Vol. 634
6. Interstellar and circumstellar matter

The HI/OH/recombination line survey of the inner Milky Way (THOR): data release 2 and H I overview

The Data Release 2 of The HI/OH/recombination line survey of the Milky Way (THOR) provides the most detailed view so far of the first Galactic quadrant at a 21 cm wavelength. The authors have combined observations from the Karl G. Jansky Very Large Array (VLA) and Green Bank Telescope (GBT) to recover the large-scale structure of the HI emission and achieve an angular resolution of 40". Among their results, the authors derive an opacity-correction factor that implies a total atomic gas mass of 9.4–10.5x10^9 M_sun when applied to the entire Milky Way.