Stream of stars in Andromeda satellite galaxy shows cosmic collision

Feb 23, 2014
This diagram shows the dwarf galaxy Andromeda II with the stars belonging to the stream marked in blue. Their movement show that Andromeda II is a merger of two dwarf galaxies. Credit: Nicola C. Amorisco, N. Ho and M. Geha

The Andromeda Galaxy is surrounded by a swarm of small satellite galaxies. Researchers from the Niels Bohr Institute, among others, have detected a stream of stars in one of the Andromeda Galaxy's outer satellite galaxies, a dwarf galaxy called Andromeda II. The movement of the stars tells us that what we are observing is the remnant of a merger between two dwarf galaxies. Mergers between galaxies of such low mass has not been observed before. The results are published in the scientific journal, Nature.

The galaxies in the early universe started off small and the theory of the astronomers is that the baby galaxies gradually grew larger and more massive by constantly colliding with neighbouring galaxies to form new, larger galaxies. Large, massive galaxies constantly attract smaller galaxies due to gravity and they eventually merge together and grow even larger.

But not all of the are being 'eaten' by the large galaxies. Some of them remain in an orbit around the large galaxy. The largest galaxy in our cosmic neighbourhood is the Andromeda Galaxy, which is about 2.3 million light years away. Like our own galaxy, the Milky Way, Andromeda is a large spiral galaxy.

Swarm of small galaxies

Andromeda is surrounded by a swarm of small galaxies – astronomers have counted more than 20. They have names like Andromeda I, II, III, IV...etc. Researchers from the Dark Cosmology Centre at the Niels Bohr Institute, among others, have analysed measurements of the stars in the Andromeda II and made a surprising discovery.

Stream of stars in Andromeda satellite galaxy shows cosmic collision
The Andromeda Galaxy is a large spiral galaxy like our galaxy, the Milky Way. It is located about 2.3 million light years away and can be seen with the naked eye. The satellite galaxy Andromeda II is located in a distant orbit approximately 600,000 light years from the center of the great Andromeda Galaxy. Credit: NASA

"Stars in a dwarf galaxy often move around at random, but this is not exactly the case for Andromeda II. In particular we could see that a stream of stars is moving around differently than the rest in a very coherent way. These stars are situated in an almost complete ring and are rotating around the centre of the galaxy," explains astrophysicist Nicola C. Amorisco, Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen.

Cosmic collisions

The dwarf galaxy Andromeda II is very small – less than one percent of the Milky Way. The rotating stream of stars in the galaxy is entirely made up of old and from their properties, researchers can draw conclusions about this dramatic cosmic event.

"What we are seeing is the remains of a collision between two dwarf galaxies, which had a dramatic effect on the dynamics of the remnant," says Nicola C. Amorisco.

He explains that mergers between such small galaxies are expected during the galaxy formation process, but are rare at present times and had hitherto not been seen. Andromeda II is the least massive known example of merging of galaxies so far and illustrates the scale-free character og the formation og down to the lowest galactic mass scales.

Explore further: Universe's early galaxies grew massive through collisions

More information: The remnant of a merger between two dwarf galaxies in Andromeda II, DOI: 10.1038/nature12995

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HannesAlfven
1.2 / 5 (10) Feb 23, 2014
Re: The dwarf galaxy Andromeda II is very small – less than one percent of the Milky Way. The rotating stream of stars in the galaxy is entirely made up of old stars and from their properties, researchers can draw conclusions about this dramatic cosmic event … "What we are seeing is the remains of a collision between two dwarf galaxies, which had a dramatic effect on the dynamics of the remnant," says Nicola C. Amorisco."

As has been previously stated, astrophysicists would be wise to learn of the phenomenon of Marklund Convection, for it offers an alternative plasma-based explanation for why elemental abundances appear to vaguely sort into concentric rings. To my knowledge, the only place where this laboratory process is discussed is IEEE's Transactions on Plasma Science -- which presents a problem, for as Tim Thompson has suggested, astrophysicists are in a general sense probably not even aware that IEEE publishes on issues related to astrophysics.
Captain Stumpy
5 / 5 (9) Feb 23, 2014
astrophysicists would be wise to learn of the phenomenon

@Alfven
personal conjecture
there is plenty of evidence to support that modern astrophysicist understand plasma
see:
http://phys.org/n...vae.html
http://iopscience...1_41.pdf &
http://phys.org/n...ack.html &
http://arxiv.org/.../0512549 &
http://phys.org/n...ggs.html &
http://phys.org/n...ank.html
http://phys.org/n...end.html

marklund convection is an archaic term as pointed out in the first link by Tim Thompson
Also:
astrophysicists dont visit IEEE because that would be like asking a Firefighter to visit the world plumbing institute to learn about water
IEEE is NOT the only game in town, and elec. Engineers (EE) do NOT take astrophysical effects into consideration when speculating about plasma, whereas astrophysicists DO
CaptainCosmic
5 / 5 (9) Feb 23, 2014
Captain S.: While I commend your attempt to reason with this obvious troll, I question why you engage him (her,them) and his sockpuppets. His ( I assume he's a dude since gals are rarely so bull-headed) "theories" are actually the kind of pseudo-babble that the posting guidelines warn will get someone banned. Why is this abusive, ignorant, spammer bastard still allowed to post? Even I have resorted to an off-topic post at this point, to suggest we down-vote and report (if that even works). As for the troll: I have no intention of engaging him. Good work on exposition Capt. Stumpy...at least you have a working neo-cortex.

Captain Cosmic: cosmologist
Whydening Gyre
2 / 5 (4) Feb 23, 2014
Cap'n. Love ya, but while understanding and respecting your forward looking view;
marklund convection is an archaic term as pointed out in the first link by Tim Thompson

Santayana said (paraphrasing) - Those who neglect history are often bound to repeat it.
astrophysicists dont visit IEEE because that would be like asking a Firefighter to visit the world plumbing institute to learn about water

Why wouldn't a fire fighter want to know the basics about what makes his job possible?
IEEE is NOT the only game in town, and elec. Engineers (EE) do NOT take astrophysical effects into consideration when speculating about plasma, whereas astrophysicists DO

EEs know electricity, why would an astro physicist NOT take that into consideration when DOing their speculation?
One peace/love
philw1776
5 / 5 (2) Feb 23, 2014
Galaxies indulge in dwarf tossing? Who knew that such un-PC events were astrophysical?
Captain Stumpy
5 / 5 (3) Feb 24, 2014
Those who neglect history are often bound to repeat it

@Whydening Gyre
check out his comments in the thread. It will enlighten you about the issue above, it really is not an issue of forgetting the history. :-)
Why wouldn't a fire fighter want to know

actually, in my 6 month academy there was 30 days devoted to plumbing/hydraulics, but we didnt need a plumber for this, just hydraulics/fluid dynamics and basic physics courses
and the following 2 yrs apprenticeship (average time given to complete further training and experience) it is required to know plumbing, but mostly the specifications etc for building codes/inspections. But again, there was no need to be trained as a plumber when the basics were sufficient to get the point across (from friction, pressures, fluid dynamics, weight, etc).
you wouldnt call a FF to do the plumbing on your new home, just like you wouldnt call a plumber when your home caught on fire...
two different perspectives.
Captain Stumpy
5 / 5 (4) Feb 24, 2014
EEs know electricity, why would an astro physicist NOT take that into consideration when DOing their speculation?

@Whydening Gyre
they DO take it into consideration
Astrophysicists learn about plasma's, EE's DONT learn about astrophysics
that is the meat of my argument
when Alfven or CD make a claim like that, it is not only obviously false, it is meant to obfuscate and the comment is used to establish that there is something wrong today (intentionally misleading & repeated to establish the lie as truth)
first off, the comment is based upon Hannes statements more than thirty years ago
also, it is an outright LIE
check out ANY college curriculum to be an astrophysicist... or ask one, they have to learn about plasma's or Ask CaptainCosmic or Q-Star
I checked a LOT of colleges the first time I saw this statement and found that they ALL required it.
Then there is the stuff Thompson posted, proving it all crap all over again... read his posts, WG, you will learn a LOT.
Captain Stumpy
5 / 5 (7) Feb 24, 2014
While I commend your attempt to reason with this obvious troll, I question why you engage him (her,them) and his sockpuppet

@CaptainCosmic
Thank you for the compliment.
I do it for a few reasons
I come here to learn, and it helps me learn
it also helps others to spot pseudosciences (BIG reason here- my grandkids are learning too... some people are not scientifically literate enough to research and find answers)
the moderators seem to be mostly hands off... and I have time on my hands
are actually the kind of pseudo-babble that the posting guidelines warn will get someone banned

yep
and everything else you said takes TIME to work... too much time, sometimes, given the lack of moderation
I am retired... what else am I going to do when I am snowed in? :-)
Fleetfoot
5 / 5 (7) Feb 24, 2014
it also helps others to spot pseudosciences (BIG reason here- my grandkids are learning too... some people are not scientifically literate enough to research and find answers)


My reason too, thank you for that, it is appreciated.

the moderators seem to be mostly hands off


I did once get a warning for "pseudo-science" for saying that in an EM wave, the electric and magnetic field vectors are perpendicular. If the site is to be of any value, posts explaining what is valid science and what is trolling, technobabble or just clueless nonsense are essential.
CaptainCosmic
5 / 5 (5) Feb 24, 2014
Capt. S.: I too am semi-retired. Actually disabled, but the mind works as well as my speech to text engine & occasionally my hands. I see thus that you are acting as de facto moderator, a thankless job to be sure. I have noticed that the worst of the trolls always pick the 'sexy' topics like STR, GTR, QM, string theory, HEP, etc. I never see this crap in the solid state threads, or chemistry or other less 'exotic' topics. Science trolling is at its worst in Cosmology, particle physics & cutting edge ideas like string theory, quantum gravity, and black-hole dynamics. Fight the good fight my friend, you are doing God's work. I'll try to help out if I can, when I can. Capt.C.
yyz
5 / 5 (6) Feb 24, 2014
Back on the topic of And II, it should be noted that even before the current study this dwarf galaxy was considered unusual. And II is the second largest dwarf spheroidal in the Local Group and displays a peculiar surface brightness profile unique for dwarf galaxies. Rotation is about the minor axis, also a rarely observed condition of elliptical systems of any mass and a first for a dSph:

http://arxiv.org/abs/1209.2116

Previous studies have also found two stellar populations in And II. One is a centrally-concentrated, metal-rich intermediate age(~7-10 Gyr) population while the other is extended, metal-poor and old(~13 Gyr):

http://arxiv.org/abs/0705.1520

It's tempting to speculate that the proposed merger occurred around the time the intermediate age population was formed(accreted?) and future studies of And II are sure to look into this possibility. BTW, a preprint of current paper in Nature is available here:

http://arxiv.org/abs/1402.5142
Captain Stumpy
5 / 5 (3) Feb 24, 2014
Back on the topic of And II,

@yyz
sorry. without the PM function I get distracted... wish we had it back. I have LOADS of questions and I am still burning my brain up researching them... would love to ask Q-Star or someone
and future studies of And II are sure to look into this possibility. BTW, a preprint of current paper in Nature is available here:

thanks for those GREAT links... they are helpful
going through them now
Tuxford
1 / 5 (4) Feb 24, 2014
"The Andromeda Galaxy is surrounded by a swarm of small satellite galaxies. "

Why? Because they are daughter galaxies ejected from deep within the parent. Or we let merger mania continue unabated in the fanciful minds of modern astronomers. Merging satellites? Maybe. But where are all the baby galaxies in intergalactic space left over from the fabled beginning??? They all managed to find a home orbiting some other galaxy??? Want to buy a bridge?
Whydening Gyre
5 / 5 (3) Feb 24, 2014
I am retired... what else am I going to do when I am snowed in? :-)

Drink more coffee? take a nap? read? wild woohoo with wife? limited only by your imagination, m'friend...:-).
LeoVuyk
1 / 5 (3) Feb 25, 2014
In Quantum FFF theory, Dwarf Galaxis are originated in between two or more so called Galaxy Anchor black holes. However, dwarfs seem to be not stable due to the strang attraction forces of thes black hole.
They can collide and even disrupt into star streams called "Polar galaxy rings" of stars.'
see:
image 145 of: http://www.flickr...etails=1
GSwift7
5 / 5 (3) Feb 25, 2014
Back on the topic of And II, it should be noted that even before the current study this dwarf galaxy was considered unusual


It makes me wonder how unusual it is, since the total number of dwarf galaxies we are able to observe is limited by proximity. You need to be able to pick out fairly high levels of detail in order to know details of composition and motion within the galaxy. At greater distances we struggle to go beyond the bulk properties of the dwarf galaxy as a whole (at least for now, but DEIMOS on Keck II is very state of the art, so don't expect much better in the near future). Not only can Keck get unmatched detail, the DEIMOS instrument can get high resolution spectra on many objects at the same time, which makes this observation extremely difficult to duplicate on any other instrument.
cantdrive85
1 / 5 (4) Feb 25, 2014
Hal Arp saw these dwarf galaxies as childrens of the larger galaxies they orbit.
http://www.halton..._pacific
yyz
5 / 5 (4) Feb 25, 2014
"Not only can Keck get unmatched detail, the DEIMOS instrument can get high resolution spectra on many objects at the same time, which makes this observation extremely difficult to duplicate on any other instrument."

It's probably more accurate to say that hi-res studies of dwarf galaxies in the Local Group(spectra/kinematics) are best conducted with 8-10m class telescopes. All 8-10m class 'scopes use state-of-the-art instrumentation, not just Keck(see my second link above). It's true that study of individual stars in dwarf galaxies are limited to Local Group systems and even JWST or the new crop of giant terrestrial 'scopes(EELT, GMT etc.) won't be able to study individual stars in dwarf galaxies in, say, the Perseus Galaxy Cluster(Abell 426).

@cantdrive, with the passing of Arp it seems like observational astronomers investigating alternative/unsupported astrophysics are a dying breed (Carlqvist and Verschuur are both retired, as is plasma physicist Peratt).
GSwift7
5 / 5 (2) Feb 26, 2014
It's probably more accurate to say


That's true.

I was just trying to point out, to people who may not know, that the type of equipment needed for this work is rare. There are only about a dozen comparable instruments ever made, and it could be argued that some of those dozen don't really have the horsepower of Keck, especially the 8 meter class with one-piece mirrors. GTC has a larger mirror, but less light gathering due to the design. Keck really is the best of the best, and resolving individual stars in another galaxy is not trivial.

Are there any other multi-object spectrometers that can track as many objects as DEIMOS? I doubt the above work could have been done with only 1 or 2 hundred stars sampled by the spectrometer, which is about the best Subaru can do.

Also, about half of the 8 meter and above telescopes are in the southern hemisphere, and Andromeda is apx 40 degrees north.
Tim Thompson
5 / 5 (3) Feb 28, 2014
As has been previously stated, astrophysicists would be wise to learn of the phenomenon of Marklund Convection, for it offers an alternative plasma-based explanation for why elemental abundances appear to vaguely sort into concentric rings.

Hah! You can't even get your own pseudoscience pseudoscientifically correct!! The article here is talking about the distribution of individual stars, whereas "Marklund convection" deals with the diffusion (not convection) of individual atomic nuclei in a magnetized plasma. Even you can't come up with a way for "Marklund convection" to move a whole star.
cantdrive85
1 / 5 (2) Feb 28, 2014
As has been previously stated, astrophysicists would be wise to learn of the phenomenon of Marklund Convection, for it offers an alternative plasma-based explanation for why elemental abundances appear to vaguely sort into concentric rings.

Hah! You can't even get your own pseudoscience pseudoscientifically correct!! The article here is talking about the distribution of individual stars, whereas "Marklund convection" deals with the diffusion (not convection) of individual atomic nuclei in a magnetized plasma. Even you can't come up with a way for "Marklund convection" to move a whole star.

LOL! Stumped by the scalability of plasma processes?
Captain Stumpy
5 / 5 (3) Mar 01, 2014
LOL! Stumped by the scalability of plasma processes?

@cd
apparently YOU are... is this "scalability" somehow related to how Saturn/etc and the Sun changed places? is it related to how the moon's craters were formed by plasma discharges? Is it related to the Grand Canyon formation?

something that is powerful enough to do what you are saying should also have other observable/physical effects.
for instance, with regard to the grand canyon/moon crater formations: given the discharge of power to create the formation, there would be evidence created and still measurable/visible today, such as the creation of secondary evidence through heat/electric/other discharge/formations processes.
therefore observational evidence of one would immediately provide a pattern that was distinguishable and would allow us to find the physical/observational evidence of the other, as I told you before.

this should be easy enough for you... give your proof
Tim Thompson
5 / 5 (3) Mar 06, 2014
LOL! Stumped by the scalability of plasma processes?

Plasma processes are neither more nor less scalable than any other physical processes. In all cases scalability is allowed only when the energy permits. When dealing with gases made of individual ions & charged particles that are relatively small, processes can and do scale over a very large range of distances. But the energy is not there to move a star with any electromagnetic field, so scalability is not relevant to this discussion.

Your problem is that you are monumentally ignorant of all things physics, especially plasmas, so all you can do is repeat buzzwords as if you understood them & rules of thumb as if they were laws of physics. But you are not fooling anybody with your false bravado.
Maggnus
5 / 5 (2) Mar 07, 2014
Capt. S.: I too am semi-retired. Actually disabled, but the mind works as well as my speech to text engine & occasionally my hands. I see thus that you are acting as de facto moderator, a thankless job to be sure. I have noticed that the worst of the trolls always pick the 'sexy' topics like STR, GTR, QM, string theory, HEP, etc. I never see this crap in the solid state threads, or chemistry or other less 'exotic' topics. Science trolling is at its worst in Cosmology, particle physics & cutting edge ideas like string theory, quantum gravity, and black-hole dynamics. Fight the good fight my friend, you are doing God's work. I'll try to help out if I can, when I can. Capt.C.


Judging by what you've said here, your voice is welcomed and I extend you welcome as well!
Maggnus
5 / 5 (3) Mar 07, 2014
Hal Arp saw these dwarf galaxies as childrens of the larger galaxies they orbit.
http://www.halton..._pacific
Arp saw a lot of things, some of which were right, some of which are wrong. You've posted to an example of the latter.

BTW, how do you square his concepts of tired light with your gurus' ideas of Birkland currents?

Don't bother to answer that, it's rhetorical. And the fact that you are even able to confuse the preachings of your own high priests doesn't bode well for any answer you may give!