Credit: NASA, ESA, Z. Shen and P. van Dokkum (Yale University), and S. Danieli (Institute for Advanced Study)

This Hubble Space Telescope snapshot reveals an unusual galaxy that

researchers call a “see-through galaxy.” The giant cosmic cotton

ball is so diffuse and its ancient stars are so spread out that

distant galaxies in the background can be seen through it.

Called an ultra-diffuse galaxy, this oddball is almost as wide

as the Milky Way, but it contains only 1/200th the number of stars

as our galaxy. The ghostly galaxy doesn’t appear to have a

noticeable central region, or even spiral arms and a disk.

Researchers calculated a more accurate distance to the galaxy,

named NGC 1052-DF2, or DF2, by using Hubble to observe about

5,400 aging red giant stars. Red giant stars all reach the same

peak brightness, so they are reliable yardsticks to measure

distances to galaxies.

The research team estimates that DF2 is 72 million light-years from

Earth. They say this distance measurement solidifies their claim

that DF2 lacks dark matter, the invisible glue that makes up the

bulk of the universe’s contents. The galaxy contains at most 1/400th

the amount of dark matter that the astronomers had expected.

The observations were taken between December 2020 and March 2021 with

Hubble’s Advanced Camera for Surveys.

Provider: Space Telescope Science Institute

Image Source: https://hubblesite.org/contents/news-releases/2021/news-2021-025

Curator: STScI, Baltimore, MD, USA

Image Use Policy: http://hubblesite.org/copyright/