A research team of the Department of Physics, Keio
University, has discovered a molecular cloud with a peculiar helical structure
by observation with the NRO 45m Telescope at Nobeyama Radio Observatory (NAOJ),
National Astronomical Observatory of Japan. The team led by Shinji Matsumura, a
second year Ph. D. candidate, and Tomoharu Oka, an Associate Professor, named
it a "pigtail" molecular cloud from its morphology. The “pigtail”
molecular cloud is located in the Galactic center, approximately 30,000 light
years away from the solar system. Giant molecular clouds in this region are
orbit around the Galactic center along two closed orbits. At the bottom of the
pigtail molecular cloud, these two orbits intersect.