Comments on: Alien Sun followup

By: Mapnut

Mapnut — Fri, 29 Jun 2007 16:39:47 +0000

It seems to me that Dr. Majewski has been somewhat victimized by his tendency to use colorful language, such as “who’s the bully” “eating its smaller neighbors”, “stars are now raining down on our present position”, and “debris trail”, which implies massive destruction. This might attract people looking to create a sensation, and help fool the gullible by distorting the time frame. If a star from Saggitarius was passing near us at a large angle to the galactic plane, we could hardly see the change in its position in our lifetime, if I’m not mistaken (speaking of amateur observers, of course).

By: The Bad Astronomer

The Bad Astronomer — Fri, 29 Jun 2007 16:34:49 +0000

Geraint, you have made a legitimate point, so I posted again about this.

By: Irishman

Irishman — Fri, 29 Jun 2007 15:32:01 +0000

Nice followup, with the link to the University of Virginia page. That animation was interesting to rotate.

That page also answered my other question, why is the Sag Dwarf galaxy stretched into a Q shape around the MW? The other animation on that page shows the dwarf galaxy as it rotates while orbiting the MW. The gravitic and inertia forces stretch and elongate the galaxy, swinging some parts wider than other parts, and creating the long streamer swirls that don’t follow in a neat circle. Cool!

I still think you might be begging the question with that comment about the Sun being on the other side of the MW 50 Mya.

By: CS

CS — Fri, 29 Jun 2007 14:19:33 +0000

Heng:

The reason the Milky Way is not distorted is that it is far more massive than the Sagittarius dwarf galaxy. Think of a comet and the Sun: the comet’s orbit is highly dependent upon the Sun, but the Sun’s motion is hardly perturbed by a passing comet. The number of particles used for each of the two galaxies in the simulation is not indicative of the masses involved (i.e. 1 MW particle does not equal 1 Sgr particle).

By: Sergeant Zim

Sergeant Zim — Fri, 29 Jun 2007 12:26:28 +0000

[quote]â€If people had infrared-sensitive eyes, the entrails of Sagittarius would be a prominent fixture sweeping across our sky,â€ Majewski said.[/quote]

Pardon me, but isn’t infrared the portion of the EM spectrum that is most efficiently filtered out by our atmosphere?(Thus the Spitzer telescope) Ergo, if we were to see in IR, we still wouldn’t see Saggy at all…

By: heng

heng — Fri, 29 Jun 2007 11:22:02 +0000

sorry for doubleposting, but another thing i didn`t get with the original article linked here is:

[quote]”If people had infrared-sensitive eyes, the entrails of Sagittarius would be a prominent fixture sweeping across our sky,” Majewski said.[/quote]
so far so good. but on the image on the bottom of the same page there is a [quote]2MASS view of the entire sky[/quote]… meaning: a full(!) sky mosaic in 2micron infrared… yet i don`t see _any_ of the structures depicted in the video…

something doesn`t add up in my head without further explanation…
could you provide some?

By: heng

heng — Fri, 29 Jun 2007 11:11:00 +0000

hmm… a question to the video fly-around:
why isn`t the milkyway distorted?

any quasi-simulations and depictions of collision events _both_ systems tend to be distorted… is in the video “our” galaxy deliberately left untouched in a more-or-less generic perfect spiral form?
i know, e.g. that we don`t know the layout of a pretty large part of the plane (beyond the hub)…