X-ray binary 4U 1907+09: NuSTAR observations reveal flux variability and spin-down

Using NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), Indian astronomers have performed X-ray observations of an X-ray binary designated 4U 1907+09. Results of the observational campaign, published April 3 on the arXiv preprint server, yield new insights into the variability of this source, shedding more light on its nature.