Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Milky Way is warped

  • Please log in to reply
5 replies to this topic

#1 DSOGabe

DSOGabe

    Apollo

  • *****
  • topic starter
  • Posts: 1,057
  • Joined: 02 Aug 2019
  • Loc: El Paso, TX

Posted 17 May 2021 - 12:12 PM

I read an article in either Astronomy or S&T recently where astronomers think the disk is warped. I believe they think the LMC is responsible. 

Then I read another article that one of the galaxies in the Leo Triplet is warped due to gravitational forces between it and the other ones. Those galaxies are about 3 or so million LY from each other.

So, I wonder if the apparent warpage in the Milky Way can really be blamed on the LMC or is Andromeda the guilty party?



#2 Pokemoncrusher1

Pokemoncrusher1

    Vostok 1

  • -----
  • Posts: 126
  • Joined: 11 Dec 2020

Posted 17 May 2021 - 01:45 PM

andromeda is much farther than LMC but has much more mass. Knowing approximate distances you can maybe calculate the pull on each other and determine if the effect of the mass vs the distance of one or the other is affecting the galaxy more



#3 TOMDEY

TOMDEY

    Cosmos

  • *****
  • Posts: 9,714
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 17 May 2021 - 01:50 PM

The LMC seems to be much more massive than they originally thought and would account for that. The N-Body Problem is still substantially-intractable to this day... and probably will be forever. Dynamic, most always unstable and tiny variations in the initial conditions change down-stream states rather explosively. The butterfly effect is entrenched. And since we are pretty ignorant of even current state --- makes projections into the past or future --- not much better than weather forecasting! Maybe that's a good thing. It means I may be alive and Supreme Ruler of Earth fifty years from now.

 

[I intended to do my thesis on the N-Body Problem but my advisor talked me out of it... very sound advice! Instead, I did it on geodesy, astrometry, and such arcane conniptions; earned the degree; the rest is history.   Tom

Attached Thumbnails

  • 33 thumbnail 50 nasa interacting galaxies.jpg

  • TrustyChords likes this

#4 TrustyChords

TrustyChords

    Mariner 2

  • *****
  • Posts: 290
  • Joined: 26 Jun 2017

Posted 17 May 2021 - 02:19 PM

The LMC seems to be much more massive than they originally thought and would account for that. The N-Body Problem is still substantially-intractable to this day... and probably will be forever. Dynamic, most always unstable and tiny variations in the initial conditions change down-stream states rather explosively. The butterfly effect is entrenched. And since we are pretty ignorant of even current state --- makes projections into the past or future --- not much better than weather forecasting! Maybe that's a good thing. It means I may be alive and Supreme Ruler of Earth fifty years from now.

 

[I intended to do my thesis on the N-Body Problem but my advisor talked me out of it... very sound advice! Instead, I did it on geodesy, astrometry, and such arcane conniptions; earned the degree; the rest is history.   Tom

Is there any chance the LMC has passed through the Milky Way in the past (which gobbled away some of its structure)?



#5 TOMDEY

TOMDEY

    Cosmos

  • *****
  • Posts: 9,714
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 17 May 2021 - 03:12 PM

Is there any chance the LMC has passed through the Milky Way in the past (which gobbled away some of its structure)?

Used to be thought that it has looped around several times already --- but now they are inclined to believe that this is its first swipe at us, and that it didn't plow in or through... yet. At least that's what they're saying now.    Tom


  • TrustyChords likes this

#6 Tony Flanders

Tony Flanders

    Hubble

  • *****
  • Posts: 19,664
  • Joined: 18 May 2006
  • Loc: Cambridge, MA, USA

Posted 17 May 2021 - 05:05 PM

andromeda is much farther than LMC but has much more mass. Knowing approximate distances you can maybe calculate the pull on each other and determine if the effect of the mass vs the distance of one or the other is affecting the galaxy more

Presumably this is due to tidal "force" rather than simple gravitational pull. My intuition says that simple gravitational pull would shift the Milky Way's position without altering its structure. Though I can't claim that my intuition is infallible in cases like this.

 

Tides are the difference in gravitational pull depending where you are in the pulled-on object, and decrease with the cube of the distance between the two objects rather than the square. Since M31 is about 15 times more distant than the LMC, it would need to be 15^3 ~= 3000 times more massive than the LMC to have equal tidal effect. In fact the discrepancy is nowhere near that great.

 

For what it's worth, current models of galaxy motion suggest that both M31 and the LMC are now closer to the Milky Way than they ever have been before.


  • TrustyChords, Voyager 3 and EricSi like this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics