APOD: Deep Field: The Large Magellanic Cloud (2023 Mar 07)

[APOD Robot]

Deep Field: The Large Magellanic Cloud

Explanation: Is this a spiral galaxy? No. Actually, it is the Large Magellanic Cloud (LMC), the largest satellite galaxy of our own Milky Way Galaxy. The LMC is classified as a dwarf irregular galaxy because of its normally chaotic appearance. In this deep and wide exposure, however, the full extent of the LMC becomes visible. Surprisingly, during longer exposures, the LMC begins to resemble a barred spiral galaxy. The Large Magellanic Cloud lies only about 180,000 light-years distant towards the constellation of the Dolphinfish (Dorado). Spanning about 15,000 light-years, the LMC was the site of SN1987A, the brightest and closest supernova in modern times. Together with the Small Magellanic Cloud (SMC), the LMC can be seen in Earth's southern hemisphere with the unaided eye.

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[madtom1999]

When you drop iron filings onto a bit of paper over a magnet they tend to clump into 'rays'. It seems reasonable to assume gravity will have a similar effect and tend to turn putative disks into arms. I'm betting this happens at solar system levels too and this would mean planets could easily form before the star ignites and thus not require mind-boggling interventions of planets changing orbits and water thats been blasted away by the solar wind magically returning.

[bystander]

Explanation: Is this a spiral galaxy? No. ... The LMC is classified as a dwarf irregular galaxy because of its normally chaotic appearance. In this deep and wide exposure, however, the full extent of the LMC becomes visible. Surprisingly, during longer exposures, the LMC begins to resemble a barred spiral galaxy. ...

The Large Magellanic Cloud (LMC) ... is classified as a Magellanic spiral. It contains a stellar bar that is geometrically off center, suggesting that it was a barred dwarf spiral galaxy before its spiral arms were disrupted, likely by tidal interactions from the Small Magellanic Cloud (SMC) and the Milky Way's gravity. ...

[Ann]

Explanation: Is this a spiral galaxy? No. ... The LMC is classified as a dwarf irregular galaxy because of its normally chaotic appearance. In this deep and wide exposure, however, the full extent of the LMC becomes visible. Surprisingly, during longer exposures, the LMC begins to resemble a barred spiral galaxy. ...

The Large Magellanic Cloud (LMC) ... is classified as a Magellanic spiral. It contains a stellar bar that is geometrically off center, suggesting that it was a barred dwarf spiral galaxy before its spiral arms were disrupted, likely by tidal interactions from the Small Magellanic Cloud (SMC) and the Milky Way's gravity. ...

I agree with you, bystander. The Large Magellanic Cloud does have spiral-like features.

This is portrait of the LMC in far infrared and radio light. ESA, NASA, NASA-JPL,
Caltech, Christopher Clark (STScI), S. Kim (Sejong University), T. Wong (UIUC)

You can see the beginnings of spiral arms here.

Ann

[Chris Peterson]

When you drop iron filings onto a bit of paper over a magnet they tend to clump into 'rays'. It seems reasonable to assume gravity will have a similar effect and tend to turn putative disks into arms. I'm betting this happens at solar system levels too and this would mean planets could easily form before the star ignites and thus not require mind-boggling interventions of planets changing orbits and water thats been blasted away by the solar wind magically returning.

Iron filings line up the way they do because of the polar nature of magnetic fields. Field lines form between poles. The same thing happens with electric fields. Gravity is not bipolar, so its behavior is very different. There are no field lines as such. Arms in spiral galaxies form because of interactions between moving masses.

There is nothing we know of to suggest a mechanism for planets to form except in accretion discs around large concentrations of mass. Concentrations of solar or larger mass.

[De58te]

"The Large Magellanic Cloud lies only about 180,000 light-years distant."
This is a "What if" exercise to ponder. What if this wasn't the Milky Way, but the Andromeda Galaxy in this place and the LMC would still be the same distance away. Since the Andromeda's radius is 110,000 light years and we the Solar System would be in an opposing outer arm, the LMC would still belong in the Andromeda Galaxy just on the opposite side.

[Spif]

What really struck me about this image is how MANY foreground stars there are. Even the dim dots are solar systems (though some of those could be noise). Just about every other pixel is a system, it seems.

[Fred the Cat]

Apparently studying dwarf galaxies associated with other galaxies is challenging but may shed light on our own. Lots of them so business may be booming.

I'm constantly amazed how far we can see with the "aided" eye.

[starsurfer]

I get the impression this used to be a barred spiral galaxy in the past.

[AVAO]

What really struck me about this image is how MANY foreground stars there are. Even the dim dots are solar systems (though some of those could be noise). Just about every other pixel is a system, it seems.

Great work!

"The Large and Small Magellanic Clouds are satellite galaxies of the Milky Way Galaxy. The parallax data in the Gaia EDR3 dataset allows the foreground stars to be removed for clarity. Color saturation has ben enhanced 8x to show relative temperature differences between the stars using a white balance temperature of 4550K. This image was rendered by bsrender (https://github.com/kevinloch/bsrender) using the star records from the Gaia EDR3 dataset (https://www.cosmos.esa.int/web/gaia/earlydr3). The original 16k rendering has been scaled down to 8k."

LMC and SMC rendered from Gaia EDR3 data with foreground stars removed:

in biggg: https://upload.wikimedia.org/wikipedia/ ... -s1-s8.png
https://en.wikipedia.org/wiki/Magellani ... -s1-s8.png

[VictorBorun]

When you drop iron filings onto a bit of paper over a magnet they tend to clump into 'rays'. It seems reasonable to assume gravity will have a similar effect and tend to turn putative disks into arms. I'm betting this happens at solar system levels too and this would mean planets could easily form before the star ignites and thus not require mind-boggling interventions of planets changing orbits and water thats been blasted away by the solar wind magically returning.

Iron filings line up the way they do because of the polar nature of magnetic fields. Field lines form between poles. The same thing happens with electric fields. Gravity is not bipolar, so its behavior is very different. There are no field lines as such. Arms in spiral galaxies form because of interactions between moving masses.

There is nothing we know of to suggest a mechanism for planets to form except in accretion discs around large concentrations of mass. Concentrations of solar or larger mass.

Why, gravity field lines must be there, they just do not make a particle to attract to its neighbour in the same line and repulse from its neighbour at another line — like a magnetic field line does, to iron dust particles.

I wonder why some accretion disks have wide spiral arms while other discs have tight spiral arms or even rings.
Saturn has just rings; no arms…
Must a disk galaxy experience a pair of jets in the disk plane from the central black hole to create a pair of radial arms that become spiral arms after a billion years?

[Chris Peterson]

When you drop iron filings onto a bit of paper over a magnet they tend to clump into 'rays'. It seems reasonable to assume gravity will have a similar effect and tend to turn putative disks into arms. I'm betting this happens at solar system levels too and this would mean planets could easily form before the star ignites and thus not require mind-boggling interventions of planets changing orbits and water thats been blasted away by the solar wind magically returning.

Iron filings line up the way they do because of the polar nature of magnetic fields. Field lines form between poles. The same thing happens with electric fields. Gravity is not bipolar, so its behavior is very different. There are no field lines as such. Arms in spiral galaxies form because of interactions between moving masses.

There is nothing we know of to suggest a mechanism for planets to form except in accretion discs around large concentrations of mass. Concentrations of solar or larger mass.

Why, gravity field lines must be there, they just do not make a particle to attract to its neighbour in the same line and repulse from its neighbour at another line — like a magnetic field line does, to iron dust particles.

Field lines form closed paths. That is not possible with gravity.

[Ann]

What really struck me about this image is how MANY foreground stars there are. Even the dim dots are solar systems (though some of those could be noise). Just about every other pixel is a system, it seems.

Great work!

"The Large and Small Magellanic Clouds are satellite galaxies of the Milky Way Galaxy. The parallax data in the Gaia EDR3 dataset allows the foreground stars to be removed for clarity. Color saturation has ben enhanced 8x to show relative temperature differences between the stars using a white balance temperature of 4550K. This image was rendered by bsrender (https://github.com/kevinloch/bsrender) using the star records from the Gaia EDR3 dataset (https://www.cosmos.esa.int/web/gaia/earlydr3). The original 16k rendering has been scaled down to 8k."

LMC and SMC rendered from Gaia EDR3 data with foreground stars removed:

in biggg: https://upload.wikimedia.org/wikipedia/ ... -s1-s8.png
https://en.wikipedia.org/wiki/Magellani ... -s1-s8.png

Fantastic and amazing image from Gaia data by bsrender, AVAO! Do look at the incredible detail in the full size of it!

The only problem with Gaia images is that all stars are represented by a tiny dot of a fixed size. This means that, according to Gaia, Alpha, Beta and Proxima Centauri are all represented by a dot of the same size:

From left to right: Alpha Centauri, the Sun, Beta Centauri and Proxima Centauri

So to Gaia, all stars are equal! But this causes problems when you are trying to find a bright open cluster in a Gaia image. Really, where is the Tarantula Nebula and super-bright Tarantula cluster R 136a in the image generated from Gaia data?

Where is the Tarantula?

Ann

[Chris Peterson]

The only problem with Gaia images is that all stars are represented by a tiny dot of a fixed size. This means that, according to Gaia, Alpha, Beta and Proxima Centauri are all represented by a dot of the same size:

This is only a problem because it replaces our poor eyes with an accurate representation of the sky. Because in reality, all stars are the same size! But the nature of optics and our eyes is that we see brighter stars as apparently larger... even though they are, ideally, all dimensionless points. It really messes with our brains when we actually see them that way, though.

[VictorBorun]

offtopic on field lines made visible

gravity field lines must be there, they just do not make a particle to attract to its neighbour in the same line and repulse from its neighbour at another line — like a magnetic field line does, to iron dust particles.

Field lines form closed paths. That is not possible with gravity.

1) not imortant for precipitation and visibility whether the field lines eventually somewhere far off the picture go converge at a mass, electric charge, fantastic magnetic monopole or whatever; as long as in the observed region they tend to repulse from each other while trying to contract. Magnetic lines are the greatest at it: when they align little magnets in the media, they do precipitate to distinct parallel lanes
2) visualisation by iron dust is of the scale of a laboratory table. Visualisation by Sun's chromospheric protuberances is 1 light second long at the longest and so far we have not really seen how two distinct coils were pressed together so hard that the repulsion got overpowered and the two merge with a mighty flash — I mean the flash we can see, but the two coils remain just our best guess so far.

I wonder if magnetic lines can precipitate to dusty lanes in galactic arms

[Chris Peterson]

offtopic on field lines made visible

gravity field lines must be there, they just do not make a particle to attract to its neighbour in the same line and repulse from its neighbour at another line — like a magnetic field line does, to iron dust particles.

Field lines form closed paths. That is not possible with gravity.

1) not imortant for precipitation and visibility whether the field lines eventually somewhere far off the picture go converge at a mass, electric charge, fantastic magnetic monopole or whatever; as long as in the observed region they tend to repulse from each other while trying to contract. Magnetic lines are the greatest at it: when they align little magnets in the media, they do precipitate to distinct parallel lanes
2) visualisation by iron dust is of the scale of a laboratory table. Visualisation by Sun's chromospheric protuberances is 1 light second long at the longest and so far we have not really seen how two distinct coils were pressed together so hard that the repulsion got overpowered and the two merge with a mighty flash — I mean the flash we can see, but the two coils remain just our best guess so far.

I wonder if magnetic lines can precipitate to dusty lanes in galactic arms

Magnetic fields and electric fields can align dust at small scales, as in nebulas. Both fields are very weak in galaxies, though.