Hubble's picture of the week is a galaxy with a tail 100,000 light-years long
Galaxy NGC 2775 is located 67 million light-years away in the constellation Cancer (The Crab). From Hubble’s face-on view of this galaxy, it has a smooth, seemingly clear center. This gives it the appearance of an elliptical galaxy.
But it also has a ring of dust with patchy star clusters, making it look like a spiral galaxy. This complicated appearance has left scientists divided. Some have called NGC 2775 a lenticular galaxy. That is, a galaxy with the features of both spiral and elliptical galaxies.
It would be fascinating to know how this galaxy and its complex shape came to be. For lenticular galaxies, one of the theories that exists is that these galaxies were formed when spiral galaxies merged with other galaxies.
Interestingly, there is some evidence that NGC 2775 could have formed in this way. Past studies have shown that NGC 2775 has a tail of hydrogen gas that stretches almost 100,000 light-years around the galaxy. This tail could be a remnant of one or more galaxies that merged with NGC 2775.
Hubble previously viewed NGC 2775 in 2020. But this new image offers more data. It includes observations made in H-alpha light.
H-alpha is a wavelength of red light that makes tracing star-forming regions possible. Young massive stars emit intense UV radiation. This radiation ionizes the surrounding hydrogen gas, releasing H-alpha emissions.
This Hubble image shows NGC 2775’s bright, glowing core located in the clear center. Immediately around that center is an inner ring of dust. The galaxy has a thicker outer ring of dust around its edge. In between the inner and outer rings is a swirling web of dust strands. Young blue stars and red nebulae can be seen behind the dust.
