Nuclear ashes and outflow in the eruptive star Nova Vul 1670
Nature 520, 7547 (2015). doi:10.1038/nature14257
Authors: Tomasz Kamiński, Karl M. Menten, Romuald Tylenda, Marcin Hajduk, Nimesh A. Patel & Alexander Kraus
CK Vulpeculae was observed in outburst in 1670–1672 (ref. 1), but no counterpart was seen until 1982, when a bipolar nebula was found at its location. Historically, CK Vul has been considered to be a nova (Nova Vul 1670), but its similarity to ‘red transients’, which are more luminous than classical novae and thought to be the results of stellar collisions, has re-opened the question of CK Vul’s status. Red transients cool to resemble late M-type stars, surrounded by circumstellar material rich in molecules and dust. No stellar source has been seen in CK Vul, though a radio continuum source was identified at the expansion centre of the nebula. Here we report that CK Vul is surrounded by chemically rich molecular gas in the form of an outflow, as well as dust. The gas has peculiar isotopic ratios, revealing that CK Vul's composition was strongly enhanced by the nuclear ashes of hydrogen burning. The chemical composition cannot be reconciled with a nova or indeed any other known explosion. In addition, the mass of the surrounding gas is too large for a nova, though the conversion from observations of CO to a total mass is uncertain. We conclude that CK Vul is best explained as the remnant of a merger of two stars.
Planetary science: A new recipe for Earth formation
Nature 520, 7547 (2015). doi:10.1038/520299a
Authors: Richard W. Carlson
Experimental results suggest that if Earth initially grew by the accumulation of highly chemically reduced material, its core could contain enough uranium to drive the planet's magnetic field throughout Earth's history. See Letter p.337
Astronomy: Hubble's legacy
Nature 520, 7547 (2015). doi:10.1038/520287a
Author: Mario Livio
Twenty-five years after launch, the wild success of the space telescope argues for a new era of bold exploration in the face of tight budgets, says Mario Livio.
Biography of a space telescope: Voices of Hubble
Nature 520, 7547 (2015). http://www.nature.com/doifinder/10.1038/520282a
Author: Alexandra Witze
As the venerable space telescope turns 25 this month, key scientists and engineers recount the highs and lows of its stellar career.
Astrophysics: Neutrinos from a galaxy far away
Nature 520, 7547 (2015). doi:10.1038/520266b
Two of the most energetic neutrinos detected by a telescope in the Antarctic may have come from the cores of distant galaxies.Neutrinos are stable and can travel far in space, so they could shed light on distant astrophysical and galactic objects. The Antarctic telescope