Astronomy undergraduates Michael Sandoval and Richard Vo from San Jose University have stumbled upon two of the most dense galaxies ever discovered. The students found that the unique cosmic objects are comparable to other globular clusters; however, the brightness factor exhibited by these galaxies is hundreds to thousands of times greater.
The first galaxy the students discovered is called M59-UCD3, which is approximately 200 times smaller than the Milky Way but is said to be heavier than other galaxies near Earth by about 10,000 times. The other system found by the students is called the M85-HCC1. Although this has almost the same size as many galaxies, its density is approximately a million times greater compared to other galaxies that can be observed on planet Earth. Both systems are known as ultracompact dwarfs (UCDs), a new classification of galaxies.
Aside from the data available in the Sloan Digital Sky Survey, the researchers also analyzed data from the Subaru Telescope, Hubble Space Telescope, and spectroscopy from the Goodman Spectrograph located on the Southern Astrophysical Research Telescope.
Based on their observations, the researchers found that the galaxies are young and that metallic elements are abundant, resembling the center of the galaxies. The cosmic materials are actually the nuclei residues that come from newly formed galaxies. The host galaxies of the two objects are also said to exhibit significant disturbances.
These findings, published in The Astrophysical Journal Letters, made the astronomers think that UCDs have great and promising features that can help provide more information about the histories of galaxies.
"Ultracompact stellar systems like these are easy to find once you know what to look for. However, they were overlooked for decades because no one imagined such objects existed: they were hiding in plain sight," said Vo. When one UCD was discovered by chance, the researchers were motivated to find out other possible UCDs and set themselves to find more, he added.
The students drew inspiration from the fact that formulating a concept, setting out a plan, conducting research and exerting much effort can lead anyone to a new discovery. The conglomeration of these attributes and the help of national facilities for further spectroscopic investigations are helpful interventions to motivate undergraduates to lead astronomical research, particularly those enrolled in teaching universities where lack of budget and equipment is rampant, said Aaron Romanowsky, faculty mentor and coauthor on the study.
Further research will involve analyzing the movement of the stars in the middle of the M59-UCD3 to search for a huge black hole. More UCDs and further understanding about their diversity and frequency of occurrence are also targeted by the group.
