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
Johannes Kepler (1571-1630) is one of the world’s most famous astronomers. He defended Copernicus’s sun-centred universe and discovered that planets move in ellipses. A planet, NASA mission and planet-hunting spacecraft are named after him.
Yet in recent years Kepler and his family have appeared as dubious, even murderous people. In 2004 for example, a team of American journalists alleged that Kepler systematically poisoned the man he succeeded at the court of Rudolf II in Prague: Tycho Brahe. He may well be the scientist with the worst reputation.
But the majority of slurs concern the astronomer’s mother, Katharina. Arthur Koestler’s famous history of astronomy, The Sleepwalkers, where Katharina features as a “hideous little woman” whose evil tongue and “suspect background” predestined her as victim of the witchcraze.
Then there’s John Banville’s prize-winning historical novel Kepler, which vividly portrays Katharina as a crude old woman who makes a dangerous business of healing by boiling potions in a black pot. She meets with old hags in a kitchen infested with cat smells. Outside in her garden lies a dead rat. Kepler desperately tries to hide his mother’s magical arts from his wife as they visit and Katharina searches for a bag filled with bat-wings. This horrendous mother is scary, disgusting, and probably a witch.
There is something behind these hints: the portrayals stem to the astonishing fact that 400 years ago, when her son was at the very height of his scientific career, Katharina Kepler was accused of witchcraft. It is because of this that it has become commonplace in Anglo-American writing to depict Kepler’s mother as a difficult, bizarre and half-crazed old crone.
But what is the real story? Kepler certainly must rank as one of the most influential scientists to come from a disadvantaged background. Whereas Galileo’s father was a noted scholar of music, Kepler’s was a soldier who kept running away from the family. His parents argued and the only brother close to him in age suffered from epilepsy. This made it difficult for the brother to attend school or learn a trade.
Johannes Kepler, by contrast, soon emerged as an extremely talented boy. He was picked up by one of the most advanced Lutheran scholarship systems in Germany at the time and lived in boarding schools. He once fought against a boy who insulted his father, and was in his teens when the father disappeared for good.
Kepler’s model of the solar system.
Kepler wrote bleak little characterisations of his parents and paternal family around the time that he finished university. He also wrote about himself as a flawed young man, obsessively interested in fame, worried about money, unable to communicate his ideas in a straightforward way. These pieces of writing have principally served as evidence who want to depict Kepler and his family as horrendous, even murderous.
Yet these writings need to be put into context. Kepler wrote them very early in his life, and he did so in order to analyse his horoscopes. The whole convention of astrology was to point to character problems, rather than to laud lovely people. Kepler was a deeply Christian man, and one of his most impressive characteristics is how optimistic he soon began to feel about the world he lived in, against his odds and despite looming war. He built his own family and deeply cared about his wife and children. Kepler was confident about the importance of his discoveries and productive, even though he was never offered a university position.
Statue of Katharina Kepler in Eltingen. Harke, CC BY-SA
Then came the accusation against his mother. The proceedings which led to a criminal trial lasted six years. The Imperial mathematician formally took over his mother’s legal defence. No other public intellectual figure would have ever involved themselves in a similar role, but Kepler put his whole existence on hold, stored up his books, papers and instruments in boxes, moved his family to southern Germany and spent nearly a year trying to get his mother out of prison.
Local records for the small town in which Katharina Kepler lived are abundant. There is no evidence that she was brought up by an aunt who was burnt for witchcraft – this was one of the charges which her enemies invented. There is no evidence either that she made a living from healing – she simply mixed herbal drinks for herself and sometimes offered her help to others, like anyone else. A woman in her late 70s, Katharina Kepler withstood a trial and final imprisonment, during which she was chained to the floor for more than a year.
Kepler’s defence was a rhetorical masterpiece. He was able to dismantle the inconsistencies in the prosecution case, and show that the “magical” illnesses for which they blamed his mother could be explained using medical knowledge and common sense. In the autumn of 1621, Katharina was finally set free.
Johannes Kepler and his mother lived through one of the most epic tragedies in the age of the witch-craze. It’s high time to re-evaluate what kind of man Kepler was: he does not deserve to be the scientist with the worst reputation. And nor does his mother deserve to be portrayed as a witch.
The Astronomer And The Witch by Ulinka Rublack is published by Oxford University Press on October 22.
Ulinka Rublack, Professor of Early Modern European History, University of Cambridge.
Ulinka Rublack will be giving a talk at the Cambridge Festival of Ideas on Wednesday 28th October.
The opinions expressed in this article are those of the individual author(s) and do not represent the views of the University of Cambridge.
Ulinka Rublack, Professor of Early Modern European History, discusses the reputation of astronomer Johannes Kepler and his mother Katharina, and the criminal trial for witchcraft that lasted six years.Great Comet of 1577, which Kepler witnessed as a child.
The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.
A disintegrating minor planet transiting a white dwarf
Nature 526, 7574 (2015). doi:10.1038/nature15527
Authors: Andrew Vanderburg, John Asher Johnson, Saul Rappaport, Allyson Bieryla, Jonathan Irwin, John Arban Lewis, David Kipping, Warren R. Brown, Patrick Dufour, David R. Ciardi, Ruth Angus, Laura Schaefer, David W. Latham, David Charbonneau, Charles Beichman, Jason Eastman, Nate McCrady, Robert A. Wittenmyer & Jason T. Wright
Most stars become white dwarfs after they have exhausted their nuclear fuel (the Sun will be one such). Between one-quarter and one-half of white dwarfs have elements heavier than helium in their atmospheres, even though these elements ought to sink rapidly into the stellar interiors (unless they are occasionally replenished). The abundance ratios of heavy elements in the atmospheres of white dwarfs are similar to the ratios in rocky bodies in the Solar System. This fact, together with the existence of warm, dusty debris disks surrounding about four per cent of white dwarfs, suggests that rocky debris from the planetary systems of white-dwarf progenitors occasionally pollutes the atmospheres of the stars. The total accreted mass of this debris is sometimes comparable to the mass of large asteroids in the Solar System. However, rocky, disintegrating bodies around a white dwarf have not yet been observed. Here we report observations of a white dwarf—WD 1145+017—being transited by at least one, and probably several, disintegrating planetesimals, with periods ranging from 4.5 hours to 4.9 hours. The strongest transit signals occur every 4.5 hours and exhibit varying depths (blocking up to 40 per cent of the star’s brightness) and asymmetric profiles, indicative of a small object with a cometary tail of dusty effluent material. The star has a dusty debris disk, and the star’s spectrum shows prominent lines from heavy elements such as magnesium, aluminium, silicon, calcium, iron, and nickel. This system provides further evidence that the pollution of white dwarfs by heavy elements might originate from disrupted rocky bodies such as asteroids and minor planets.
Flows of X-ray gas reveal the disruption of a star by a massive black hole
Nature 526, 7574 (2015). doi:10.1038/nature15708
Authors: Jon M. Miller, Jelle S. Kaastra, M. Coleman Miller, Mark T. Reynolds, Gregory Brown, S. Bradley Cenko, Jeremy J. Drake, Suvi Gezari, James Guillochon, Kayhan Gultekin, Jimmy Irwin, Andrew Levan, Dipankar Maitra, W. Peter Maksym, Richard Mushotzky, Paul O’Brien, Frits Paerels, Jelle de Plaa, Enrico Ramirez-Ruiz, Tod Strohmayer & Nial Tanvir
Tidal forces close to massive black holes can violently disrupt stars that make a close approach. These extreme events are discovered via bright X-ray and optical/ultraviolet flares in galactic centres. Prior studies based on modelling decaying flux trends have been able to estimate broad properties, such as the mass accretion rate. Here we report the detection of flows of hot, ionized gas in high-resolution X-ray spectra of a nearby tidal disruption event, ASASSN-14li in the galaxy PGC 043234. Variability within the absorption-dominated spectra indicates that the gas is relatively close to the black hole. Narrow linewidths indicate that the gas does not stretch over a large range of radii, giving a low volume filling factor. Modest outflow speeds of a few hundred kilometres per second are observed; these are below the escape speed from the radius set by variability. The gas flow is consistent with a rotating wind from the inner, super-Eddington region of a nascent accretion disk, or with a filament of disrupted stellar gas near to the apocentre of an elliptical orbit. Flows of this sort are predicted by fundamental analytical theory and more recent numerical simulations.