New observations of the giant elliptical galaxy, Messier 87, have revealed that it has swallowed an entire medium-sized galaxy over the last billion years. For the first time a team of astronomers at the Max Planck Institute for Extraterrestrial Physics and other institutes has been able to track the motions of 300 glowing planetary nebulae to find clear evidence of this event. In addition, they found evidence of excess light coming from the remains of the totally disrupted victim.
Longobardi A., Arnaboldi M., Gerhard O., Mihos J. C., 2015a, A&A, 579, L3
The Milky Way’s bar is longer, thinner, and ends closer to the Sun than previously thought. Combining several large stellar surveys, scientists at the Max Planck Institute for Extraterrestrial Physics have now mapped the complete inner region of our Galaxy, containing the majority of its stars. Because the bar is also oriented more towards the Sun, it ends much closer to us, and therefore has a greater influence on the motion of stars near the Sun.
The Milky Way’s bar also gets thinner away from the centre of the galaxy. Near the end of the bar it becomes so thin that the scientists have termed the bar super-thin, and believe that the thinness of this new component is probably related to younger stars that were born with low velocities about one billion years ago.
Christopher Wegg, Ortwin Gerhard and Matthieu Portail, 2015, MNRAS, 450, 4050