Hubble Captures Puzzling Galaxy
The latest stunning image captured by the NASA/ESA Hubble Space Telescope showcases the enigmatic galaxy NGC 2775, located 67 million light-years away in the constellation Cancer. This galaxy presents a fascinating challenge for astronomers, as it defies easy classification. NGC 2775 features a smooth, featureless center that resembles an elliptical galaxy, yet it also boasts a dusty ring adorned with patchy star clusters, reminiscent of a spiral galaxy. This unique combination raises an intriguing question: is NGC 2775 a spiral, an elliptical, or something entirely different?
The classification of NGC 2775 is further complicated by the fact that we can only observe it from one angle. Some researchers lean towards categorizing it as a spiral galaxy due to its feathery ring of stars and dust, while others suggest it fits the profile of a lenticular galaxy, which embodies characteristics of both spiral and elliptical galaxies. The origins of lenticular galaxies are still a subject of debate among astronomers; they may form from the merging of spiral galaxies or from spiral galaxies that have exhausted their star-forming gas, leading to the loss of their distinctive spiral arms. Alternatively, they could evolve from elliptical galaxies that have accumulated gas into a surrounding disk.
Adding to the intrigue, evidence suggests that NGC 2775 has a history of galactic mergers. Hidden from view in the Hubble image, the galaxy possesses a tail of hydrogen gas that extends nearly 100,000 light-years into space. This faint tail may be the remnants of one or more galaxies that ventured too close to NGC 2775, ultimately being stretched apart and absorbed. This past interaction could explain the galaxy’s peculiar appearance today. Most astronomers currently classify NGC 2775 as a flocculent spiral galaxy, characterized by poorly defined, discontinuous arms that appear as “feathery” tufts of stars. The new Hubble image, enhanced with observations of specific wavelengths of red light emitted by surrounding hydrogen gas, reveals bright, pinkish clumps that indicate regions of active star formation. This advancement in imaging allows astronomers to pinpoint where new stars are being born within this captivating galaxy, further unraveling the mysteries of NGC 2775.
This NASA/ESA Hubble Space Telescope image features a galaxy, NGC 2775, that’s hard to categorize.
ESA/Hubble & NASA, F. Belfiore, J. Lee and the PHANGS-HST Team
This NASA/ESAÂ
Hubble Space Telescope
 image features a galaxy that’s hard to categorize. The galaxy in question is NGC 2775, which lies 67 million light-years away in the constellation Cancer (the Crab). NGC 2775 sports a smooth, featureless center that is devoid of gas, resembling an elliptical galaxy. It also has a dusty ring with patchy star clusters, like a spiral galaxy. Which is it: spiral or elliptical — or neither?
Because we can only view NGC 2775 from one angle, it’s difficult to say for sure. Some researchers classify NGC 2775 as a spiral galaxy because of its feathery ring of stars and dust, while others classify it as a lenticular galaxy. Lenticular galaxies have features common to both spiral and elliptical galaxies.
Astronomers aren’t certain of exactly how lenticular galaxies come to be, and they might form in a variety of ways. Lenticular galaxies might be spiral galaxies that merged with other galaxies, or that have mostly run out of star-forming gas and lost their prominent spiral arms. They also might have started out more like elliptical galaxies, then collected gas into a disk around them.
Some evidence suggests that NGC 2775 merged with other galaxies in the past. Invisible in this Hubble image, NGC 2775 has a tail of hydrogen gas that stretches almost 100,000 light-years around the galaxy. This faint tail could be the remnant of one or more galaxies that wandered too close to NGC 2775 before being stretched apart and absorbed. If NGC 2775 merged with other galaxies in the past, it could explain the galaxy’s strange appearance today.
Most astronomers classify NGC 2775 as a flocculent spiral galaxy. Flocculent spirals have poorly defined, discontinuous arms that are often described as “feathery” or as “tufts” of stars that loosely form spiral arms.
Hubble previously released an image of NGC 2775 inÂ
2020
. This new version adds observations of a specific wavelength of red light emitted by clouds of hydrogen gas surrounding massive young stars, visible as bright, pinkish clumps in the image. This additional wavelength of light helps astronomers better define where new stars are forming in the galaxy.
