ultra-diffuse

English

Alternative forms

• ultra diffuse

Adjective

ultra-diffuse (comparative more ultra-diffuse, superlative most ultra-diffuse)

1. Extremely diffuse.
2. (astronomy) Specifically, designating a type of galaxy with a very low proportion of visible stars compared to the Milky Way, and hence a very low luminosity.
   • 2016, Van der Burg, Muzzin & Hoekstra, ‘The abundance and spatial distribution of ultra-diffuse galaxies in nearby galaxy clusters’, Astronomy & Astrophysics:

     In the next sections we study the properties of galaxies that satisfy our criteria to be ultra diffuse, and consider the contribution from galaxies in the fore- and background using the CFHTLS fields.

   • 2018 March 28, Rebecca Boyle, Scientific American:

     The galaxy, called NGC1052-DF2, is about 65 million light years away. It is almost as big as the Milky Way but is “ultra-diffuse,” meaning it contains just a vanishing fraction of the stars found in our galaxy—only 1 percent, in this case.

Derived terms

• ultra diffuse galaxy