Are the Milky Way’s borders expanding?

Astronomy ^ | 3 Apr, 2018 | Amber Jorgenson

[MtnClimber]

Hundreds of billions of stars make up the barred spiral galaxy that we call home. The Milky Way’s 100,000 light-year diameter houses stars of different masses, luminosities, and ages, with new stars constantly being added to the mix. Star formation isn’t showing signs of slowing down, and this includes births at the outer edges of the galaxy. Could these young stars forming near the galactic edge be expanding the size of the Milky Way?

A team of researchers, led by Ph.D. candidate Cristina Martínez-Lombilla of the Instituto de Astrofísica de Canarias in Spain, presented research supporting this idea at the European Week of Astronomy and Space Science on April 3.

Older, lower-mass stars are abundant near the galaxy’s center and in the halo that looms around the Milky Way’s disk, while younger stars form within the disk itself (the spiral arms). Because some of these hotbeds for star formation lie near the disk’s edge, the researchers set out to study how these new additions could impact the Milky Way’s dimensions.

However, the issue with studying the expansion of the Milky Way is our location — a comprehensive viewpoint is difficult to obtain when you’re within the object of observation. To get a clearer perspective, the researchers studied nearby spiral galaxies with similar properties to our own. In particular, they set their sights on NGC 4565 ............

They measured the light emitted from these areas to determine the types of stars present, which were mainly young blue stars, and also measured their movement within the region to determine how long it takes them to start traveling outward. Their calculations show that, based on star motions, galaxies similar to the Milky Way are expanding by about 1,640 feet (500 meters) per second.

[broken_arrow1]

Is it an observer thing related to general relativity? If we were in another galaxy, like Andromeda and made the measurements of the Milky Way galaxy, maybe expansion would be obvious. Like an observer in a rocket ship traveling at the speed of light, nothing looks out-of-the-ordinary in his rocket ship; however, he would suggest everything else is changing...

[Wuli]

Thanks. You win my Morning Chuckle prize.

[Wuli]

LOL You’re like me on this one. When I make such an error I make the excuse that sometimes my fingers type faster than my brain thinks.

[SunkenCiv]

Thanks fieldmarshaldj.

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In the 'Great Debate' of 1920, Shapley was just plain wrong about the structure of the Universe, which he said was the same as our galaxy, a ridiculous boner given the actual size of the universe. Curtis merely underestimated the size of the Milky Way, but said our galaxy was one of many and that the spiral nebulae were other galaxies and very far off. Mostly both are said to be a little right and a little wrong, given what is now known, and that the debate was a draw, but it is clear and obvious that while Shapley was overstating the size of the Milky Way by about three times, Curtis was underestimating it by three times, and had everything else correct. My guess is, Shapley's disgraceful hardcore commie politics are the main reason he's spoken of with such high regard.

• The Curtis-Shapley debate

[Fred Hayek]

There would still be some deflection due to gravity.

[hal ogen]

Dude, I plan on still being here.

[Telepathic Intruder]

There are many effects resulting from galaxy collision, but colliding stars is not one of them. Gravitational distortion destroys the spiral structures if they’re roughly equally sized, else one just destroys the other. Galaxies are also made of gas, and that does collide, resulting in a sudden starburst where all the gas in the disk region is converted to stars. After that, no more star formation, but a huge number of additional population II stars (low metallicity). This is how elliptical galaxies form. Eventually all the large bright high-mass but short lifetime stars die off and all you have are small reddish stars.

[Bubba Ho-Tep]

(spoken)
Whenever life gets you down, Mrs. Brown,
And things seem hard or tough,
And people are stupid, obnoxious or daft,
(sung)
And you feel that you've had quite eno-o-o-o-o-ough,

Just remember that you're standing on a planet that's evolving
And revolving at 900 miles an hour.
It's orbiting at 19 miles a second, so it's reckoned,
The sun that is the source of all our power.
Now the sun, and you and me, and all the stars that we can see,
Are moving at a million miles a day,
In the outer spiral arm, at 40,000 miles an hour,
Of a galaxy we call the Milky Way.

Our galaxy itself contains a hundred billion stars;
It's a hundred thousand light-years side to side;
It bulges in the middle sixteen thousand light-years thick,
But out by us it's just three thousand light-years wide.
We're thirty thousand light-years from Galactic Central Point,
We go 'round every two hundred million years;
And our galaxy itself is one of millions of billions
In this amazing and expanding universe.

(waltz)

Our universe itself keeps on expanding and expanding,
In all of the directions it can whiz;
As fast as it can go, at the speed of light, you know,
Twelve million miles a minute and that's the fastest speed there is.
So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth;
And pray that there's intelligent life somewhere out in space,
'Cause there's bugger all down here on Earth!

[mikrofon]

We'll have to see if the Preservers want to beef up the barrier…

[Redcitizen]

The Milky Way seemed bigger back then because your borders were much smaller. (Meaning you were kid sized).

[central_va]

Who f-ing cares?

[Songcraft]

Yes.