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.

[MtnClimber]

When we collide with Andromeda galaxy in about 3 billion years none of this will matter. Glad I won’t be here to worry if we get slammed by another star!

[null and void]

Still, the night sky will be spectacular!

[cynwoody]

According to the article, the Milky Way’s diameter is 100,000 light-years. That’s about 877 million light-hours. Using the heliopause as the limit of the solar system, its diameter is about 34 light-hours. So, the Milky Way is about 25.8 million solar systems across.

[fieldmarshaldj]

*ping*

[Ciaphas Cain]

I am becoming of an age when eating a Milky Way makes MY borders be expanding.

[ProtectOurFreedom]

And has 100s of billions of stars. That size doesn’t seem large enough to contain that many stars, especially because the galaxy is disc shaped with spiral arms.

[wardaddy]

Yes it’s true

The blue moon just told me

[Telepathic Intruder]

There is actually not much greater chance of stars colliding during a galaxy collision than now. They are pretty much flying around randomly between each other just orbiting the Milky Way. There's just too much space between stars for it to be occur with any reasonable likelihood.

Imagine our star is the size of a marble (1 cm across). Then the nearest star to our sun would be another marble 180 miles away. Double the approximate number of stars due to one galaxy flying through another, and that's still a very small target.

[wardaddy]

You’re a great freeper but even the vaunted Oort Cloud is only 1.87 light years from the sun equating to roughly twice that fin diameter from Oort to Oort

The Oort Cloud occupies a space about half way to our closest star and is affected by gravity from our Sun and that star Proxima Centauri

100,000 A.U. (Distance earth to sun) from Sun to mean Oort vastness

The Heliopause is only 120 A.U. From the Sun to interstellar space though there is argument Sun shock waves go much further

Anyhow....Astronomy is a flame meets moth thing for me ...bores my family

Now discard this entire post because I just noticed you wrote Light Hours not Years...lol...and have no need for my unsolicited correction

I love this stuff

[buckalfa]

Plus I remember when a Milky Way was bigger and only cost five cents.

[MadMax, the Grinning Reaper]

I hope so. Today’s Milky Way bars are much smaller than they were when I was a kid. The same for Snickers and Three Musketeers (my favorite).

“Make Milky Ways Great Again”.

[Beowulf9]

What was the chocolate candy bar that resembled the Chrysler Building? I’ve been trying to find this out for years.

Or should I say light years to make a weak attempt at staying within the subject here...

[Darksheare]

Haven’t seen a Mars bar since my last MRE dropped one in my lap.

[SunkenCiv]

Thanks fmdj, will ping from home!

[Does so]

When we collide with Andromeda galaxy in about 3 billion years none of this will matter.

"Professor, was that millions or billions of years?"

[ClearCase_guy]

borders expanding?

We're going to need an even bigger wall, but don't worry -- Mexico will pay for it.

[ImaGraftedBranch]

How could they know? The light reaching us left before humans created the first telescope.

[wrcase]

I hope Keith Richards has his affairs in order.

[politicianslie]

How could they know? The light reaching us left before humans created the first telescope.

If an object is moving AWAY from us, the light is red shifted by doppler and the relative velocity can be calculated.

If toward us, the object's light is shifted HIGHER and that relative velocity can be calculated.

It's analogous to the siren coming toward us and then away from us as the emergency vehicle passes by us.