The top panel shows the original stellar velocity data, as collected using the DEIMOS spectrograph at the W.M. Keck Observatory. The bottom panel shows a numerical model that matches the data remarkably well. Credit: M. Cappellari and the SLUGGS team
Example of mapping out and analyzing the speeds of stars in an elliptical galaxy. Blue colors show regions where the stars are hurtling toward the observer on Earth, and red colors show regions that are moving away, in an overall pattern of coherent rotation. The top panel shows the original data, as collected using the DEIMOS spectrograph at the W.M. Keck Observatory. The bottom panel shows a numerical model that matches the data remarkably well, from using the combined gravitational influence of luminous and dark matter. Credit: M. Cappellari and the SLUGGS team