The recent discovery of a third galaxy with minimal dark matter, all three aligned on a straight line, has astronomers intrigued. This phenomenon challenges our understanding of galaxy formation and the role of dark matter. The galaxy, NGC 1052-DF9, was studied using the W. M. Keck Observatory, revealing its stars move slower than expected, suggesting a lack of a dark matter halo. This finding adds to the mystery of two other similar galaxies, DF2 and DF4, all part of a narrow line of galaxies in the NGC 1052 field. The straight line itself is a crucial clue, hinting at a violent collision between gas-rich galaxies in the past. This collision theory is supported by simulations, but other explanations, such as tidal dwarfs, are also considered. The discovery highlights the importance of dark matter in galaxy formation, and the search for gas along the trail could provide 'smoking gun' evidence to support this theory. However, the measurement is delicate and subject to uncertainties, making it a complex puzzle that requires further investigation.
