A team of astronomers is proposing that huge spiral patterns seen around some newborn stars, merely a few million years old (about one percent our sun's age), may be evidence for the presence of giant, unseen planets. This idea not only opens the door to a new method of planet detection, but also could offer a look into the early formative years of planet birth. Though astronomers have cataloged thousands of planets orbiting other stars, the very earliest stages of planet formation are elusive because nascent planets are born and embedded inside vast, pancake-shaped disks of dust and gas encircling newborn stars. The conclusion that planets may betray their presence by modifying circumstellar disks on large scales is based on detailed computer modeling of how gas-and-dust disks evolve around newborn stars.
Abundant molecular oxygen in the coma of comet 67P/Churyumov–Gerasimenko
Nature 526, 7575 (2015). doi:10.1038/nature15707
Authors: A. Bieler, K. Altwegg, H. Balsiger, A. Bar-Nun, J.-J. Berthelier, P. Bochsler, C. Briois, U. Calmonte, M. Combi, J. De Keyser, E. F. van Dishoeck, B. Fiethe, S. A. Fuselier, S. Gasc, T. I. Gombosi, K. C. Hansen, M. Hässig, A. Jäckel, E. Kopp, A. Korth, L. Le Roy, U. Mall, R. Maggiolo, B. Marty, O. Mousis, T. Owen, H. Rème, M. Rubin, T. Sémon, C.-Y. Tzou, J. H. Waite, C. Walsh & P. Wurz
The composition of the neutral gas comas of most comets is dominated by H2O, CO and CO2, typically comprising as much as 95 per cent of the total gas density. In addition, cometary comas have been found to contain a rich array of other molecules, including sulfuric compounds and complex hydrocarbons. Molecular oxygen (O2), however, despite its detection on other icy bodies such as the moons of Jupiter and Saturn, has remained undetected in cometary comas. Here we report in situ measurement of O2 in the coma of comet 67P/Churyumov–Gerasimenko, with local abundances ranging from one per cent to ten per cent relative to H2O and with a mean value of 3.80 ± 0.85 per cent. Our observations indicate that the O2/H2O ratio is isotropic in the coma and does not change systematically with heliocentric distance. This suggests that primordial O2 was incorporated into the nucleus during the comet’s formation, which is unexpected given the low upper limits from remote sensing observations. Current Solar System formation models do not predict conditions that would allow this to occur.
US astronomers stuck in grant-rejection cycle
Nature 526, 7575 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.18631
Author: Chris Cesare
The plummeting success rates in grant applications in the last decade are linked to flat budgets and more resubmitted proposals.
Astronomy: Red-giant rogue in Andromeda
Nature 526, 7575 (2015). doi:10.1038/526612c
Astronomers have spotted a giant 'runaway star' speeding through the Andromeda galaxy; the first of its kind seen outside the Milky Way.Whereas most stars flow together around the centre of their galaxy, some, known as runaways, travel at different directions and speeds to their