NGC 613

A spiral galaxy’s brights and darksNGC 613 is a barred spiral galaxy about 65 million light-years away in the constellation of The Sculptor. It’s core looks bright and uniformly white in this image as a result of the combined light shining from the high concentration of stars packed into the core, but a massive black hole lurks at the center of this brilliance. Its mass is estimated at about 10 times that of the Milky Way’s supermassive black hole, and it is consuming stars, gas, and dust. As matter descends into the black hole’s, it radiates energy, but when looking at the galaxy in the optical and infrared wavelengths used to take this image, there is no trace of its dark heart.

Image Credit: ESA / NASA

The Medusa Merger

The Medusa Merger (aka NGC 4194) is a pair of interacting galaxies in the constellation Ursa Major. As one galaxy has consumed a smaller gas-rich system, throwing out streams of stars and dust into space, which resemble the writhing snakes that Medusa, a monster in Greek mythology famously had on her head in place of hair. Its gas-rich central region, the Eye of Medusa, is an area of extremely intense star formation.

Image Credit: NASA / ESA

Mergers and Acquisitions

NGC 2207 is a pair of colliding spiral galaxies. Although individual stars are too far apart to collide, the material between them combines to create high-density pockets of gas. Those, in turn, gravitationally collapse, triggering a firestorm of star birth. This galaxy collision will go on for several millions of years, leaving the galaxies’ shapes completely altered.

This animation combines data from three satellite observatories. Optical: Hubble data shows trails of stars and gas trace out spiral arms, stretched by the tidal pull between the galaxies. Infrared: Spitzer data reveals the glow of warm dust; raw material for the creation of new stars and planets. X-ray: Chandra view reveals areas of active star formation and the birth of super star clusters.

Video Credit: STScI

Not Quite Dead Yet

The dwarf elliptical galaxy Messier 110 may not look like much, but our near neighbor is an unusual example of its type. M110 is a member of the Local Group, the gathering of galaxies that includes the Milky Way and the galaxies closest to it. Messier 110 is one of the small satellite galaxies circling the Andromeda galaxy, our nearest major galaxy. Elliptical galaxies have smooth and almost featureless structures lacking arms and notable pockets of star formation.

Because they lack stellar nurseries and contain mostly old stars, elliptical galaxies are often considered “dead” when compared to their spiral relatives. However, astronomers have spotted signs of a population of young, blue stars at the center of Messier 110; it may not be “dead” yet.

Image Credit: NASA / ESA

A Dim Galaxy

UGC 695 is located 30 million light-years away within the constellation Cetus. It’s a low-surface-brightness galaxy. LSB galaxies are so faint that their brightness is less than the nighttime background brightness of Earth’s atmosphere, making them nearly impossible to observe. This image was taken by the Hubble Space Telescope. Their low brightness is the result of the relatively small number of stars in them—most of the matter in these galaxies is in huge clouds of gas and dust. Thus, LSB galaxies have a high fraction of dark matter relative to the number of stars they contain.

Image Credit: NASA / ESA

Saturn and Some of Its Moons

The animation shows the orbits of Saturn’s visible moons Tethys, Janus, Mimas, Enceladus, and Rhea over the observing run in June, 2019 (with elapsed time bar).

Video Credits: NASA / ESA / A. Simon (Goddard Space Flight Center) / M.H. Wong (University of California, Berkeley) / J. DePasquale (STScI)