New study shows Small Magellanic Cloud is two smaller galaxies | Hacker News Reader

New study shows Small Magellanic Cloud is two smaller galaxies

phys.org

108 pointswglb27 comments

It is actually doubtful that the Magelanic Clouds orbit the Milky Way.

"Astronomers have long assumed that the Magellanic Clouds have orbited the Milky Way at approximately their current distances, but evidence suggests that it is rare for them to come as close to the Milky Way as they are now. Observation and theoretical evidence suggest that the Magellanic Clouds have both been greatly distorted by tidal interaction with the Milky Way as they travel close to it."

https://en.m.wikipedia.org/wiki/Magellanic_Clouds

"They are merely flying by at high speed and that this close encounter is a first time occurrence. The Magellanic Clouds have enough velocity to escape the Milky Way and fly about the local group. They will be changed by the effect of the close encounter and undergo a burst phase of star formation."

https://stargazehawaii.com/the-magellanic-clouds-are-not-in-...

Shouldn't gravitational friction from dark matter slow the MCs down enough that they won't escape?

Given dark matter isn't yet well characterised, there definitely isn't a "should" in what we know.

But I'd be surprised, because if it was even a possibility that it might be able to apply a friction force large enough to be relevant to to the relative motion of the galaxies, I think a lot of people would be talking about this in the same breath as the bullet cluster.

I do envy the southern sky for the SMC and LMC. (A good photo is in the wikipedia article https://en.wikipedia.org/wiki/Small_Magellanic_Cloud)

I've been to the southern hemisphere twice with the second one being exactly 10 days later because I filled in for someone else for the second trip. The first was to Australia during a full moon, but the second was to New Zealand during a new moon. I was like a giddy little school boy when I took my first picture of the LMC. After getting my bearings on LMC/SMC and Alpha/Beta Centauri, I was able to shoot a few timelapses of the rotation and see how not having a singular "South Star" was still able to see the "center" of the rotation. Unfortunately, these trips were not a night sky viewing event, otherwise, I would have spent much more time checking things out. I did take the time I could though

Thank you! Here is the money shot, with the Milky Way (please excuse me Kiwis) upside down and the two Magellanic clouds showing: https://en.wikipedia.org/wiki/File:Panoramic_Large_and_Small...

I just always thought they'd be similar to the Andromeda galaxy - visible just barely if you know where to look under perfect conditions. I had no idea!

It's OK to call the LMC "large", because it is. But calling the SMC "small" is decidedly not. And, they're not clouds, either.

This is a unique opportunity to give these two lesser galaxies better names. The nearer one could be the "Lesser Magellanic Nebula". The far one could be the "Cryptic Magellanic Nebula". Then the LMC gets "Greater Magellanic Nebula". Andromeda may stay Andromeda, unless the San people in Botswana have a name for it that we could pronounce.

People living in the southern hemisphere for lo so many millennia knew they were there all along, before Magellan drifted past. Just "Greater Southern Nebula" etc. instead? Maybe ask the San about those too. Or the Yaghan in Tierra Del Fuego. Or Australian aboriginals. All deserve reparations.

The Small Magellenic Cloud was, heretofore, presumed to contain about 3 billion stars, vs. 30 billion for the Large Magellenic Cloud, and 100 billion stars for the Milky Way.

The Small Magellenic Cloud was, heretofore, estimated to be about 18,900 light years in diameter.

Nebula clusters are generally on the order of magnitude of a few thousand stars at most, and only hundreds of lightyears in size.

However the division of the two smaller parts of the SMC works out, I believe both deserve more than simple appelation of "nebulae."

The point is that "cloud" is objectively the wrong name. As is "small".

So as a replacement for the word “cloud” you’re suggesting instead the Latin word “nebula”, meaning “cloud”

Doesn't this level of literalism in taxonomy feel a bit sterile and unnecessary? It sure does to me.

This just in: the Milky Way is not comprised of milk :(

The Milky Way is the only galaxy known to contain milk. It's also the only galaxy known to contain Milky Way bars. The name definitely fits.

The Milky Way is also the only known galaxy to have ever contained Magellan.

https://en.wikipedia.org/wiki/Ferdinand_Magellan

THIS is why I love HN!

Does this suggest an extra-galactic origin for The Moon?

If we're going to rename it, my proposal would be "Two Small Galaxies In A Trenchcoat".

The SMC is very close to the Milky Way.

Imagine a plan view: You see the Milky Way in its full width, then a gap, then the SMC. That gap is the width of two Milky Ways at most. Not 200 or 2000. Just 2.

For Andromeda, that gap is about 24. Despite the mind-bogglingly large distances involved, there's a funny sense in which inter-galactic space feels less empty than solar space or inter-stellar space.

Direct arxiv link, interesting stuff! https://arxiv.org/abs/2312.07750

I wonder if, from the more distant dwarf galaxy, if it would look like the Milky Way and the closer dwarf galaxy are the same galaxy.

...in a trenchcoat

Please don't post memes to HN.

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