For the first time ever, astronomers have discovered a rare double nucleus in the nearby galaxy NGC 4490, nicknamed as ‘Cocoon Galaxy’, located 30 million light-years away from Earth. A new paper published in the Astrophysical Journal describes it as a ‘clear double nucleus structure’ with both nuclei similar in mass, size and luminosity.
The discovery came through when Allen Lawrence, a 77-year-old Iowa State University master’s degree holder peered at the interacting galaxy pair of the spiral Cocoon Galaxy and its smaller companion, starburst NGC 4485. Now, this galaxy system is about 20 per cent the size of the Milky Way. Scientists said that it is especially rare for a galaxy so small to feature double nucleus.
— Fraser Cain (@fcain) February 6, 2020
Studying the infrared images sourced from NASA’s Wide-field Infrared Survey Explorer, Lawrence found that the larger galaxy had a double nucleus. While one of them showed in visible wavelengths, the other one was shrouded by dust and could only be seen in infrared and radio wavelength. A report quotes Lawrence saying that he saw the double nucleus about seven years ago. But it is the first time that records from optical telescopes and radio telescope that spotted one nucleus each, are being compared to profile the dual nucleus structure.
Going by the study, both the nuclei are similar in size, mass and luminosity not only amongst themselves but also nuclei in other interacting galaxy pairs. It’s also being noted that the double nucleus even explains the occurrence of the massive hydrogen plume that surrounds the galaxy system. Astronomer and contributing author Curtis Struck explained in a statement how he thinks a double nucleus could have a share in the formation of supermassive black holes found at the heart of some galaxies.
Astronomers think that there are other things that make this study interesting, “The most straightforward interpretation of the observations is that NGC 4490 is itself a late-stage merger remnant” of a tad earlier collision of two galaxies, the authors wrote.