Crunch time for Canada’s role in mega-telescope
Nature 519, 7543 (2015). http://www.nature.com/doifinder/10.1038/519270a
Author: Alexandra Witze
Astronomers ask federal government to honour promise for Thirty Meter Telescope.
Highly efficient star formation in NGC 5253 possibly from stream-fed accretion
Nature 519, 7543 (2015). doi:10.1038/nature14218
Authors: J. L. Turner, S. C. Beck, D. J. Benford, S. M. Consiglio, P. T. P. Ho, A. Kovács, D. S. Meier & J.-H. Zhao
Gas clouds in present-day galaxies are inefficient at forming stars. Low star-formation efficiency is a critical parameter in galaxy evolution: it is why stars are still forming nearly 14 billion years after the Big Bang and why star clusters generally do not survive their births, instead dispersing to form galactic disks or bulges. Yet the existence of ancient massive bound star clusters (globular clusters) in the Milky Way suggests that efficiencies were higher when they formed ten billion years ago. A local dwarf galaxy, NGC 5253, has a young star cluster that provides an example of highly efficient star formation. Here we report the detection of the J = 3→2 rotational transition of CO at the location of the massive cluster. The gas cloud is hot, dense, quiescent and extremely dusty. Its gas-to-dust ratio is lower than the Galactic value, which we attribute to dust enrichment by the embedded star cluster. Its star-formation efficiency exceeds 50 per cent, tenfold that of clouds in the Milky Way. We suggest that high efficiency results from the force-feeding of star formation by a streamer of gas falling into the galaxy.
Astronomy: Milky Way has corrugated rings
Nature 519, 7543 (2015). doi:10.1038/519265c
The Milky Way's stars sprawl outwards in a series of concentric ripples, hinting that it might extend farther into space than was thought.Data from the Sloan Digital Sky Survey confirm a previously known ring of stars at about 9,000 parsecs from the Sun. They
Astronomers at the Space Telescope Science Institute and the Johns Hopkins University, both in Baltimore, Maryland, have created a new master catalog of astronomical objects called the Hubble Source Catalog. The catalog provides one-stop shopping for measurements of objects observed with NASA's Hubble Space Telescope.
Nearly 500 million miles from the Sun lies a moon orbiting Jupiter that is slightly larger than the planet Mercury and may contain more water than all of Earth's oceans. Temperatures are so cold, though, that water on the surface freezes as hard as rock and the ocean lies roughly 100 miles below the crust. Nevertheless, where there is water there could be life as we know it. Identifying liquid water on other worlds big or small is crucial in the search for habitable planets beyond Earth. Though the presence of an ocean on Ganymede has been long predicted based on theoretical models, NASA's Hubble Space Telescope found the best evidence for it. Hubble was used to watch aurorae glowing above the moon's icy surface. The aurorae are tied to the moon's magnetic field, which descends right down to the core of Ganymede. A saline ocean would influence the dynamics of the magnetic field as it interacts with Jupiter's own immense magnetic field, which engulfs Ganymede. Because telescopes can't look inside planets or moons, tracing the magnetic field through aurorae is a unique way to probe the interior of another world.