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All disk galaxies rotate once every billion years
Astronomy ^ | 3/13/18 | Jake Parks

Posted on 09/29/2018 4:50:31 AM PDT by LibWhacker

All disk galaxies rotate once every billion years

By Jake Parks  |  Published: Tuesday, March 13, 2018
a1
Grand spiral galaxy (NGC 1232).
FORS/8.2-meter VLT Antu/ESO
In a study published March 9 in The Monthly Notices of the Royal Astronomical Society, astronomers announced the discovery that all disk galaxies rotate about once every billion years, no matter their size or mass.

“It’s not Swiss watch precision,” said Gerhardt Meurer, an astronomer from the International Centre for Radio Astronomy Research (ICRAR), in a press release. “But regardless of whether a galaxy is very big or very small, if you could sit on the extreme edge of its disk as it spins, it would take you about a billion years to go all the way round.”

“Discovering such regularity in galaxies really helps us to better understand the mechanics that make them tick,” he said. “You won’t find a dense galaxy rotating quickly, while another with the same size but lower density is rotating more slowly.”

To carry out the study, the researchers determined the radial velocities of neutral hydrogen in the outer disks of a plethora of galaxies — ranging from small dwarf irregulars to massive spirals. These galaxies differed in both size and rotational velocity by up to a factor of 30. With these velocity measurements, the researchers were able to calculate the rotational period of their sample galaxies, which led them to conclude that the outer rims of all disk galaxies take roughly a billion years to complete one rotation. However, the researchers note that further research is required to confirm the clock-like spin rate is a universal trait of disk galaxies and not just a result of selection bias.  

Based on theoretical models, the researchers also expected to find only sparse populations of young stars and interstellar gas on the outskirts of these galaxies. But instead, they discovered a significant population of much older stars mingling with the young stars and gas.

“This is an important result because knowing where a galaxy ends means we astronomers can limit our observations and not waste time, effort, and computer processing power on studying data from beyond that point,” said Meurer. “So because of this work, we now know that galaxies rotate once every billion years, with a sharp edge that’s populated with a mixture of interstellar gas [and] both old and young stars.”

Considering new generations of radio telescopes — like the long-anticipated Square Kilometer Array (SKA) — will produce massive amounts of data, the fact that researchers now have a good idea where a galaxy’s edge lies should also help them significantly reduce the power required to sort through such data.

“When the SKA comes online in the next decade,” Meurer said, “we’ll need as much help as we can get to characterize the billions of galaxies these telescopes will soon make available to us.

Astronomers discovered that all disk galaxies rotate once every billion years, no matter their size.

ICRAR



TOPICS: Astronomy; Science
KEYWORDS: astronomy; billion; disk; galaxies; rotate; science
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To: LibWhacker
I guess that there is a difference between spiral and disk galaxies...wonder what frequency disk galaxies do/don't adhere to.

Seems that the bigger the galaxy, the faster the spin...maybe due to the dynamics of the extra mass...

21 posted on 09/29/2018 7:02:38 AM PDT by trebb (So many "experts" with so little experience in what they preach....even here...)
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To: Moonman62
Oh, that's it, thank you! I thought I was losing my mind. Obviously, stars orbiting Sgr A* up close and personal don't take 250M years go around it.

But I wonder if this new finding is going to tell them anything about dark matter that they didn't know before? I mean, it seems like it's a pretty significant discovery... The outer regions of every disk galaxy rotating once every billion years, regardless of mass, etc. Really bizarre.

22 posted on 09/29/2018 7:11:56 AM PDT by LibWhacker
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To: Campion

No problem. We’re all here to try to help each other understand. Don’t hesitate to correct me if you find me messing up on something!


23 posted on 09/29/2018 7:15:45 AM PDT by LibWhacker
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To: LibWhacker

I don’t think it’s all that unexpected. My unscientific feeling is this just confirms what they already know, dark matter dominates. And the outer bands only contain a small amount of the mass in a galaxy. Notice in my graphic that the measurement uses hydrogen gas for the outer bands.

I think the value of this new finding is represented by this statement:

“This is an important result because knowing where a galaxy ends means we astronomers can limit our observations and not waste time, effort, and computer processing power on studying data from beyond that point,” said Meurer.


24 posted on 09/29/2018 7:23:15 AM PDT by Moonman62 (Give a man a fish and he'll be a Democrat. Teach a man to fish and he'll be a responsible citizen.)
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To: trebb
Spiral galaxies are one type of disk galaxy.

Other than that, I'm just really having a hard time wrapping my head around this.

I see the sun's coming up. Time for me to hit the sack. Cheers!

25 posted on 09/29/2018 7:33:47 AM PDT by LibWhacker
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To: Moonman62

You’re probably right about that. Whenever I read about something in science that I don’t understand (which is quite often nowadays), I expect it’ll to lead to some kind of breakthrough. It never does, lol.


26 posted on 09/29/2018 7:37:28 AM PDT by LibWhacker
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To: LibWhacker
The fact that they form spiral patterns suggests the galaxies does not rotate as solid disks.

27 posted on 09/29/2018 7:40:04 AM PDT by BitWielder1 (I'd rather have Unequal Wealth than Equal Poverty.)
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To: LibWhacker

They get an even tan that way.


28 posted on 09/29/2018 7:49:14 AM PDT by Larry Lucido
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To: LibWhacker

“It’s as if every disk-like galaxy were a giant phonograph record, everything rotating in lock-step.”

Not so.


29 posted on 09/29/2018 8:56:59 AM PDT by Born to Conserve
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To: cranked

That is 10 million human lifetimes to rotate around disk galaxy.


30 posted on 09/29/2018 9:09:54 AM PDT by TheNext (Anonymous Source)
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To: TheNext

Your 10 millionth great grandparent lived in the identical cosmic neighborhood.


31 posted on 09/29/2018 9:12:01 AM PDT by TheNext (Anonymous Source)
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To: Born to Conserve

You are right, thx! I read that somewhere... should’ve known!


32 posted on 09/29/2018 9:30:18 AM PDT by LibWhacker
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To: LibWhacker

Check this out...

https://gizmodo.com/5953694/this-stunning-nasa-simulation-shows-a-galaxys-entire-life-history


33 posted on 09/29/2018 9:33:23 AM PDT by Born to Conserve
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To: Born to Conserve

Wow, very cool! Loved it.


34 posted on 09/29/2018 3:50:15 PM PDT by LibWhacker
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To: LibWhacker
#1 The Milky Way needs a new black hole to power itself.
Blnk
35 posted on 09/29/2018 4:39:07 PM PDT by minnesota_bound
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To: SunkenCiv

*ping*


36 posted on 09/29/2018 5:09:38 PM PDT by fieldmarshaldj ("It's Slappin' Time !")
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To: fieldmarshaldj; brytlea; cripplecreek; decimon; disndat; KoRn; Grammy; steelyourfaith; Mmogamer; ...
Thanks fieldmarshaldj. APoD ping.

37 posted on 09/29/2018 11:54:54 PM PDT by SunkenCiv (www.tapatalk.com/groups/godsgravesglyphs/, forum.darwincentral.org, www.gopbriefingroom.com)
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To: ImJustAnotherOkie
> The Milky Way is only in 2nd gear.

Are you saying the Milky Way is the "little Nash Rambler" of galaxies?

"BEEP BEEP" - https://www.youtube.com/watch?v=ayTJtVzHOLs

38 posted on 09/30/2018 11:06:07 AM PDT by dayglored ("Listen. Strange women lying in ponds distributing swords is no basis for a system of government.")
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To: ImJustAnotherOkie
The Milky Way is only in 2nd gear.

A Nash Rambler?

39 posted on 10/01/2018 6:48:20 AM PDT by null and void (The big problem is that the republicans don't keep their campaign promises and the democrats do!)
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To: dayglored

GMTA


40 posted on 10/01/2018 6:50:59 AM PDT by null and void (The big problem is that the republicans don't keep their campaign promises and the democrats do!)
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