Mergers and Acquisitions

An interacting colossusThis picture shows a galaxy known as NGC 6872 in the constellation of Pavo (The Peacock). Its unusual shape is caused by its interactions with the smaller galaxy called IC 4970 that can be seen just above it. The pair are roughly 300 million light-years away from Earth.

NGC 6872 measures over 500,000 light-years across. It’s the second largest spiral galaxy discovered thus far. Our own galaxy, the Milky Way, measures around 100,000 light-years across.

The upper left spiral arm of NGC 6872 appears distorted and is filled with star-forming regions which appear blue on this Hubble image. That may have been be caused by IC 4970 recently (only about 130 million years ago) passing through this spiral arm. Astronomers have noted that NGC 6872 seems to be relatively sparse in terms of free hydrogen, which is the basis material for new stars. It is probable that if it weren’t for its interactions with IC 4970, NGC 6872 might not have been able to produce these new bursts of star formation.

Image Credit: NASA / ESA

Rubin’s Galaxy

Rubin’s Galaxy (aka UGC 2885) is a giant spiral galaxy about 232 million light-years away. It’s about 800,000 light-years across—roughly 8 times the diameter of the Milky Way. Astronomers estimate it contain a trillion stars, 10 times as many as the Milky Way.

Image Credit: NASA / ESA / B. Holwerda (University of Louisville)

Butterfly Nebula

m2d9_hubble_985What happens when a star dies? In the case of low-mass stars like our Sun and M2-9 pictured above, such stars transform themselves into white dwarfs by throwing off their outer gaseous envelopes. The expelled gas often forms a planetary nebula that fades away over thousand of years. M2-9 is a butterfly planetary nebula 2100 light-years away. There are two stars orbiting inside the central gaseous disk 10 times larger than the orbit of Pluto. The expelled gas of the dying star breaks out from the disk in a bipolar pattern.

Image Credit: NASA / ESA

The Case of the Reappearing Supernova

This animation demonstrates how light from Supernova Requiem was split into multiple images by a massive foreground cluster of galaxies along its 10 billion light-year path to Earth. The cluster’s gravity warps the fabric of space which magnified, brightened, and split the supernova’s light into multiple mages detected in 2016 by the Hubble Space Telescope.

However, some of the exploded star’s light is taking a longer path to Earth. It passed through the cluster’s central region where gravity is the strongest. The combination of gravity’s pull, and the longer route across space has delayed the light’s arrival at Earth. That light is predicted to finally reach Earth in 2037.

Stay tuned.

Video Credits: NASA / ESTEC / STScI / Greg T. Bacon (STScI)

Messier 96

A galactic maelstromThis is Messier 96, a spiral galaxy a bit more than 35 million light-years away in the constellation of Leo (The Lion). It is roughly the same mass and size as the Milky Way, but unlike our more or less symmetrical galaxy, M96 is lopsided. Its dust and gas are unevenly spread throughout its weak spiral arms, and its core is not exactly at the apparent galactic center. Its arms are also asymmetrical, perhaps because of the gravitational pull of other galaxies within the same group as Messier 96.

Image Credit: ESA / NASA

A White Dwarf and Its Nebula

This is the planetary nebula NGC 3918, a brilliant cloud of colorful gas in the constellation of Centaurus, roughly 4,900 light-years from Earth. In the center of the cloud of gas lies a tiny star, the dying remnant of a red giant. When such a star dies, huge clouds of gas are ejected from its surface before collapses to become a white dwarf. Intense ultraviolet radiation from the tiny remnant star causes the surrounding gas cloud to glow.

NGC 3918 has a distinctive eye-like shape with a bright inner shell of gas and a more diffuse outer shell that extends far from the nebula and looks as if it could be the result of two separate irruptions of gas. However, studies of the object suggest that the two cloud components were formed at the same time but are being blown from the star at different speeds. The powerful jets of gas emerging from the ends of the large structure are estimated to be shooting away from the star at speeds of up to 350,000 km/h/

Image Credit: ESA / NASA

The Cat’s Eye

3000 light-years away from Earth, a dying star is throwing off shells of glowing gas. This picture taken by the Hubble Space Telescope shows that the Cat’s Eye Nebula is one of the most complex planetary nebulae. The Cat’s Eye is so strangely complex that astronomers suspect the bright central object might be a binary star system. Planetary nebula is a term used to describe this general class of objects, but it is somewhat misleading. While these nebulae appear round and planet-like in small telescopes, more powerful instruments reveal them to be stars surrounded by cocoons of gas blown off in the later stages of stellar evolution.

Image Credit: NASA

Seeing Quintuple

This Hubble image shows the light from a distant quasar being gravitationally lensed by a pair of closer galaxies. The quasar shows up in five places in the image. The four bright spots are obvious. The fifth is a dark spot near the center caused by an interference effect resulting from two galaxies bending the light.

Video Credit: ESA

IC 5063

IC 5063 is a galaxy about 156 million light-years away. The interplay of light and shadow we see in the galaxy is probably caused by light blasted by jets fro##a supermassive black hole smacking into a dust ring buried deep inside the core. Light streams through gaps in the ring, creating the brilliant cone-shaped rays, but denser patches block some of the light, casting long, dark shadows through the galaxy. Sunlight streaming through clouds at sunset can create a similar effect, creating a mixture of bright rays and dark shadows formed by beams of light scattered by the atmosphere.

Image Credit: NASA / ESA

Gravitational Lensing

Gravitational lensing occurs when light from a distant galaxy is bent by the gravitational pull of an intervening astronomical object. In this image assembled from multiple observations by the Hubble Space Telescope a relatively nearby galaxy cluster (MACSJ0138.0-2155) has lensed the galaxy (MRG-M0138) which is located 10 billion light-years from us.

Image Credit: NASA / ESA

Hubble Is Back In Business

These images are among the first from Hubble after its return to full science operations. On the left is ARP-MADORE2115-273, a rarely observed example of a pair of interacting galaxies. On the right is ARP-MADORE0002-503, a large spiral galaxy with unusual spiral arms. Most disk galaxies have an even number of spiral arms, but this one has three.

Image Credits: Science—NASA / ESA / STScI / Julianne Dalcanton (UW)
Image processing—Alyssa Pagan (STScI)

A Pair of Different Galaxies

This image taken with Hubble’s Wide Field Camera 3 shows a pair of dissimilar galaxies. The one in the upper left is the lenticular galaxy cataloged as 2MASX J03193743+4137580. The spiral galaxy in the lower right has the shorter designation of UGC 2665. They’re both about 350 million light-years away.

Image Credit: NASA / ESA

Mergers and Acquisitions: Coming Attractions

MRK 1034This pair of galaxies, called MRK 1034, lies in the constellation of Triangulum (The Triangle) in the northern sky. The two similar galaxies, PGC 9074 and PGC 9071, are close enough to one another to be tied together by gravity, but because we are seeing them as they are just beginning to interact gravitationally, there aren’t any large distortions noticeable. Yet. Wait a few hundred million years.

We see both spiral galaxies top down from our point of view. At the bottom PGC 9074 shows a bright bulge and two spiral arms tightly wound around its nucleus, features which classify it as a type Sa galaxy. PGC 9071 isa type Sb galaxy with a fainter bulge and the spiral arms further apart. The spiral arms of both show dark patches of dust mixed with blue clusters of recently-formed stars. Older, cooler stars can be found in the glowing, compact yellowish bulge towards the galactic centers, and each galaxy is surrounded by a much fainter round halo of old stars.

So what would we likely see after waiting a few hundred million years? As these two neighbors attract each other, the process of star formation will be increased, and tidal forces will throw out long tails of stars and gas. Eventually, the interacting galaxies should merge together into a new, larger galaxy.

Image Credit: NASA