Starship Asterisk*

I said I would write a little about NGC 1097, and I will, even though it's almost time for a new APOD!

I'm fascinated by the morphology of NGC 1097. It has an almost perfectly circular (but actually spiral-shaped) merrily starforming bright inner ring surrounding the nucleus. And it has a long oval-shaped bar-bulge which is surrounded by a large, rather faint but still starforming outer ring.


[float=left][img3="Bright starforming inner ring, long yellow bar-bulge (with some star formation) and a faint, here barely visible outer ring. Credit: ESA/Hubble & NASA."]https://64.media.tumblr.com/7744044fead63382746d7b5518184084/tumblr_pvzloeu33M1ucbyswo1_1280.jpg[/img3]
[/float][float=right][img3="Portrait of NGC 1097 through seven different filters from ultraviolet to near infrared. The picture is 'upside down' relatively to the the image next to it, but neither is north up. Credit: ESA/Hubble & NASA, D. Sand, K. Sheth"]https://cdn.spacetelescope.org/archives/images/screen/potw2211a.jpg[/img3][/float]
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NGC 1097 has two arms, but one arm is severely distorted and broken up due to the presence of a small but clearly relatively massive satellite dwarf galaxy that is positively entangled in one of the arms of NGC 1097. This morphology is clearly seen in a Spitzer infrared image:


[img3="In this Spitzer image, red means dust, blue means (cool) stars. Note the all-blue ('dust-free') quite bright-looking satellite galaxy at left, entangled in the broken-up arm of NGC 1097. Credit: NASA/JPL-Caltech"]https://upload.wikimedia.org/wikipedia/commons/thumb/8/80/Coiled_Galaxy.jpg/800px-Coiled_Galaxy.jpg[/img3]


All right. Take a look at this JWST-HST-VLT/MUSE-ALMA image:


[img3=""]https://preview.redd.it/double-rings-of-barred-spiral-galaxy-ngc-1512-nircam-miri-v0-hf0jgp6bccga1.png?width=640&crop=smart&auto=webp&s=eb32a5d94dfcccb3bad6c23a46297c4a8f7d66e1[/img3]


Well, wow. Doesn't it look good? Talk about an inner ring + outer ring barred spiral galaxy! But really, is this truly NGC 1097?

It is not. It is NGC 1512. And there is a fantastic GALEX image showing how its entire arm system NGC 1512 is broken up by its interaction with a small satellite galaxy of NGC 1512, namely NGC 1510!


[img3="NGC 1512 and its satellite galaxy NGC 1510 in ultraviolet light by GALEX. Credit: NASA/JPL-Caltech."]https://upload.wikimedia.org/wikipedia/commons/6/65/Ngc1512_nasajpl.jpg?20070830142738[/img3]


I find it absolutely fascinating that NGC 1097 and NGC 1512 show so many similarities. Even though they are, of course, different too.

Ann

[quote=johnnydeep post_id=334355 time=1697057504 user_id=132061]
I find it pretty strange that the jets from a likely ancient collision, and shown in the "[url=https://apod.nasa.gov/apod/ap221116.html]faint jets[/url]" link are so arrow-straight (with the exception of the even more strange "T" bar at the end of the lower jet!). Why would the jets not be - at least somewhat - curved?


[img2]https://apod.nasa.gov/apod/image/2211/NGC-1097-LRGB_Ha-rev-12-2022.jpg[/img2]
[/quote]

I agree that it is strange that the jets are so arrow-straight. They do look like gaseous remnants of outbursts from the accretion disk of the black hole. But since they are made of stars, not gas, I suppose we have to accept that they are star streams and thus remnants of galaxies that have been "eaten" by NGC 1097.

Ann

I find it pretty strange that the jets from a likely ancient collision, and shown in the "[url=https://apod.nasa.gov/apod/ap221116.html]faint jets[/url]" link are so arrow-straight (with the exception of the even more strange "T" bar at the end of the lower jet!). Why would the jets not be - at least somewhat - curved?


[img2]https://apod.nasa.gov/apod/image/2211/NGC-1097-LRGB_Ha-rev-12-2022.jpg[/img2]

[attachment=1]Ngc1097wSn_Miller_1008.gif[/attachment]
Star dies in NGC1097! Sad for any life that may have lived there!
[attachment=0]f7a40951e62342cf0671e34dcb8dbec2.jpg[/attachment]
Kitty's photo taken by surprise!

[quote="APOD Robot" post_id=334328 time=1696997472 user_id=128559]
[url=https://apod.nasa.gov/apod/ap231011.html] [img]https://apod.nasa.gov/apod/calendar/S_231011.jpg[/img] [size=150]NGC 1097: Spiral Galaxy with Supernova[/size][/url]
[/quote]

[img]https://apod.nasa.gov/apod/image/2310/Ngc1097wSn_Miller_1008.gif[/img]
today's APOD

Would have been an interesting image with JWST too...
[img2]https://live.staticflickr.com/65535/53251725449_9fe18724b0_c.jpg[/img2]
[size=75]Here the version with the SST / Jac Berne (flickr)
bigger:[url]https://live.staticflickr.com/65535/53251725449_9acc74028b_o.jpg[/url][/size]

[quote="Chris Peterson" post_id=334349 time=1697047386 user_id=117706]
[quote=MoonRockMan post_id=334348 time=1697045538 user_id=146309]
Any idea if the differences between the two images--apart from the supernova--are because of differences in sky conditions at the respective times or because of brightening from the nova?
[/quote]

Nothing to do with the SN. It's just really difficult image processing to create two identical images of the same object taken at different times, even with identical sky conditions. Even more so with color. A series of non-linear stretches is normally part of the processing workflow, and the exact details are seldom recorded. So matching a new image to an old one is just done by eyeball.
[/quote]

Very interesting! Thanks for the explanation.

[quote=MoonRockMan post_id=334348 time=1697045538 user_id=146309]
Any idea if the differences between the two images--apart from the supernova--are because of differences in sky conditions at the respective times or because of brightening from the nova?
[/quote]

Nothing to do with the SN. It's just really difficult image processing to create two identical images of the same object taken at different times, even with identical sky conditions. Even more so with color. A series of non-linear stretches is normally part of the processing workflow, and the exact details are seldom recorded. So matching a new image to an old one is just done by eyeball.

Any idea if the differences between the two images--apart from the supernova--are because of differences in sky conditions at the respective times or because of brightening from the nova?

[float=left][attachment=0]APOD 11October 2023.png[/attachment][c][size=85][color=#0040FF]NGC 1097: Spiral Galaxy with Supernova.
Image Data: Telescope Live (Chile); Image Processing & Copyright: Bernard Miller[/color][/size][/c][/float]
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Interesting! I like supernovas. As you could see from one of the links in the caption, SN 2023rve is a type II supernova, which means that it's a core-collapse supernova whose massive progenitor exploded when it had built up an iron core. The stars that end up as type II supernovas are massive stars that fuse and use up all their available fuel in their fight against gravity until they have created an inert iron core, after which their supernova demise is imminent.


[float=left][img3="The iron core of an evolved high-mass star. The image shows the fusion processes leading up to the formation of an iron core. The demise of this star is imminent. Credit: I don't know."]https://www.astronomynotes.com/evolutn/redgiant-core.png[/img3][/float][float=right][img3="Supernova 1987 A near the Tarantula Nebula in the Large Magellanic Cloud, a type II supernova. Credit: ESA."]https://upload.wikimedia.org/wikipedia/commons/thumb/0/0a/Eso0708a.jpg/420px-Eso0708a.jpg[/img3][/float]
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Type II supernovas vary a lot when it comes to absolute luminosity. They are not like [url=https://www.sciencedirect.com/topics/physics-and-astronomy/type-ia-supernovae]type Ia supernovas[/url], which are white dwarf stars that accrete mass until they explode when their cores exceed 1.4 solar masses. When supernovas type Ia explode, they literally "go up in smoke" and leave no remnant behind, since all of the mass they contain "is turned into energy". (I'm sure that's not exactly correct, Chris. Please do correct me.)


[float=left][img3="A white dwarf fed by a normal star reaches the critical mass and explodes as a type Ia supernova. Credit: NASA/CXC/M Weiss"]https://scx2.b-cdn.net/gfx/news/hires/2014/image001.jpg[/img3][/float][float=right][img3="Type Ia supernova SN 1994D in NGC 4526.
Credit: High-Z Supernova Search Team/HST/NASA"]https://astronomy.swin.edu.au/cms/cpg15x/albums/userpics/typeia1.jpg[/img3][/float]
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Type II supernovas are different, since they almost always leave a remnant behind, usually a neutron star. Sometimes they leave a black hole behind, but I don't think that we have witnessed an explosion where astronomers have been confident that the stellar core had turned into a black hole.

Type II supernovas don't have a typical luminosity, since they can explode at different masses and with different amounts of gas and dust surrounding the core. I think, however, that type Ia supernovas are often visually brighter than type II supernovas. Type Ia supernovas do have a "typical peak luminosity", which is magnitude −19.5. Type II supernovas are often not that visually bright. But they are often more powerful, since most of their energy is released as a tsunami of invisible neutrinos.

As for SN2023rve, its peak apparent magnitude was +14. The apparent magnitude of the entire galaxy itself, NGC 2097, is 9.5, according to my software. In astronomy, the lower the magnitude is, the brighter is the object.

I'd like to write a lot about NGC 1097 as well, but I have no time. So I'll stop now.

Ann

P.S. I really, really recommend [url=https://en.wikipedia.org/wiki/Type_Ia_supernova#/media/File:SN2018gv.gif]this gif[/url] where you can see the evolution of a type Ia supernova! :D

P.P.S. This is my post number 13000. If Art Neuendorffer had been here, he would have made a post about that in the [url=https://asterisk.phy.mtu.edu/viewtopic.php?t=18222&sid=4e295e9785a4f3aa9c20f547e7b0bc43&start=775]Thousand Post Club[/url] thread.

Art, I miss you. :(

[url=https://apod.nasa.gov/apod/ap231011.html] [img]https://apod.nasa.gov/apod/calendar/S_231011.jpg[/img] [size=150]NGC 1097: Spiral Galaxy with Supernova[/size][/url]

[b] Explanation: [/b] What's happening in the lower arm of this spiral galaxy? A [url=https://imagine.gsfc.nasa.gov/science/objects/supernovae1.html]supernova[/url]. Last month, supernova [url=https://en.wikipedia.org/wiki/SN_2023rve]SN 2023rve[/url] was discovered with [url=https://en.wikipedia.org/wiki/United_Arab_Emirates]UAE[/url]'s Al-Khatim Observatory and later [url=https://www.astronomycenter.net/articles/2023/09/10/sn2023rve?l=en]found[/url] to be consistent with the death explosion of a massive star, possibly leaving behind a [url=https://science.nasa.gov/astrophysics/focus-areas/black-holes/]black hole[/url]. Spiral galaxy [url=https://en.wikipedia.org/wiki/NGC_1097]NGC 1097[/url] is a relatively close 45 million [url=https://spaceplace.nasa.gov/light-year/en/]light year[/url]s away and visible with a small telescope toward the southern constellation of the Furnace ([url=https://chandra.harvard.edu/photo/constellations/fornax.html]Fornax[/url]). The galaxy is notable not only for its [url=https://apod.nasa.gov/apod/ap230508.html]picturesque spiral arms[/url], but also for [url=https://apod.nasa.gov/apod/ap221116.html]faint jets[/url] consistent with ancient [url=https://apod.nasa.gov/apod/ap191116.html]star streams[/url] left over from a [url=https://youtu.be/lXy3B2K47Qg]galactic collision[/url] -- possibly with the small galaxy seen between its arms on the lower left. The [url=https://azstarman.net/CDK/NGC1097_TL_SN.htm]featured image[/url] highlights the new supernova by [url=https://www.livescience.com/why-do-we-blink.html]blinking[/url] between two exposures taken several months apart. [url=https://i.pinimg.com/1200x/f7/a4/09/f7a40951e62342cf0671e34dcb8dbec2.jpg]Finding supernovas[/url] in nearby galaxies can be important in determining the [url=https://apod.nasa.gov/diamond_jubilee/debate20.html]scale[/url] and expansion rate of our [url=https://apod.nasa.gov/apod/ap231006.html]entire universe[/url] -- a topic currently of [url=https://blogs.nasa.gov/webb/2023/09/12/webb-confirms-accuracy-of-universes-expansion-rate-measured-by-hubble-deepens-mystery-of-hubble-constant-tension/]unexpected tension[/url] and [url=https://apod.nasa.gov/debate/debate.html]much debate[/url].


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