3 min read

A Lot of Galaxies Need Guarding in this NASA Hubble View

Much like the eclectic group of space rebels in the upcoming film Guardians of the Galaxy Vol. 2, NASA’s Hubble Space Telescope has some amazing superpowers, specifically when it comes to observing innumerable galaxies flung across time and space.

A stunning example is a galaxy cluster called Abell 370 that contains an astounding assortment of several hundred galaxies tied together by the mutual pull of gravity. That’s a lot of galaxies to be guarding, and just in this one cluster!

a packed field of galaxies and curved blue streaks
Galaxy cluster Abell 370 contains several hundred galaxies tied together by the mutual pull of gravity. Photographed in a combination of visible and near-infrared light, the brightest and largest galaxies are the yellow-white, massive, elliptical galaxies containing many hundreds of billions of stars each. Spiral galaxies have younger populations of stars and are bluish. Mysterious-looking arcs of blue light are distorted images of remote galaxies behind the cluster. The cluster acts as a huge lens in space that magnifies and stretches images of background galaxies like a funhouse mirror.
NASA, ESA, and J. Lotz and the HFF Team (STScI)

Photographed in a combination of visible and near-infrared light, the immense cluster is a rich mix of a variety of galaxy shapes. The brightest and largest galaxies in the cluster are the yellow-white, massive, elliptical galaxies containing many hundreds of billions of stars each. Spiral galaxies — like our Milky Way — have younger populations of stars and are bluish.

Entangled among the galaxies are mysterious-looking arcs of blue light. These are actually distorted images of remote galaxies behind the cluster. These far-flung galaxies are too faint for Hubble to see directly. Instead, the cluster acts as a huge lens in space that magnifies and stretches images of background galaxies like a funhouse mirror. The massive gravitational field of the foreground cluster produces this phenomenon. The collective gravity of all the stars and other matter trapped inside the cluster warps space and affects light traveling through the cluster, toward Earth.

The Hubble Space Telescope is keeping watch over many, many galaxies using the combined superpowers of its incredible optics and a quirk of nature called gravitational lensing. - Download video in HD formats from NASA Goddard's Scientific Visualization Studio.
NASA's Goddard Space Flight Center/Katrina Jackson

Nearly a hundred distant galaxies have multiple images caused by the lensing effect. The most stunning example is “the Dragon,” an extended feature that is probably several duplicated images of a single background spiral galaxy stretched along an arc.

12 frames of galaxy clusters
This is a gallery of the Hubble Space Telescope Frontier Fields. The top six panels are massive galaxy clusters that act as huge lenses in space, magnifying and stretching images of remote galaxies behind each cluster that are too faint for Hubble to see directly. While one of the telescope’s cameras looked at each cluster of galaxies, another camera simultaneously viewed an adjacent patch of sky. This second region is called a "parallel field" — a seemingly sparse portion of sky that provides a deep look into the early universe. Astronomers observed each of the six clusters and six parallel fields in both near-infrared and visible light. This allowed scientists to create more detailed, overlapping, and complete images.
NASA, ESA, STScI, and the HFF team

Astronomers chose Abell 370 as a target for Hubble because its gravitational lensing effects can be used for probing remote galaxies that inhabited the early universe.

Abell 370 is located approximately 4 billion light-years away in the constellation Cetus, the Sea Monster. It is the last of six galaxy clusters imaged in the recently concluded Frontier Fields project. This ambitious, community-developed collaboration among NASA’s Great Observatories and other telescopes harnessed the power of massive galaxy clusters and probed the earliest stages of galaxy development. The program reveals galaxies that are 10 to 100 times fainter than any previously observed.

For more information about Hubble, visit: www.nasa.gov/hubble or http://hubblesite.org/news_release/news/2017-20

Contacts:
Ann Jenkins / Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4488 / 410-338-4514
jenkins@stsci.edu / villard@stsci.edu

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NASA's Goddard Space Flight Center/Jenny Hottle