Picture Of The Day!

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

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

Skyshark

Man sees what he wants to see, and so it is with the Dark Nebula LDN 1235. This collection of dust in the constellation Cepheus is very reminiscent of a shark. At just 650 light years away, it is just around the corner.

Object type: Dark nebula

Constellation: Cepheus

Total exposure: 720 minutes

Image data:

- RGB 144 x 300s / Gain 100

- 25 flats

- 25 Bias

- 25 Darks

Setup:

- Skywatcher 150/750 F5 PDS

- Omegon 571C

- Skywatcher EQ6R Pro

- Two Asi 178mm as guide cam

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Picture of the Day!

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Image credit: Helge Buesing

Wed. Nov. 15 - Tonight's forecasts are inconsistent- we'll wait a few hours to decide if we'll open.

NASA Science

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Article of the Day!

“Dust in the Stellar Wind: A Cosmological Primer” by Pat Brennan

Astronomy Picture of the Day from NASA

Image taken by Alexandros Maragos

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NASA Science

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