APOD: NGC 1055 Close-up (2017 Nov 09)

Comments and questions about the APOD on the main view screen.
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APOD: NGC 1055 Close-up (2017 Nov 09)

Postby APOD Robot » Thu Nov 09, 2017 5:06 am

Image NGC 1055 Close-up

Explanation: Big, beautiful spiral galaxy NGC 1055 is a dominant member of a small galaxy group a mere 60 million light-years away toward the aquatically intimidating constellation Cetus. Seen edge-on, the island universe spans over 100,000 light-years, a little larger than our own Milky Way. The colorful stars in this cosmic close-up of NGC 1055 are in the foreground, well within the Milky Way. But the telltale pinkish star forming regions are scattered through winding dust lanes along the distant galaxy's thin disk. With a smattering of even more distant background galaxies, the deep image also reveals a boxy halo that extends far above and below the central bluge and disk of NGC 1055. The halo itself is laced with faint, narrow structures, and could represent the mixed and spread out debris from a satellite galaxy disrupted by the larger spiral some 10 billion years ago.

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby Ann » Thu Nov 09, 2017 5:56 am

That is a very fine and interesting picture! I particularly like the boxy halo, and I have to wonder if that is a signature of a (long?) bar.

Ann
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Alex675

Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby Alex675 » Thu Nov 09, 2017 8:47 am

There is a strange-shaped backgound galaxy, top right of the image.

MottyGlix

Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby MottyGlix » Thu Nov 09, 2017 10:22 am

"far above and below the central 'bluge'"?

NCTom

Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby NCTom » Thu Nov 09, 2017 12:55 pm

There seems to be a distortion slightly above the disk on its far left side and a more prominent distortion below its right side. Might these also be the result of an interaction with another galaxy? Beautiful image. Like Alex675 I find the galaxy with its halos in the upper right side interesting. Does a more detailed image of it exist and how would we find it?

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby bls0326 » Thu Nov 09, 2017 1:37 pm

wonderful picture.

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby Saeed Khan » Thu Nov 09, 2017 1:38 pm

Recently I heard about a theory that our Solar System not only rotates around the Milky Way Galaxy, it also moves up and down while doing so. Whenever it passes through the Central Disk of Dark Matter, the Dark Matter dislodges asteroids of the asteroid belts. Some of these then hit our planet, causing extinction of most species on Earth!

By looking at the image of NGC-1055, one can see a band of debris of the disrupted galaxy. May be, such debris of disrupted galaxies is also pulled up/down by the galaxy and this debris keeps oscillating up and down the plane of this galaxy. Since our Solar System is also moving up and down through the plane of Milky Way Galaxy, as it revolves around Milky Way’s center, may be it also keeps passing through such debris of other such disrupted galaxies, after few 100 million years, and asteroids in this debris keep hitting our planet once in a while.

In other words, Astronomy is extremely serious business and our very survival may depend on such knowledge. Instead of acting like two gambling sailors whose ship is sinking but they are busy fighting over few pennies, we should be busy developing technologies required to avoid any such future mishaps.

RogueRob

Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby RogueRob » Thu Nov 09, 2017 1:49 pm

Is that a blue star toward the upper left that has a faint, narrow ring?

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby neufer » Thu Nov 09, 2017 2:37 pm

RogueRob wrote:
Is that a blue star toward the upper left that has a faint, narrow ring?

:arrow: Computer-generated image of an Airy disk. The gray scale intensities have been adjusted to enhance the brightness of the outer rings of the Airy pattern.
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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby sillyworm2 » Thu Nov 09, 2017 2:41 pm

Stunning image! Nothing takes my breath away like the visual wonder of a Galaxy!

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby Chris Peterson » Thu Nov 09, 2017 2:47 pm

Saeed Khan wrote:Recently I heard about a theory that our Solar System not only rotates around the Milky Way Galaxy, it also moves up and down while doing so. Whenever it passes through the Central Disk of Dark Matter, the Dark Matter dislodges asteroids of the asteroid belts. Some of these then hit our planet, causing extinction of most species on Earth!

This hypothesis is entirely unsupported by evidence. The Solar System moves slightly upward and downward with respect to the galactic plane (which is itself not well defined), over a 30 million year period. A review of the geological record reveals no related periodicity in asteroid or comet collisions with the Earth or other planets.

Furthermore, there is no reason to think that there is a dark matter disk. Because dark matter doesn't interact with electromagnetic radiation, there is no mechanism to cause flattening of dark matter clouds. Dark matter associated with galaxies exists in the form of a halo- a big blob that the galaxy sits in, not a structured disk like we get with ordinary matter.

From the standpoint of orbital dynamics, there's no reason to think our slightly changing vertical position within the galactic disk should have any impact. The density of the regions we traverse is substantially the same from the farthest north to the farthest south we go. And given the size of our system in comparison with our distance from the center of the galaxy, tidal forces (which is what we need to disrupt the Oort cloud) are exceedingly small. Of far more impact is the occasional near encounter with a star or star cluster.
Chris

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby neufer » Thu Nov 09, 2017 5:15 pm

Chris Peterson wrote:
Saeed Khan wrote:
Recently I heard about a theory that our Solar System not only rotates around the Milky Way Galaxy, it also moves up and down while doing so. Whenever it passes through the Central Disk of Dark Matter, the Dark Matter dislodges asteroids of the asteroid belts. Some of these then hit our planet, causing extinction of most species on Earth!

This hypothesis is entirely unsupported by evidence.

    The necessary evidence, one way or the other, should be coming from Gaia:
http://www.dailygalaxy.com/my_weblog/20 ... ss-ex.html wrote:
Our Solar-System's Scary Orbit Through Milky Way's Dark Matter Disk
Daily Galaxy, May 05, 2014

<<Our Sun orbits around the Galactic center, taking approximately 250 million years to make a complete revolution. [Also] the Solar System weaves up and down, crossing the plane of the Milky Way approximately every 32 million years. This bobbing motion, which extends about 250 light years above and below the plane, is determined by the concentration of gas and stars in the disk of our Galaxy. This ordinary “baryonic” matter is concentrated within about 1000 light years of the plane. Because the density drops off in the vertical direction, there is a gravitational gradient, or tide, that may perturb the orbits of comets in the Oort cloud, causing some comets to fly into the inner Solar System and periodically raise the chances of collision with Earth. However, the problem with this idea is that the estimated galactic tide is too weak to cause many waves in the Oort cloud.

In their new study [Dark Matter as a Trigger for Periodic Comet Impacts, Lisa Randall and Matthew Reece,Phys. Rev. Lett. 112, 161301 (2014), Published April 21, 2014], Randall and Reece suggest that the galactic tide could be made stronger with a thin disk of dark matter. Dark disks are a possible outcome of dark matter physics, as the authors and their colleagues recently showed. Here, the researchers consider a specific model, in which our Galaxy hosts a dark disk with a thickness of 30 light years and a surface density of around 1 solar mass per square light year. Although one has to stretch the observational constraints to make room, their thin disk of dark matter is consistent with astronomical data on our Galaxy.

Randall and Reece’s dark disk model is not made of an ordinary type of dark matter. The most likely candidate of dark matter—known as weakly interacting massive particles (WIMPs)—is expected to form a spherical halo around the Milky Way, instead of being concentrated in the disk. This WIMP dark matter scenario has been remarkably successful in explaining the large-scale distribution of matter in the Universe. But, there is a long-standing problem on small-scales—the theory generally predicts overly dense cores in the centers of galaxies and clusters of galaxies, and it predicts a larger number of dwarf galaxy satellites around the Milky Way than are observed.

Alternatively, this small-scale conflict could be evidence of more complex physics in the dark matter sector itself. One solution is to invoke strong electromagnetic-like interactions among dark matter particles, which could lead to the emission of “dark photons”. These self-interactions can redistribute momentum through elastic scattering, thereby altering the predicted distribution of dark matter in the innermost regions of galaxies and clusters of galaxies as well as the number of dwarf galaxies in the Milky Way. Although self-interacting dark matter could resolve the tension between theory and observations at small-scales, large-scale measurements of galaxies and clusters of galaxies only allow a small fraction (less than 5%) of the dark matter to be self-interacting. Recently, Randall, Reece, and their collaborators showed that if a portion of the dark matter is self-interacting, then these particles will collapse into a dark galactic disk that overlaps with the ordinary baryonic disk .

Did a thin disk of dark matter trigger extinction events like the one that snuffed out the dinosaurs? The evidence is still far from compelling. First, the periodicity in Earth’s cratering rate is not clearly established, because a patchy crater record makes it difficult to see a firm pattern. It is also unclear what role comets may have played in the mass extinctions. The prevailing view is that the Chicxulub crater, which has been linked to the dinosaur extinction 66 million years ago, was created by a giant asteroid, instead of a comet. Randall and Reece were careful in acknowledging at the outset that “statistical evidence is not overwhelming” and listing various limitations for using a patchy crater record. But the geological data is unlikely to improve in the near future, unfortunately.

On the other hand, advances in astronomical data are expected with the European Space Agency’s Gaia space mission, which is currently studying the Milky Way in unprecedented detail. Gaia will observe millions of stars and measure their precise distances and velocities. These measurements should enable astronomers to map out the surface-density of the dense galactic disk as a function of height. Close to the plane, astronomers could then directly see whether there is a “disk within the disk” that has much more mass than we could account for with the ordinary baryonic matter. Evidence of such a dark disk would allow better predictive modeling of the effects on comets and on the life of our planet.>>
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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby Boomer12k » Thu Nov 09, 2017 9:24 pm

I would think, that with "stars in every direction", we would not get a very good "Deep Field View", over there...

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby neufer » Thu Nov 09, 2017 11:39 pm

Try saying "aquatically intimidating" 5 times fast.
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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby pnelson » Fri Nov 10, 2017 1:16 am

If you take this older APOD image of NGC 1055, rotate it 90 degrees anti-clockwise, and compare it to today's image, they are clearly 180 degrees out of synch. I'm curious to know if that is the result of the instrumentation used to observe the galaxy, or a result of the image processing methods. Which is the correct orientation?

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby neufer » Fri Nov 10, 2017 3:51 am

pnelson wrote:
If you take this older APOD image of NGC 1055, rotate it 90 degrees anti-clockwise, and compare it to today's image, they are clearly 180 degrees out of synch. I'm curious to know if that is the result of the instrumentation used to observe the galaxy, or a result of the image processing methods. Which is the correct orientation?

If you take this older APOD image of NGC 1055,
rotate it 90 degrees clockwise North will be up. :arrow:

Today's APOD is the mirror image of that with North down.
Art Neuendorffer

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby daddyo » Fri Nov 10, 2017 5:06 am

Alex675 wrote:There is a strange-shaped backgound galaxy, top right of the image.


This is known as the Tie Fighter galaxy

pnelson

Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby pnelson » Fri Nov 10, 2017 2:39 pm

@neufer: Well yes, an image that has been rotated by 180 degrees is, by definition, it's mirror image. I appreciate you re-phrasing my point into more common lay terms and expanding upon it, but that doesn't answer my question. One of these georgeous images is a scientifically accurate repesentation of what an earth-bound observer might see, the other is just a pretty picture. Which is which, and why was the inaccurate image not notated as such?

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby Chris Peterson » Fri Nov 10, 2017 2:44 pm

pnelson wrote:@neufer: Well yes, an image that has been rotated by 180 degrees is, by definition, it's mirror image.

No, it isn't. Rotation and mirroring are different things.

I appreciate you re-phrasing my point into more common lay terms and expanding upon it, but that doesn't answer my question. One of these georgeous images is a scientifically accurate repesentation of what an earth-bound observer might see, the other is just a pretty picture. Which is which, and why was the inaccurate image not notated as such?

Neither is inaccurate. Rotation is always arbitrary (if you were looking at this in the sky, its apparent rotation would depend on the direction you were facing). Mirroring is simply a matter of convention. It is common when showing astronomical images to also identify the orientation. The most common convention is north-up, east-left. But that's just a convention.
Chris

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby neufer » Fri Nov 10, 2017 2:49 pm

pnelson wrote:@neufer: Well yes, an image that has been rotated by 180 degrees is, by definition, it's mirror image. I appreciate you re-phrasing my point into more common lay terms and expanding upon it, but that doesn't answer my question. One of these georgeous images is a scientifically accurate repesentation of what an earth-bound observer might see, the other is just a pretty picture. Which is which, and why was the inaccurate image not notated as such?

An image that has been rotated by 180 degrees is, by definition, 2 mirror images: right to left PLUS up to down. A scientifically accurate representation of what an earth-bound observer might see is the one that I posted NOT the mirror image shown in the APOD.
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pnelson

Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby pnelson » Fri Nov 10, 2017 6:33 pm

This conversation seems to be focusing on the definition of mirror images. That was not my intent.

I noticed that the two APOD images appeared to be at odds with each other, so my intent was to determine which image most accurately represents what an earthbound observer might see. @neufer, there are three images represented in this discussion, two from APOD, and the wikimedia image that you uploaded. Which are you saying is correct, and if you don't mind, how are you able to make that determination? And thanks for helping too.

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby neufer » Fri Nov 10, 2017 6:55 pm

pnelson wrote:
I noticed that the two APOD images appeared to be at odds with each other, so my intent was to determine which image most accurately represents what an earthbound observer might see. @neufer, there are three images represented in this discussion, two from APOD, and the wikimedia image that you uploaded. Which are you saying is correct, and if you don't mind, how are you able to make that determination? And thanks for helping too.

It is the same image that one gets if one goes to WIkipedia

and taps on the WikiSky map Coordinates at the upper right: 02h 41m 45.2s, +00° 26′ 35″
Art Neuendorffer

Tom W.

Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby Tom W. » Tue Nov 14, 2017 4:48 pm

The bright yellow star under the right edge of the Galaxy in this image, seen up close appears to have a ring of material seen nearly edge-on. If true, could this be pre-planatary material?

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Re: APOD: NGC 1055 Close-up (2017 Nov 09)

Postby rstevenson » Tue Nov 14, 2017 7:06 pm

Tom W. wrote:The bright yellow star under the right edge of the Galaxy in this image, seen up close appears to have a ring of material seen nearly edge-on. If true, could this be pre-planatary material?

Could you do a screen grab and point out on it which star you're referring to?

Rob


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