The Dragon's Egg Nebula, NGC 6164 // Daniel Stern

Young Stars, Stellar Jets via NASA https://ift.tt/mUE9hQK

Did you know that there are 5 known dwarf planets in our solar system? Everyone knows Pluto, but there is also Ceres, Haumea, Makemake and Eris.

Info from: https://www.iau.org/public/themes/pluto/#n6

Interacting galaxy

Interacting galaxies (colliding galaxies) are galaxies whose gravitational fields result in a disturbance of one another. An example of a minor interaction is a satellite galaxy’s disturbing the primary galaxy’s spiral arms. An example of a major interaction is a galactic collision, which may lead to a galaxy merger.

A giant galaxy interacting with its satellites is common. A satellite’s gravity could attract one of the primary’s spiral arms, or the secondary satellite’s path could coincide with the position of the primary satellite’s and so would dive into the primary galaxy (the Sagittarius Dwarf Elliptical Galaxy into the Milky Way being an example of the latter). That can possibly trigger a small amount of star formation. Such orphaned clusters of stars were sometimes referred to as “blue blobs” before they were recognized as stars.

Colliding galaxies are common during galaxy evolution. The extremely tenuous distribution of matter in galaxies means these are not collisions in the traditional sense of the word, but rather gravitational interactions.

Colliding may lead to merging if two galaxies collide and do not have enough momentum to continue traveling after the collision. In that case, they fall back into each other and eventually merge into one galaxy after many passes through each other. If one of the colliding galaxies is much larger than the other, it will remain largely intact after the merger. The larger galaxy will look much the same, while the smaller galaxy will be stripped apart and become part of the larger galaxy. When galaxies pass through each other, unlike during mergers, they largely retain their material and shape after the pass.

Galactic collisions are now frequently simulated on computers, which use realistic physics principles, including the simulation of gravitational forces, gas dissipation phenomena, star formation, and feedback. Dynamical friction slows the relative motion galaxy pairs, which may possibly merge at some point, according to the initial relative energy of the orbits.

Astronomers have estimated the Milky Way galaxy, will collide with the Andromeda galaxy in about 4.5 billion years. It is thought that the two spiral galaxies will eventually merge to become an elliptical galaxy or perhaps a large disk galaxy.

Source

Image credit: NASA/ESA & Hubble (procesed by:  Steve Byrne & Judy Schmidt)

Animation

The Dolphin Head Nebula (Sh2-308, right) and Sh2-303 (left) // Jim Thommes

The Hidden Galaxy, IC 342 // Ondřej Pešák

This striking image captures the interacting galaxy pair known as Arp-Madore 2339-661, so named because they belong to the Arp-Madore catalogue of peculiar galaxies. However, this particular peculiarity might be even odder than first meets the eye, as there are in fact three galaxies interacting here, not just two. 

The two clearly defined galaxies are NGC 7733 (smaller, lower right) and NGC 7734 (larger, upper left). The third galaxy is currently referred to as NGC 7733N, and can actually be spotted in this picture if you look carefully at the upper arm of NGC 7733, where there is a visually notable knot-like structure, glowing with a different colour to the arm and obscured by dark dust. 

Credit: ESA/Hubble & NASA

Our supply of eclipse glasses is running very low.

Wed. Oct. 22: We'll be open tonight from 7 - 8 pm. We expect some clouds, but we should still be able to catch some nice glimpses of the sky. Saturn is still the star of the show!

This animation portrays the creation of the cat’s tail in the southwest portion of Beta Pic’s secondary debris disk, estimated to span 10 billion miles. Read today's #AAS243 release to learn more: http://webbtelescope.pub/3RXt9Nx