Hubble discovers the extreme age of the ghostly light between galaxies

Jan. 5 () –

The ghostly haze emitted by countless stars wandering between galaxies like lost souls dates back billions of years, suggest new Hubble observations.

In other words, these stars are not the product of more recent dynamic activity within a cluster of galaxies. which would take them out of normal galaxies.

These stars are not gravitationally bound to any galaxy in the cluster. How did the stars get so spread out in the cluster? There are several theories that point to the possibility that the stars were torn from the cluster galaxies, that they dispersed after the merger of galaxies, or that they were present in the first years of the cluster’s formation, billions of years ago.

A recent infrared survey by the NASA/ESA Hubble Space Telescope, looking for this so-called “intracluster light”, sheds new light on the mystery.

The study included 10 galaxy clusters located at a distance of nearly 10 billion light-years. These measurements must be made from space because the faint intracluster light is 10,000 times dimmer than the night sky seen from the ground. The study reveals that the fraction of intracluster light in relation to the total light of the cluster remains constant over billions of years. This means that these stars were already homeless in the early stages of cluster formation.

Shown here are Hubble Space Telescope images of two massive galaxy clusters named MOO J1014+0038 (left panel) and SPT-CL J2106-5844 (right panel). The artificially added blue color is translated from Hubble data that captured a phenomenon called intracluster light. This extremely faint glow traces a smooth distribution of light from wandering stars scattered throughout the cluster. Billions of years ago, stars broke away from their parent galaxies and are now drifting through intergalactic space.

The near-infrared capability and sensitivity of the NASA/ESA/CSA James Webb Space Telescope will greatly expand the search for intracluster stars in the depths of the Universe and thus help solve the mystery, reports the ESA website dedicated to Hubble.