researchers originally used the Sloan Digital Sky Survey to find quasars that show new broad absorption line troughs . Further obser-
Figure 16 . GMOS-South image of the center of the Abell 85 galaxy cluster , which shows that the brightest cluster galaxy at the center does not contain the most massive known black hole in the Universe , contrary to previous estimates .
January 2017 | 2016 Year in Review GeminiFocus
29