Celebrating 170th anniversary of the discovery of Neptune, I review the story of the discovery that startled the world. The story is an interplay of scientific triumph and human weakness and an example of how science works in a socio-political context.
Astrobiology: Martian dance of fiction and fact
Nature 538, 7625 (2016). doi:10.1038/538317e
Author: Jonathan Cowie
In marking the H. G. Wells anniversary, you highlight what Carl Sagan dubbed the “dance” between science fiction and science fact (see www.nature.com/scifispecial).Wells's The War of the Worlds saw the Martian invasion stopped in its tracks by Earth pathogens (S. J.
Ultraluminous X-ray bursts in two ultracompact companions to nearby elliptical galaxies
Nature 538, 7625 (2016). doi:10.1038/nature19822
Authors: Jimmy A. Irwin, W. Peter Maksym, Gregory R. Sivakoff, Aaron J. Romanowsky, Dacheng Lin, Tyler Speegle, Ian Prado, David Mildebrath, Jay Strader, Jifeng Liu & Jon M. Miller
A flaring X-ray source was found near the galaxy NGC 4697 (ref. 1). Two brief flares were seen, separated by four years. During each flare, the flux increased by a factor of 90 on a timescale of about one minute. There is no associated optical source at the position of the flares, but if the source was at the distance of NGC 4697, then the luminosities of the flares were greater than 1039 erg per second. Here we report the results of a search of archival X-ray data for 70 nearby galaxies looking for similar flares. We found two ultraluminous flaring sources in globular clusters or ultracompact dwarf companions of parent elliptical galaxies. One source flared once to a peak luminosity of 9 × 1040 erg per second; the other flared five times to 1040 erg per second. The rise times of all of the flares were less than one minute, and the flares then decayed over about an hour. When not flaring, the sources appear to be normal accreting neutron-star or black-hole X-ray binaries, but they are located in old stellar populations, unlike the magnetars, anomalous X-ray pulsars or soft γ repeaters that have repetitive flares of similar luminosities.
Astrophysics: Unexpected X-ray flares
Nature 538, 7625 (2016). doi:10.1038/538321a
Authors: Sergio Campana
Two sources of highly energetic flares have been discovered in archival X-ray data of 70 nearby galaxies. These flares have an undetermined origin and might represent previously unknown astrophysical phenomena. See Letter p.356
Astronomy: Two stars have three disks
Nature 538, 7625 (2016). doi:10.1038/538292b
Young stars are surrounded by a rotating disk of gas and dust, from which planets are born — but astronomers have discovered that one pair of young stars orbiting around each other has three disks, not just two.Christian Brinch at the University of Copenhagen