Sci/Tech Milky Way twice as large as previously thought

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Zeph

TMMAC Addict
Jan 22, 2015
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Despite residing in it, it’s hard for us to know exactly how big the Milky Way is. But new research has found that our galaxy is bigger than previously thought. Using a large survey of stars instead of just models (as previous researchers did), astronomers have now determined the disk of our galaxy to be 200,000 light-years across — twice as large as was believed a decade ago.

Astronomers know the Milky Way to be a spiral galaxy with a flat central disk composed of spiraling arms and a sparse outer cloud of stars called the halo. Most of the stars are found in the disk, which rapidly thins out at the edges. The size of the galaxy is measured from the point at which the number of stars in the disk significantly drops, so finding disk stars is key to determining the Milky Way’s size.

Fortuitously, disk stars tend to be much younger than the halo stars. Since stars gradually build up elements over generations, the disk stars’ composition can be differentiated from the halo stars, allowing astronomers to figure out which stars belong to which population.

An annotated map showing the Milky Way's structure, based on measurements to distant stars and other objects.
NASA
Finding the outer reaches
With a process known as spectroscopy, researchers from the Instituto de Astrofísica de Canarias and at the National Astronomical Observatories of Beijing studied the chemical composition of over 4,600 stars from two surveys, APOGEE and LAMOST, and mapped out which stars are part of the disk and which belong to the halo. The results, published May 7 in the journal Astronomy and Astrophysics, clearly show disk stars much farther from center of the galaxy than before.

“Certainly, one would expect the existence of stars at very far distances from the galactic center, as part of the halo,” says Martín López Corredoira, lead author on the paper and researcher at Instituto de Astrofísica de Canaria. “But, as far as we know, nobody could previously say that stars [farther than 81,000 light-years] are confirmed spectroscopically to belong to the disk.”

Bigger, not heavier
The researchers still believe the density of stars at the edge tapers off in an exponential manner — just farther away than previously thought. Although its diameter has been supersized, the Milky Way is still smaller than its neighbor Andromeda, which measures over 220,000 light-years across.

While our galaxy is looking larger, it’s not putting on much weight. Because the outer reaches are much less dense than the center of the galaxy, the additional area is only sparsely populated with stars. These few extra stars are only a drop in the bucket compared to the rest of the galaxy, so overall the mass of the Milky Way remains largely unchanged.


Supersize me
 

kaladin stormblessed

Nala fanboy
Apr 24, 2017
17,627
20,132


Despite residing in it, it’s hard for us to know exactly how big the Milky Way is. But new research has found that our galaxy is bigger than previously thought. Using a large survey of stars instead of just models (as previous researchers did), astronomers have now determined the disk of our galaxy to be 200,000 light-years across — twice as large as was believed a decade ago.

Astronomers know the Milky Way to be a spiral galaxy with a flat central disk composed of spiraling arms and a sparse outer cloud of stars called the halo. Most of the stars are found in the disk, which rapidly thins out at the edges. The size of the galaxy is measured from the point at which the number of stars in the disk significantly drops, so finding disk stars is key to determining the Milky Way’s size.

Fortuitously, disk stars tend to be much younger than the halo stars. Since stars gradually build up elements over generations, the disk stars’ composition can be differentiated from the halo stars, allowing astronomers to figure out which stars belong to which population.

An annotated map showing the Milky Way's structure, based on measurements to distant stars and other objects.
NASA
Finding the outer reaches
With a process known as spectroscopy, researchers from the Instituto de Astrofísica de Canarias and at the National Astronomical Observatories of Beijing studied the chemical composition of over 4,600 stars from two surveys, APOGEE and LAMOST, and mapped out which stars are part of the disk and which belong to the halo. The results, published May 7 in the journal Astronomy and Astrophysics, clearly show disk stars much farther from center of the galaxy than before.

“Certainly, one would expect the existence of stars at very far distances from the galactic center, as part of the halo,” says Martín López Corredoira, lead author on the paper and researcher at Instituto de Astrofísica de Canaria. “But, as far as we know, nobody could previously say that stars [farther than 81,000 light-years] are confirmed spectroscopically to belong to the disk.”

Bigger, not heavier
The researchers still believe the density of stars at the edge tapers off in an exponential manner — just farther away than previously thought. Although its diameter has been supersized, the Milky Way is still smaller than its neighbor Andromeda, which measures over 220,000 light-years across.

While our galaxy is looking larger, it’s not putting on much weight. Because the outer reaches are much less dense than the center of the galaxy, the additional area is only sparsely populated with stars. These few extra stars are only a drop in the bucket compared to the rest of the galaxy, so overall the mass of the Milky Way remains largely unchanged.


Supersize me
so we are closet to andromeda? Or can we assume that new technology will reveal andromeda to be bigger than previously thought as well?
 

Zeph

TMMAC Addict
Jan 22, 2015
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32,126
so we are closet to andromeda? Or can we assume that new technology will reveal andromeda to be bigger than previously thought as well?
I don't know. I think it's likely we have a better estimate on Andromeda's size because we can view it as a whole in the distance, rather than being a part of the Milky Way. So my best guess would be that Andromeda is the same size, roughly, as the Milky Way and not about to increase in, official, size.
 

sparkuri

Pulse On The Finger Of The Community
First 100
Jan 16, 2015
34,427
46,565
There's go 10,000,000,000 hours of wasted time by people at each other's throats, based on false intel.
Can't wait to argue for another 20 years about time-space, black holes, einstein-rosen bridges, the fabric of existence and inter-dimensional theories based on our current understanding of this dimensions physics.
Until "science" finds we're essentially in a giant snowglobe.
 

sparkuri

Pulse On The Finger Of The Community
First 100
Jan 16, 2015
34,427
46,565
Space is constantly expanding. So isn't it always bigger than we thought?
Many, many people believe ancient scriptures were divine, and explain everything in existence.
King David of Israel wrote this a few thousand years ago, in line with current scientific theory.
"Who coverest thyself with light as witha garment: who stretchest out the heavens like a curtain"
This of course states a creator has created an ever expanding plane.

The book of Enoch is very interesting, assumed to have been read by all writers of Judeo-christian texts as well as Mohammed.
That is an intriguing piece of work seemingly explaining much of our interstellar surroundings.
 

silentsinger

Momofuku
Jun 23, 2015
21,038
14,484
It’s all verifiable......ask Brian cox
It apparently is though! And I'm really pissed off Hawking isn't around for the rest of my life to chime in about it with his wit and humour.

Damn you. if I could have anyone read me a bedtime story if I were sick it would be you, but Cox would be my second choice.
 

Robbie Hart

All Biden Voters Are Mindless Sheep
Feb 13, 2015
49,705
50,710
It apparently is though! And I'm really pissed off Hawking isn't around for the rest of my life to chime in about it with his wit and humour.

Damn you. if I could have anyone read me a bedtime story if I were sick it would be you, but Cox would be my second choice.
He would surely put you to sleep as boring as fuck as his bullshit made up world is