APOD: M64: The Black Eye Galaxy (2013 Apr 04)

[APOD Robot]

M64: The Black Eye Galaxy

Explanation: This beautiful, bright, spiral galaxy is Messier 64, often called the Black Eye Galaxy or the Sleeping Beauty Galaxy for its heavy-lidded appearance in telescopic views. M64 is about 17 million light-years distant in the otherwise well-groomed northern constellation Coma Berenices. In fact, the Red Eye Galaxy might also be an appropriate moniker in this colorful composition of narrow and wideband images. The enormous dust clouds obscuring the near-side of M64's central region are laced with the telltale reddish glow of hydrogen associated with star forming regions. But they are not this galaxy's only peculiar feature. Observations show that M64 is actually composed of two concentric, counter-rotating systems of stars, one in the inner 3,000 light-years and another extending to about 40,000 light-years and rotating in the opposite direction. The dusty eye and bizarre rotation is likely the result of a billion year old merger of two different galaxies.

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[Beyond]

Black eye... Red eye... Just what is this galaxy getting into when we're not looking?

[Moonlady]

Black eye... Red eye... Just what is this galaxy getting into when we're not looking?

It is watching you, my Beyonderland brother!

[Beyond]

Ah, that's why it's going in two directions at the same time!

[Boomer12k]

Curious place....two counter-rotating systems of stars. Fascinating...I wonder if, like the core of a planet, if that causes any dynamism. I wonder if gravity will eventually balance out between the two, and it would slow down the least massive system, and start rotating in unison. It must still be in a "mixing" phase. Like stirring a drink in one direction, and then changing the direction of the spoon.

I wonder what the dark matter is doing in the galaxy...

:---[===] *

[Ann]

This is a very fine picture of a most interesting galaxy. The picture underscores and to some degree enhances the color differences between the different parts of the galaxy. Star formation in M64 is confined to a very small dust disk close to the center of the galaxy. In the rest of the galaxy, star formation has long ago ceased, and the ripples of star formation, the galactic spiral arms, are slowly dying out like the ripples in a calm lake, when there are no more disturbances to upset the liquid peace.

I said that the color differences of the different parts of the galaxy have been enhanced. We have every reason to believe that the non-starforming disk of M64 is made up of a mixture of old and intermediate stars, and that its overall color is slightly yellowish.

Personally I think it is very interesting to compare M64 with at least two other galaxies. A near-twin of M64 is M90. Just like M64, M90 has a rather small inner dust disk with some star formation and a rather large outer disk where the "dead" spiral arms are slowly merging with the underlying smooth thick and thin disks of the galaxy. It is probable that the overall colors of M90 are slightly bluer than the colors of M64, and that the non-starforming disk of M90 contains a somewhat higher percentage of intermediate stars than the disk of M64. The B-V index of M64 is +0.840, whereas the B-V index of M90 is +0.720.

Another galaxy that is somewhat similar to M64 is the large but mostly "dead" spiral galaxy NGC 4921 in the Coma cluster of galaxies, which you can see here and here. The filters used for producing this image were clearly not aimed at bringing out subtle color differences across the face of NGC 4921. It is possible, indeed probable, that the inner bulge would look noticeably yellower than the disk of the galaxy if the picture had been taken through RGB filters. What is clear, however, is that NGC 4921 has a weak dust ring (not a dust disk of any kind) which contains clusters of young stars. Whether or not there is any ongoing star formation or any pink emission nebulae in this dust ring is anybody's guess. We can see, however, that the disk has a "dying spiral pattern". The spiral arms are disappearing and merging into the underlying think and thick disks of the galaxy. Colorwise, unsurprisingly, NGC 4921 is redder than both M64 and M90, with a B-V index of +0.870.

M64, M90 and NGC 4921 are three perfect examples of spiral galaxies where star formation has disappeared except from a small inner region close to the center of the galaxy, and where the spiral arms of the outer disk are dying out like the disappearing ripples of a pond, when you stop throwing pebbles into it.

We are actually watching entropy in action.

Ann

[orin stepanek]

Looks like a lack of dust lanes in the outer regions! If it is a merger of two; i wonder if one of the two was an eliptical? Just my thoughts on this!

[neufer]

M64: The Black Eye Galaxy

Explanation: Observations show that M64 is actually composed of two concentric, counter-rotating systems of stars, one in the inner 3,000 light-years and another extending to about 40,000 light-years and rotating in the opposite direction.

Where does anyone state that "M64 is actually composed of two concentric, counter-rotating systems of stars."

It is rather the gas in the center that rotating backwards (i.e., counterclockwise).

At first glance, M64 appears to be a fairly normal pinwheel-shaped spiral galaxy. As in the majority of galaxies, all of the stars in M64 are rotating in the same direction, clockwise as seen in the Hubble image. However, the interstellar gas in the outer regions of M64 rotates in the opposite direction from the gas and stars in the inner regions.... What caused the backwards rotation of the gas in the center of this galaxy?

[Boomer12k]

By gosh Art, you are right...the original article says GAS, not stars...all the stars rotate in the same direction....bad write up...gives wrong impressions....

Thanks for pointing in the right direction.

:---[===] *

[Guest]

Where does anyone state that "M64 is actually composed of two concentric, counter-rotating systems of stars."

It is rather the gas in the center that rotating backwards (i.e., counterclockwise).

[quote=" http://heritage.stsci.edu/2004/04/supplemental.html"]

Maybe it should be renamed The Egg on Face Galaxy.

[owlice]

Guest, rudeness is against the rules; kindly read them before posting again. Thank you.

Thanks, Art; I've let the APOD editor know.

[CuriousNewbie]

I was just wondering, has anybody done a study on which direction each galaxy rotates? On earth water will drain down a sink clockwise or counterclockwise depending on which side of the planet you are on, so I was wondering if there was any pattern to the directions galaxies are heading and the average rotation. Would this be helpful in finding large concentrations of dark matter?

[neufer]

I was just wondering, has anybody done a study on which direction each galaxy rotates? On earth water will drain down a sink clockwise or counterclockwise depending on which side of the planet you are on, so I was wondering if there was any pattern to the directions galaxies are heading and the average rotation. Would this be helpful in finding large concentrations of dark matter?

Go to: http://asterisk.apod.com/viewtopic.php?f=8&t=30960

[Chris Peterson]

I was just wondering, has anybody done a study on which direction each galaxy rotates? On earth water will drain down a sink clockwise or counterclockwise depending on which side of the planet you are on, so I was wondering if there was any pattern to the directions galaxies are heading and the average rotation. Would this be helpful in finding large concentrations of dark matter? :?:

If you are referring to the relationship between the direction of stellar rotation and the curvature of spiral arms, all spiral galaxies rotate in the same direction. But if you are comparing different galaxies, they all have angular momentum vectors pointing in different directions. Of course, as we see them, "direction" is simply a matter of which side we're seeing them from.

There is evidence that galaxies that define certain parts of the large scale structure of the Universe (such as along bubble walls) may have a slight correlation of their rotations- not entirely surprising, as these probably formed together to some degree.

[Chris Peterson]

By gosh Art, you are right...the original article says GAS, not stars...all the stars rotate in the same direction....bad write up...gives wrong impressions....

However, there's nothing physically impossible about a galaxy with counter-rotating stars, and such a system could be stable for a very long time. It would simply require just the right sort of collision between two spiral systems. The typical result of such a collision is an elliptical galaxy, which is one that has no strongly favored axis or direction of rotation but where every star is randomly inclined.

[Ron-Astro Pharmacist]

Say the two galaxies had rotating black holes at their center. I suspect the rotation for each would be in the same orientation as their respective galaxies. Should an interaction between the two black holes occur, I am curious if the black holes opposite spin would have peculiar properties:?:

I have no idea how we could detect rotating black holes let alone if they are of opposing direction but the thought crossed my mind knowing some think most galaxies have black holes at their centers.

[stephen63]

Say the two galaxies had rotating black holes at their center. I suspect the rotation for each would be in the same orientation as their respective galaxies. Should an interaction between the two black holes occur, I am curious if the black holes opposite spin would have peculiar properties:?:

I have no idea how we could detect rotating black holes let alone if they are of opposing direction but the thought crossed my mind knowing some think most galaxies have black holes at their centers.

Here is a link to an explanation of how to detect a rotating black hole. Good stuff!
http://www.slate.com/blogs/bad_astronom ... ating.html

[neufer]

there's nothing physically impossible about a galaxy with counter-rotating stars, and such a system could be stable for a very long time. It would simply require just the right sort of collision between two spiral systems. The typical result of such a collision is an elliptical galaxy, which is one that has no strongly favored axis or direction of rotation but where every star is randomly inclined.

"It's theoretically possible in the same way as a manned mission to Mars is theoretically possible." - That's how English fish expert Dr. Alfred Jones (a.k.a., Ewan McGregor/ Obi-Wan Kenobi) responds to the idea of transplanting 10,000 Scottish salmon to the arid country of Yemen on the southern tip of the Arabian Peninsula in Salmon Fishing in the Yemen.

[Chris Peterson]

Say the two galaxies had rotating black holes at their center. I suspect the rotation for each would be in the same orientation as their respective galaxies. Should an interaction between the two black holes occur, I am curious if the black holes opposite spin would have peculiar properties:?:

The spin of black holes has no significant physical effect except very close to their event horizons. Until just before they collide and merge, the interaction of black holes is very simple- just classical two-body gravitational interaction (which doesn't involve spin at all). For all practical purposes, a pair of black holes orbiting each other can be treated as point-source masses, with mass being the only relevant physical property.

[Ron-Astro Pharmacist]

Thanks for your replies. I always appreciate all of your time and knowledge. I lose track of the notion that a black hole is a point-like object. A collision of two oppositely spinning points seems to me a more natural event. (Don't ask me why)

The matter in the accretion discs does still seem to be a separate and different issue. Would such a collision essentially be a very large and natural particle collider should that part its system begin an interaction?

[Chris Peterson]

The matter in the accretion discs does still seem to be a separate and different issue. Would such a collision essentially be a very large and natural particle collider should that part its system begin an interaction? :D

There was just a report that described the particles in an accretion disc approaching the speed of light near the event horizon. The merger of two black holes with accretion discs must surely be a dynamically complex and extraordinarily energetic event.

[ErnieM]

M64: The Black Eye Galaxy

Explanation: Observations show that M64 is actually composed of two concentric, counter-rotating systems of stars, one in the inner 3,000 light-years and another extending to about 40,000 light-years and rotating in the opposite direction.

Where does anyone state that "M64 is actually composed of two concentric, counter-rotating systems of stars."

It is rather the gas in the center that rotating backwards (i.e., counterclockwise).

At first glance, M64 appears to be a fairly normal pinwheel-shaped spiral galaxy. As in the majority of galaxies, all of the stars in M64 are rotating in the same direction, clockwise as seen in the Hubble image. However, the interstellar gas in the outer regions of M64 rotates in the opposite direction from the gas and stars in the inner regions.... What caused the backwards rotation of the gas in the center of this galaxy?

NGC3626 http://astrosun2.astro.cornell.edu/academics/courses/astro233/demo/n3626.htm See Herchel Measures Dark Matter for Star Forming Galaxies for possible explanation of gas-rich dwarf galaxy http://asterisk.apod.com/viewtopic.php?f=31&t=22929

---

Nature 375, 661 - 663 (22 June 1995) says:

IN some galaxies that have little gas remaining from the epoch of galaxy formation, the gas that is present rotates in the opposite sense to the stars1–4. It is thought that this counter-rotating gas may result from the capture by a massive early-type galaxy of a gas-rich dwarf galaxy that was orbiting in the opposite sense to the main galaxy’s rotation; but as there are few examples of galaxies with counter-rotating gas, we have little information about the details of this process. Here we present optical spectra of the spiral5,6 galaxy NGC3626, which clearly show the presence of counter-rotating ionized gas; combining these results with preexisting atomic hydrogen data7 leads to an estimate of 109 M⊙ for the mass of the gas. Spiral galaxies generally contain substantial amounts of gas left over from the formation epoch, which would be co-rotating with the stars; this gas should interact strongly with the counter-rotating gas on a relatively short timescale, causing it to fall towards the centre of the galaxy. We therefore propose that the counter-rotating gas in NGC3626 has been captured recently; the merger process is just beginning.

[Kopernik]

My first time posting – Read some of your comments and am impressed with the depth of examination of the subjects. Still, am not confident that any of you will be sufficiently tolerant of contrarian scientific concepts to allow me to post again.

M64 is an intriguing example of a hypothesis I describe as ‘flip-flop’ or tumbled galactic nucleus.
First scientific heresy: The claim here is that the sudden, uneven loading of a black hole can cause that spinning body to wobble, e.g., our own galaxy and M31, and can in extreme cases flip or turn over, and appear to spin in a direction opposite to its earlier spin. In the example of a wobble, the extra mass forms a node on the total nuclear mass. The propagating (mostly) gravitational waves through the galaxy cause the outer most stars to form a wavy edge. In the latter case the impacting (black hole) mass is large enough to force the resulting entity to roll over. Development of the galaxy from this point on is influenced by this new rotational direction.
Second scientific heresy: Directly and indirectly the galactic nucleus, with a number of emanations (not described here), influences the star pattern (formation) of that galaxy.
Third heresy: Black holes do not or cannot completely merge, one with another. Particularly those that have spin. They may form a close, intimate association, but not a singular union. Perhaps only light seconds apart , they may exhibit other properties in common.
Thus, a mature galaxy’s nucleus may be composed thousands, perhaps billions, of black holes of all masses and spin. The changing configuration, or relationship between units, of the black hole content of the nucleus over time affects the pattern of new star formation. Every new addition of mass alters a bit the stability of the earlier association of black holes forming the nucleus. E.g., when the overall orbital pattern of the black holes to each other is random not fixed, star formation will be look random or peculiar. With additional mass the black holes will take up more or less fixed orbits. The new star pattern becomes elliptical or spherical. The emanations, such as various radiation, gravity and magnetic waves, become more orderly. With the acquisition of even more black holes, along with their mass and angular momentum, the nucleus is forced for the sake of harmony to assume an overall flattened bar shape. (There are always rogue, non conformist black holes in the environment; can cause redirection of nuclear energies.) The emanations find it convenient to travel down the bar and to discharge from the tips. Mostly. The width of the nuclear bar (our view) depends upon the number of black hole masses that lay outside that prominent line of black holes that together turn slowly like the propeller of a plane. It is the discharged energy from the tips that triggers new star formation. The galaxy now looks spiral. (The number of rogue holes determines the width of the bar, or its complete absence.) [I have written extensively on this subject.]
Getting back to M64 - This may a case of the spiraling nucleus being suddenly flipped over; it continued to produce new stars with the spiral patter, but in a different direction.
For an example if a 90 degree flip see NGC 4650A. The Hubble Heritage Project's picture.
Thanks for letting me post this one time. Too bad I won’t get to describe ‘Mitosis of Galactic Nuclei’.
K2

[Chris Peterson]

My first time posting – Read some of your comments and am impressed with the depth of examination of the subjects. Still, am not confident that any of you will be sufficiently tolerant of contrarian scientific concepts to allow me to post again.

This forum is not tolerant of "contrarian scientific concepts" at all. If you can't support your ideas with material from the mainstream literature, you would be better of discussing them in another place. This forum is for discussing the accepted science describing phenomena, and to a certain extent the new or speculative ideas emerging from scientists or institutions with a history of producing important new interpretations.