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)

The Earth Seen From Space

One of the most famous images of Earth was taken by Voyager 1 when it was 6 billion km from home. The Earth is a single pixel in that picture called The Pale Blue Dot. Voyager 1 was just about 12,000,000 km above Mt. Everest when it took this picture of the Earth and the Moon on 18 September, 1977. The Moon is on the far side of the Earth in this picture which shows East Asia, the Western Pacific, and part of the Arctic. Mt. Everest in hidden from view on the night side of the Earth.

Image Credit: NASA

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)

A Disorganized Dwarf

A distinctly disorganised dwarfUGC 4459’s diffused and disorganized appearance is characteristic of an irregular dwarf galaxy. Because they lack distinctive structure or shape, irregular dwarf galaxies are typically chaotic in appearance, with neither a nuclear bulge (a tightly-packed central group of stars) nor any trace of spiral arms extending from the center of the galaxy.

Image Credit: NASA

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