Supernovae are the most powerful stellar explosions in the universe. Some of them are produced by the detonation of a white dwarf, the stripped-down core of an ordinary star at the end of its life. But 12 years ago, astronomers began noticing weak stellar blasts, a kind of mini-supernova. When one such explosion occurred in the galaxy NGC 1309, astronomers looking through Hubble archival images found for the first time the star system that produced the supernova blast of a white dwarf.
Astronomy: Fresh look at Galactic rim
Nature 512, 7512 (2014). doi:10.1038/512008b
A survey has provided the most detailed look yet at a mysterious ring of stars at the fringes of the Milky Way.Using data from the Pan-STARRS1 telescope in Hawaii, Colin Slater and Eric Bell at the University of Michigan in Ann Arbor and their
Astrophysics: Best gauge of exoplanet size
Nature 512, 7512 (2014). doi:10.1038/512009b
Astronomers have made the most precise measurement so far of an exoplanet's size — for Kepler-93b, which orbits a star around 100 parsecs away.Sarah Ballard at the University of Washington in Seattle and her colleagues estimated the planet's diameter at about 18,800 kilometres (1.48
Astrophysics: Novae join the γ-ray generators
Nature 512, 7512 (2014). doi:10.1038/512009c
Astronomers have identified a previously unknown source of cosmic γ-radiation.High-energy γ-rays are released in extremely energetic events such as pulsars and supernovae. But they were thought to be unlikely products of classical novae: explosions that occur on the surfaces of compact, burnt-out stars called
Astrophysics: Portrait of a doomed star
Nature 512, 7512 (2014). doi:10.1038/512034a
Authors: Stephen Justham
Some stars explode in thermonuclear supernovae, but understanding of why this occurs comes mainly from indirect clues. Now, the progenitor of a member of a strange class of such explosions may have been detected directly. See Letterp.54
A luminous, blue progenitor system for the type Iax supernova 2012Z
Nature 512, 7512 (2014). doi:10.1038/nature13615
Authors: Curtis McCully, Saurabh W. Jha, Ryan J. Foley, Lars Bildsten, Wen-fai Fong, Robert P. Kirshner, G. H. Marion, Adam G. Riess & Maximilian D. Stritzinger
Type Iax supernovae are stellar explosions that are spectroscopically similar to some type Ia supernovae at the time of maximum light emission, except with lower ejecta velocities. They are also distinguished by lower luminosities. At late times, their spectroscopic properties diverge from those of other supernovae, but their composition (dominated by iron-group and intermediate-mass elements) suggests a physical connection to normal type Ia supernovae. Supernovae of type Iax are not rare; they occur at a rate between 5 and 30 per cent of the normal type Ia rate. The leading models for type Iax supernovae are thermonuclear explosions of accreting carbon–oxygen white dwarfs that do not completely unbind the star, implying that they are ‘less successful’ versions of normal type Ia supernovae, where complete stellar disruption is observed. Here we report the detection of the luminous, blue progenitor system of the type Iax SN 2012Z in deep pre-explosion imaging. The progenitor system's luminosity, colours, environment and similarity to the progenitor of the Galactic helium nova V445 Puppis suggest that SN 2012Z was the explosion of a white dwarf accreting material from a helium-star companion. Observations over the next few years, after SN 2012Z has faded, will either confirm this hypothesis or perhaps show that this supernova was actually the explosive death of a massive star.
Binary star to spill celestial secrets
Nature 512, 7512 (2014). http://www.nature.com/doifinder/10.1038/512013a
Author: Alexandra Witze
Close approach and violent interaction of stars in η Carinae system will provide rare insight into stellar enigma.