Milky Way may have a huge hidden neighbour

[Soylent Brice]

A LARGE satellite galaxy may be lurking, hidden from view, next door to our own.

Sukanya Chakrabarti and Leo Blitz of the University of California, Berkeley, suspected that the gravity of a nearby galaxy was causing perturbations that have been observed in gas on the fringes of the Milky Way. "We did a large range of simulations where we varied the mass of the perturber and the distance of closest approach," says Chakrabarti. In the best-fitting simulation, the unseen galaxy has about 1 per cent of the Milky Way's mass, or 10 billion times the mass of the sun.

That's a lot. It means the object has roughly the same mass as the Milky Way's brightest satellite galaxy, the Large Magellanic Cloud (LMC).

Right now, says Chakrabarti, the galaxy is roughly 300,000 light years away from us - about twice as far away as the LMC. But the simulations suggest it follows a highly elongated elliptical path, and about 300 million years ago it swept through our own galaxy just 16,000 light years from the galactic centre - closer in than Earth - disturbing the Milky Way's outskirts as it went.

more: http://www.newscientist.com/article/mg20327213.500-milky-way-may-have-a-huge-hidden-neighbour.html



my first thought on this was about a possible collision like we're seeing with NGC 2207 and IC 2163, in which they're just tearing each other apart.

[NYC_SKP]

1. OT: Disappointed to learn that deep space "photos" are hand colored...

It burst my bubble to learn that the radiation creating the images is not in the visible light spectrum, the colors are "artistically" added and do not represent anything like what you would "see" if you actually could view these distant phenomena.

[Soylent Brice]

3. like this:

Taurus-Littrow - Hubble Image 19 October 2005

still amazing and beautiful.

[NYC_SKP]

23. Very cool. Thanks, nt.

[loudsue]

27. Looks like galactic intestines.

:freak: Intestines are good.

[csziggy]

17. Not true - they are not "true color" but the colors are "assembled" to enhance the image

And add to the ability to interpret the image.

Zolt Levay of the Space Telescope Science Institute produces images from the Hubble Space Telescope. For the prepared Hubble images, Levay prefers the term "representative color."

"The colors in Hubble images are neither 'true' colors nor 'false' colors, but usually are representative of the physical processes underlying the subjects of the images," he said. "They are a way to represent in a single image as much information as possible that's available in the data."

True color would be an attempt to reproduce visually accurate color. False color, on the other hand, is an arbitrary selection of colors to represent some characteristic in the image, such as chemical composition, velocity, or distance. Additionally, by definition, any infrared or ultraviolet image would need to be represented with "false color" since those wavelengths are invisible to humans.

The cameras on Hubble and MER do not take color pictures, however. Color images from both spacecraft are assembled from separate black & white images taken through color filters. For one image, the spacecraft have to take three pictures, usually through a red, a green, and a blue filter and then each of those photos gets downlinked to Earth. They are then combined with software into a color image. This happens automatically inside off-the-shelf color cameras that we use here on Earth. But the MER Pancams have 8 different color filters while Hubble has almost 40, ranging from ultraviolet ("bluer" than our eyes can see,) through the visible spectrum, to infrared ("redder" than what is visible to humans.) This gives the imaging teams infinitely more flexibility and sometimes, artistic license. Depending on which filters are used, the color can be closer or farther from "reality."

In the case of the Hubble, Levay explained, the images are further adjusted to boost contrast and tweak colors and brightness to emphasize certain features of the image or to make a more pleasing picture.

http://www.universetoday.com/2007/10/01/true-or-false-color-the-art-of-extraterrestrial-photography/

[NYC_SKP]

22. Thanks for finding the link I couldn't find. Note use of term, "artistic license".

I'm glad you found and posted the link.

My only point is that most people, arguably, think these are real colors one would see if in space.

Nothing could be further from the truth.

NYC_SKP

[HiFructosePronSyrup]

28. Um, I think you're exaggerating.

Most people would think that color photographs they take with their cameras are pretty close to real life, and it's the same process with the Hubble. Even though "artistic license" is taken with the guy who develops your photos at the photomart. Or the software that removes red-eye, etc.

[csziggy]

31. I think people who educate themeselves are pretty aware Hubble pics are not "real"

But then there are the huge numbers of ignorant Americans who don't have a clue.

Many people I "know" online do a lot of post-imaging work with PhotoShop or other photo editing software to "enhance" their pictures and they are very aware of what is done with space photography. In fact, one worked on the earliest digital cameras used at NASA and has incredible photos he has taken of the space program and other subjects. (http://ctein.com/) He raised my awareness of the subject years ago in another online forum.

[Hugabear]

2. Cue up a cheesy television disaster flick

Here's what you need:

- Visionary scientist considered a crackpot by his peers, with estranged wife and child
- Some major city gets destroyed, and aurora borealis seen world-wide
- Visionary scientist develops plan to save Earth
- President rejects plan, goes with military's plan
- Military's plan fails, puts visionary scientist's estranged wife and child in imminent danger
- Estranged wife and child escape danger
- President authorizes visionary scientist's plan, which involves nuclear weapons or some experimental technology
- Visionary scientist saves the day
- Visionary scientist reunited with estranged wife and child

[Soylent Brice]

4. add a sub-par soundtrack by a rock band and you nailed it. n/t

[Birthmark]

5. It's probably hiding due to embarrassment.

[Soylent Brice]

9. spiral arm envy?

[Lance_Boyle]

6. Isn't it true that galactic collisions are not necessary catastophic to planets?

Or even to stars in the galaxies affected? Most of a galaxy is empty space. When they collide, mostly empty space "collides" with empty space. Given the distribution of matter in a galaxy, the odds of stars hitting each other is slim. Planets? Way slimmer.

[Soylent Brice]

8. define catastrophic.

could potentially knock planetary orbits out of whack. imagine the earth orbiting just a few miles closer or further from the sun. it's the difference between a frozen earth, and a scorched earth.

[AngryAmish]

20. The year 1994:

From out of space comes a runaway
planet, hurtling between the Earth and the Moon,
unleashing cosmic destruction. Man's civilization is
cast in ruin.

Two thousand years later, Earth is reborn...

A strange new world rises from the old: a world of
savagery, super science, and sorcery. But one man
bursts his bonds to fight for justice! With his companions
Ookla the Mok and Princess Ariel, he pits his strength,
his courage, and his fabulous Sunsword against the
forces of evil.

He is Thundarr, the Barbarian!

[Lance_Boyle]

29. awesome!

I have to admit I've sneaked a couple of Thundarr episodes on Boomerang. Fine line between camp and crap. And a damn shame how not even 5 years later, they gave him a new sword and changed his name to He-Man (OK, OK - Adam. Didn't mean to blow the guy's deep cover).

[Swede]

11. The stars are so far apart,actual collisions would be rare.

Stars are light years apart. Gravitational tidewaves would probably not be noticeable at the solar system level.

[Soylent Brice]

13. stars do still get caught up in each others orbits like binary stars

RXJ 0529.4+0041 for example.

whould that not have an effect in the event one came close enough?

[Swede]

19. I think stars from the same galaxies that collide can become binary

but stars from different galaxies that collide,the relative velocities would probably be cause some fireworks.

[Soylent Brice]

33. ooooh, pretty!!

[sofa king]

37. Here's something I didn't know

I was wondering what would happen if two degenerate matter bodies, like pulsars or neutron stars, collided as a result of two galaxies passing through one another.

It turns out that the universe is such a big place, degenerate body collisions happen all the time, but fortunately not so often in our own immediate neighborhood. The additional velocity imparted by two galaxies passing through one another is insignificant compared to the velocity of a binary degenerate system when it reaches the final stages of orbital decay. Just before they touch, they must be orbiting one another at close to the speed of light, according to our pals over at Bad Astronomy. And then you get an event horizon, and a fireworks display that's dangerous to be near--"near" meaning within a few thousand light years, apparently.

Here's an interesting example: two pulsars scheduled to come together in about 85 million years. Their orbital period is already down to 2.4 hours, and they're only about 500,000 miles apart. This particular system has done yeoman's service verifying relativity for us, and it seems to be losing energy through gravitational waves, which we all hope to actually find some day. Some speculate that the death radius for such an event can be as large as 5000 light years, if one is unfortunate enough to be caught in the headlights, so to speak. These chaps are only 2000 or so light years away.

It occurs to me that such events from the distant past might provide an explanation for some of the larger extinction events on Earth.

[Lance_Boyle]

30. at the speeds they'd be travelling, not so much

you are talking about a galaxy basically passing through another galaxy - quickly (perceived as even more quickly for the objects within the galaxies). Gravity might cause a minor change in trajectory, but probably not a "capture."

[Karmadillo]

7. It's obviously a terrorist galaxy. I say war and I say now.

nt

[Soylent Brice]

10. i for one welcome our future terrorist galaxy overlord.

or something.

lol

[jesus_of_suburbia]

12. Thanks for posting! Very interesting (I had never heard of a satellite galaxy)

So I looked it up, and of course its name explains it all.


"A satellite galaxy orbits a larger galaxy, due to gravitational attraction."

[Soylent Brice]

14. no problelem!

[SoCalDem]

15. The Snickers Galaxy?

:spank:

[RedCappedBandit]

16. rofl

[SIMPLYB1980]

25. That Galaxy better watch out for Patrick Chewing.

http://www.youtube.com/watch?v=kBF1lsZUlUI

[David Zephyr]

18. Fascinating article. Thanks for posting it.

:)

[progressoid]

21. perturbations??

I've been having perturbations for about a decade now.

[Peace Patriot]

24. I think this is just a speculation, to explain other findings--based on a simulation.

We are still pretty clueless about "dark matter" and a whole lot else. Could be a galaxy "hidden from view." Could be something else. This is a good way to look for discoveries (using simulations). But it is not a discovery yet. Intriguing, though--and I didn't know about these anomalies at the edges of the Milky Way.

I don't understand what holds galaxies together--and in the particular pattern of shapes they fall into, and in motion. Gravity, they say. Well, what's that? Matter "falls" toward matter, yet the whole--all of the galaxies--are galloping away from each other at increasing speed. It doesn't make sense.

We have much such incredible strides in understanding all this--when I was a kid, we had only just learned that there are other galaxies!--yet we are just grazing the surface.

I'll be interested to follow this research, and see if it leads to the discovery of an unseen neighbor galaxy, or creates some other path of research. I want to know what organizes matter into particular shapes, in motion, and what is the relationship between the objects and patterns that we humans are able to perceive, and the actual physical (and psychical?) laws of the universe? We are finally there, at changing the nature of what we see, when we look at it--by looking at it--at the subatomic level. Does that same phenomenon, of the interposition of us as observers, apply on a cosmic level? Is the universe changing because we see it? Seeing it certainly changes us.

[redqueen]

32. Of course it is... that's how theories get started...

and it's also what drives exploration and research.

[Taverner]

26. Of course we know there's an "Earth II" in there, with everyone wearing goatees

[Soylent Brice]

34. why do i find it alarming that they had better

fake ear technology way back when than they did fake goatees...?

[RedCloud]

35. So does Andromeda kill us sooner or later because of this?

Collision course of two galaxies. No ETs getting off their duffs to do anything about it either!

[Soylent Brice]

36. if anything, all other intelligent lifeforms are

cheering on our demise.