APOD: Barred Spiral Galaxy NGC 1365 from Webb (2023 Feb 18)

[APOD Robot]

Barred Spiral Galaxy NGC 1365 from Webb

Explanation: A mere 56 million light-years distant toward the southern constellation Fornax, NGC 1365 is an enormous barred spiral galaxy about 200,000 light-years in diameter. That's twice the size of our own barred spiral Milky Way. This sharp image from the James Webb Space Telescope's Mid-Infrared Instrument (MIRI) reveals stunning details of this magnificent spiral in infrared light. Webb's field of view stretches about 60,000 light-years across NGC 1365, exploring the galaxy's core and bright newborn star clusters. The intricate network of dusty filaments and bubbles is created by young stars along spiral arms winding from the galaxy's central bar. Astronomers suspect the gravity field of NGC 1365's bar plays a crucial role in the galaxy's evolution, funneling gas and dust into a star-forming maelstrom and ultimately feeding material into the active galaxy's central, supermassive black hole.

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[Ann]

Let's take a look at NGC 1365, shall we?

Huge barred spiral NGC 1365. The central bar of NGC 1365 influences star formation throughout the entire galaxy and conceals a supermassive black hole hidden behind multitudes of newly formed stars. Credit: Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA Image processing: Travis Rector (University of Alaska Anchorage/NSF’s NOIRLab), Jen Miller (Gemini Observatory/NSF’s NOIRLab), Mahdi Zamani & Davide de Martin (NSF’s NOIRLab)

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According to Wikipedia, NGC 1365 is believed to be about 200,000 light-years in diameter, which is twice the size of the Milky Way. This is a HUGE galaxy and "extremely barred"! Cheers! (No, it means that NGC 1365, like all barred galaxies, has a sort of "crossbar of stars" running through its middle. Usually there is a pair of dust lanes in the bar, too, one on each side of the nucleus, but not always. NGC 4314 has a crossbar of stars, but there are no dust lanes in the bar.)

Actually, NGC 1365 has two bars , and it's the inner one that looks so brilliantly bright in today's APOD:

Barred Spiral Galaxy NGC 1365 from Webb. Image Credit: NASA, ESA, CSA, Janice Lee (NOIRLab) - Processing: Alyssa Pagan (STScI)

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What are we seeing? Let's compare the James Webb MIRI image with two other images of the inner bar of NGC 1365:

NGC 1365 in ultraviolet, optical and near infrared light. Credit: ESA/Hubble & NASA, J. Lee and the PHANGS-HST Team. Acknowledgement: Judy Schmidt (Geckzilla)

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The inner bar of NGC 1365, as observed by the MUSE instrument on ESO’s Very Large Telescope (VLT) in Chile. Credit: ESO/TIMER survey

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As you can see, it is not overwhelmingly obvious in the ESA/Hubble & NASA "mostly optical" image that the inner bar of NGC 1365 is chock full of star formation. But in the ESO image, captured by the MUSE instrument, whose every detector is apparently sensitive to a huge number of wavelengths simultaneously, the inner bar becomes much more impressive. All the red stuff that we can see in the ESO image is apparently dust, which we also see in the JWST/MIRI image.

Let's compare the MIRI picture of NGC 1365 with MIRI images of galaxies M100 and M61. Let's start with optical and MIRI pictures of M100:

M100 in optical light. You can see that the inner ring surrounding the nucleus is very bright. Credit: Hubble Legacy Archive, NASA, ESA - Processing & Licence: Judy Schmidt

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M100 in mid infrared light. Note the bright center and the elegant arms. Author: JWST/MIRI.

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The inner ring of M100 is very bright in both visible and infrared light. There are a lot of bright stars and a lot of dust in the center of M100.

M100 is not an "overwhelmingly barred" galaxy, although it does have an incipient bar (since it is classified as an intermediate galaxy). But a galaxy that does have a large and impressive bar is M66:

M66. Its bar is long and impressive, but its central part is not as bright and dominant as the inner ring of M100. Credit: ESA/Hubble & NASA Acknowledgements: G. Chapdelaine, L. Limatola, and R. Gendler.

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M66 in mid infrared light. Note the elegant and bright arms and the somewhat less impressive center. Author: JWST/MIRI.

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The center of M66 is nowhere near as impressive as the center of M100, neither in optical nor in mid infrared light.


NGC 1365 has both an impressive overall bar structure and an inner bar that is very bright and impressive in optical light and perhaps even more at mid infrared wavelengths.

Finally, what are those red rays from the very center of NGC 1365?

Red rays from the center of NGC 1365 MIRI.png

Why, those are the signature of the supermassive black hole of NGC 13645 accreting matter and acting up! Note that neither M100 nor M66 has these rays. Their black holes are more like well-mannered school children compared with the big black hole bully of NGC 1365!

Ann

[AVAO]

...
Finally, what are those red rays from the very center of NGC 1365?

Red rays from the center of NGC 1365 MIRI.png

Why, those are the signature of the supermassive black hole of NGC 13645 accreting matter and acting up! Note that neither M100 nor M66 has these rays. Their black holes are more like well-mannered school children compared with the big black hole bully of NGC 1365!

Ann

I think the red rays are optical fragments from 3 bright sources (center and near node) and not a "real" phenomenon.
...but of course they look great in the picture, spiced up in a nice red...

Compare NGC 7496 (JWST MIRI)

Credit: NASA, ESA, CSA, and J. Lee (NOIRLab), A. Pagan (STScI)

[orin stepanek]

JWSTMIRI_ngc1365_1024.png

Awesome! Even the JWST gives us great views! W hat more could one want?

[richardschumacher]

Finally, what are those red rays from the very center of NGC 1365?

Surely the rays themselves are JWST's diffraction spikes. But are the bright objects foreground? If they are actually in NGC 1365, then wowsers!

[bystander]

viewtopic.php?t=42951

[Chris Peterson]

Finally, what are those red rays from the very center of NGC 1365?

While the rays are optical artifacts, they actually contain useful information. We see such diffraction spikes around bright sources. Sources which saturate the camera pixels, meaning that we have no intensity information other than "greater than x". But a bit of clever math can use the intensity and length of the spikes, which are not saturated, to approximate the intensity of the source.

[Fred the Cat]

If first results aren’t impressive enough regarding NGC 1365, I think the next 20 years of JWST will provide plenty of “ phangs”.

[Ann]

...
Finally, what are those red rays from the very center of NGC 1365?

Red rays from the center of NGC 1365 MIRI.png

Why, those are the signature of the supermassive black hole of NGC 13645 accreting matter and acting up! Note that neither M100 nor M66 has these rays. Their black holes are more like well-mannered school children compared with the big black hole bully of NGC 1365!

Ann

I think the red rays are optical fragments from 3 bright sources (center and near node) and not a "real" phenomenon.
...but of course they look great in the picture, spiced up in a nice red...

APOD Robot wrote about NGC 1365:

Astronomers suspect the gravity field of NGC 1365's bar plays a crucial role in the galaxy's evolution, funneling gas and dust into a star-forming maelstrom and ultimately feeding material into the active galaxy's central, supermassive black hole.

This suggests to me that NGC 1365 has an active black hole, which may show up as a particularly bright source in MIRI images.

MIRI has photographed at least one other galaxy whose center also displays red rays, NGC 7496:

NGC 1365 (MIRI image)

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NGC 7496 (MIRI image)

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NASA/ESA/Hubble wrote about the MIRI picture of NGC 7496:

At the centre of NGC 7496, a barred spiral galaxy, is an active galactic nucleus (AGN). An AGN is a supermassive black hole that is emitting jets and winds. The AGN glows brightly at the centre of this Webb image.

So NGC 7496, which displays the same kind of central red rays as NGC 1365, has an active black hole that glows brightly at mid infrared wavelengths. I choose to believe that the red rays of the center of NGC 1365 are also photographic artifacts caused by the mid infrared brightness of the black hole of NGC 1365.

Ann

[AVAO]

So NGC 7496, which displays the same kind of central red rays as NGC 1365, has an active black hole that glows brightly at mid infrared wavelengths. I choose to believe that the red rays of the center of NGC 1365 are also photographic artifacts caused by the mid infrared brightness of the black hole of NGC 1365.
Ann

ThanX Ann & Chris for the many detailed information.

To me, the dominance of the red channel is arguably scientifically correct.
As a result, a lot of details are simply lost in the core area

Click to view full size image 1 or image 2

https://live.staticflickr.com/65535/522 ... 37dd_o.jpg
https://live.staticflickr.com/65535/522 ... 7bcc_o.jpg

jac berne (flickr)

[johnnydeep]

So, are these the TWO bars in NGC 1365?

two bars in ngc 1365.png

two bars in ngc 1365 jwst.png

[Ann]

So, are these the TWO bars in NGC 1365?

Click to view full size image

Click to view full size image

That's correct, Johnny.

Ann

[johnnydeep]

So, are these the TWO bars in NGC 1365?

Click to view full size image

Click to view full size image

That's correct, Johnny.

Ann