GOTD: Galaxy Of The Day

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Sat Feb 03, 2024 4:23 pm

02.02.2024 I UGC 11105 - Hubble Pictures of the Week
NASA/ESA | Original release 2024 Jan 29
This image of the spiral galaxy UGC 11105 is not as bright and vivid as some other Hubble Pictures of the Week. This softly luminous galaxy — lying in the constellation Hercules, about 110 million light-years from Earth — seems outshone by the sparkling foreground stars that surround it. The type II supernova which took place in this galaxy in 2019, while no longer visible in this image, definitely outshone the galaxy at the time!

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Sat Feb 03, 2024 4:33 pm

03.02.2024 I UGC 5189A - This Galaxy Hosted One of the Most Powerful Supernovae Ever Seen
universe today | Original release 2024 Jan 23
In 2010, an exceptionally luminous supernova exploded in a small galaxy about 150 million light-years away called UGC 5189A. The Hubble Space Telescope has kept its eye on this galaxy because of the extraordinary supernova, which for three years released more than 2.5 billion times the energy of our Sun in visible light alone. Though the supernova, named SN 2010jl, died down years ago, astronomers are still watching its aftermath. While a supernova explosion is a cataclysmic event that’s more luminous than the galaxy that hosts it, what happens after it explodes is just as compelling. An explosion that powerful changes its surroundings, and astronomers examine the aftermath to understand more about how it happened.

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Re: GOTD: Galaxy Of The Day

Post by Ann » Sat Feb 03, 2024 6:28 pm

AVAO wrote: Sat Feb 03, 2024 4:23 pm 02.02.2024 I UGC 11105 - Hubble Pictures of the Week
NASA/ESA | Original release 2024 Jan 29
This image of the spiral galaxy UGC 11105 is not as bright and vivid as some other Hubble Pictures of the Week. This softly luminous galaxy — lying in the constellation Hercules, about 110 million light-years from Earth — seems outshone by the sparkling foreground stars that surround it. The type II supernova which took place in this galaxy in 2019, while no longer visible in this image, definitely outshone the galaxy at the time!

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GOTD4Y Jac
Note how beautifully regular UGC 11105 really is, and note how little star formation there is in the arms. These two factors go hand in hand. A lot of star formation will, frankly, mess up the shape of the arms.

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Fri Feb 09, 2024 5:36 am

Ann wrote: Sat Feb 03, 2024 6:28 pm
"Note how beautifully regular UGC 11105 really is, and note how little star formation there is in the arms. These two factors go hand in hand. A lot of star formation will, frankly, mess up the shape of the arms."

Ann

ThanX Ann 4 your comment!

That's an interesting theory.

Where active star formation takes place, supernova eruptions are not far away. One thesis says that these individually or over the centuries as a collection (in star birthplaces such as the Orion Nebula not far from us) could be responsible for the "holes" and irregularities in the spiral arms, which are especially visible in the IR. But I also think that the influence of nearby galaxies in all forms has a decisive influence on the overall symmetry of a galaxy. In the case of UGC 11105 there are some, but they seem to be very far away so that no influence is visible.

PS: I also like Messier 61 on Spitzer's IR. Credit: NASA/JPL-Caltech

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Wed Feb 14, 2024 7:51 pm

04.02.2024 I HST: Hubble captures throng of spiral galaxies
phys.org | Original release 2023 Dez 29
This Hubble Picture of the Week features a richness of spiral galaxies: the large, prominent spiral galaxy on the right side of the image is NGC 1356; the two apparently smaller spiral galaxies flanking it are LEDA 467699 (above it) and LEDA 95415 (very close at its left) respectively; and finally, IC 1947 sits along the left side of the image.
...
On the other hand, while NGC 1356 and IC 1947 seem to be separated by a relative gulf in this image, IC 1947 is only about 500 million light-years from Earth. The angular distance apparent between them in this image only works out to less than four hundred thousand light-years, so they are actually much much closer neighbors in three-dimensional space than NGC 1356 and LEDA 95415!

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Wed Feb 14, 2024 8:09 pm

05.02.2024 I Gemini South Captures Twisted Dusty Disk of NGC 4753
noirlab | Original release 2024 Jan 25
Tangled dust lanes winding throughout the galactic halo of NGC 4753 suggest a turbulent merger with a dwarf galaxy over 1 billion years ago
...
Though NGC 4753 appears to be exceptionally unique, this may be a misconception. According to Steiman-Cameron, if one were to view the twisted dusty disk from directly above it likely would look no different than a standard spiral galaxy. It’s due only to our fortuitous, nearly edge-on view that we are able to see the full scope of its tangled dust lanes, meaning these peculiar features may not be as rare in the Universe as they seem.
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Re: GOTD: Galaxy Of The Day

Post by AVAO » Wed Feb 14, 2024 8:27 pm

06.02.2024 I HST: ARP 271 - Hubble Sees a Bridge of Stars Connecting Two Galaxies
Universe Today | Original release 2024 Jan 31
...
ARP 271 is one of the interacting pairs of galaxies imaged by Hubble. ARP 271 contains NGC 5427 and NGC 5426. The pair is about 130 million light-years distant and about 130 million light-years across.
...
Powerful interactions between massive galaxies like these can trigger star birth in the streams of gas and stars that bridge the galaxies. The bridge between the pair is faint in these images, but it’s there in the lower right corner of the Hubble image, and young bright blue stars highlight it. The bridge feeds gas back and forth between the galaxies, fuelling star formation.


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Re: GOTD: Galaxy Of The Day

Post by AVAO » Wed Feb 14, 2024 8:48 pm

07.02.2024 I HST: Hubble Views Irregular Galaxy ESO 245-5
NASA/ESA | Original release 2024 Feb 05
This NASA/ESA Hubble Space Telescope image shows a densely packed field of stars laid upon a background of dust, gas, and light from more distant celestial objects. There are so many stars in this image’s field of view that it may be a little tricky to discern that you are in fact looking at a galaxy. Known as ESO 245-5, this galaxy may be harder to recognize because of its apparent lack of structure, which contrasts sharply with Hubble’s spectacular images of spiral galaxies that hold seemingly ordered spiral arms of stars, gas, and dust. ESO 245-5 is an IB(s)m type of galaxy under the De Vaucouleurs galaxy classification system. This designation means that the galaxy is irregular (I) with no ordered structure. It is also barred (B) meaning it holds a dense bar of stars that crosses through its center. The third term ((s)) indicates that it has a slight spiral structure, while the last term (m) means it is a type of galaxy similar to the Large and Small Magellanic Clouds that are irregular satellite galaxies of the Milky Way. ESO 245-5 is a relatively close neighbor of the Milky Way. It is located some of 15 million light-years from Earth in the constellation Phoenix.

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Wed Feb 14, 2024 9:02 pm

08.02.2024 I HST: Galaxy AM 1054-325 - Hubble detects celestial 'string of pearls' star clusters in galaxy collisions
NASA/ESA | Original release 2024 Feb 09
When spectacular cosmic events such as galaxy collisions occur, it sets off a reaction to form new stars, and possibly new planets that otherwise would not have formed. The gravitational pull that forces the collisions between these galaxies creates tidal tails—the long thin region of stars and interstellar gas. ... Specifically, NASA's Hubble Space Telescope has homed in on 12 interacting galaxies that have long, tadpole-like tidal tails of gas, dust and a plethora of stars. Hubble's exquisite sharpness and sensitivity to ultraviolet light have uncovered 425 clusters of newborn stars along these tails, looking like strings of holiday lights.

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Sun Feb 18, 2024 1:37 pm

09.02.2024 I HST: Hubble Space Telescope Observes Trio of Interacting Galaxies
sci.news | Original release 2023 Oct 27
This Hubble image shows Arp-Madore 2339-661, a group of three interacting galaxies some 500 million light-years away in the constellation of Tucana. The color image was made from separate exposures taken in the visible and infrared regions of the spectrum with Hubble’s Advanced Camera for Surveys (ACS) and the Dark Energy Camera (DECam) on the Víctor M. Blanco 4-m telescope at Cerro Tololo Inter-American Observatory. Four filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter.

NASA has released a beautiful photo taken by the NASA/ESA Hubble Space Telescope of the galaxy group Arp-Madore 2339-661, so named because they belong to the Arp-Madore catalogue of peculiar galaxies. However, the particular peculiarity might be even odder than first meets the eye, as there are in fact three galaxies interacting here, not just two. [...] “All three galaxies lie quite close to each other and, as this image shows, they are interacting gravitationally with one another,” Hubble astronomers said. “In fact, some science literature refers to them as a ‘merging group’, meaning that they are on a course to ultimately become a single entity.”

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Sun Feb 18, 2024 1:45 pm

10.02.2024 I HST: Hubble captures galaxy NGC 3156
pys.org | Original release 2023 Sep 18
This dream-like image from the NASA/ESA Hubble Space Telescope features the galaxy known as NGC 3156. It lies about 73 million light-years from Earth, in the minor equatorial constellation Sextans. [...] Astronomers have studied NGC 3156 in many ways—from its cohort of globular clusters (roughly spherical groups of stars bound together by their gravitational attraction), to the stars being destroyed by the supermassive black hole at its heart. Using Hubble data, they compared stars near the galaxy's core to those in galaxies with similarly sized black holes. They found that NGC 3156 has a higher-than-average percentage of stars gobbled up by its supermassive black hole when compared to its counterparts.”

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Sun Feb 18, 2024 1:51 pm

11.02.2024 I HST: Hubble looks at the late-type galaxy NGC 2814
pys.org | Original release 2023 Dez 18
"This NASA Hubble Space Telescope image features NGC 2814, an irregular galaxy that lies about 85 million light-years from Earth. In this image, which was captured using Hubble's Advanced Camera for Surveys, the galaxy appears to be quite isolated: visually, it looks a little like a loose stroke of bright paint across a dark background. However, looks can be deceiving. [...] The terminology "late-type" refers to spiral and irregular galaxies, while "early type" refers to elliptical galaxies. This rather confusing terminology has led to a common misconception within the astronomy community. It is still quite widely believed that Edwin Hubble inaccurately thought that elliptical galaxies were the evolutionary precursors to spiral and irregular galaxies, and that that is the reason why ellipticals are classed as early type and spirals and irregulars are classed as late-type.

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Sun Feb 18, 2024 1:59 pm

12.02.2024 I HST: Hubble presents a holiday globe of stars in UGC 8091
pys.org | Original release 2023 Dez 20
To celebrate the holiday season, the NASA/ESA Hubble Space Telescope has captured the galaxy known as UGC 8091, which resembles a sparkling festive snow globe. With a dazzling array of wavelengths of light captured by filters on Hubble's premier scientific instruments, the millions of stars in this galaxy are being explored in more depth than ever before. [...]"

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Sun Feb 18, 2024 2:05 pm

13.02.2024 I HST: Hubble presents a holiday globe of stars in UGC 8091
pys.org | Original release 2024 Jan 24
NGC 3384, visible in this image, has many of the characteristic features of so-called elliptical galaxies. Such galaxies glow diffusely, are rounded in shape, display few visible features, and rarely show signs of recent star formation. Instead, they are dominated by old, aging, and red-hued stars. This stands in contrast to the liveliness of spiral galaxies such as our home galaxy, the Milky Way, which possess significant populations of young, blue stars in spiral arms swirling around a bright core. However, NGC 3384 also displays a hint of disk-like structure towards its center, in the form of a central "bar" of stars. Many spirals also boast such a bar, the Milky Way included; galactic bars are thought to funnel material through and around a galaxy's core, which helps maintain and fuel the activities and processes occurring there.[...]"

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Sun Feb 18, 2024 2:11 pm


13.02.2024 I HST: Hubble presents a holiday globe of stars in UGC 8091
pys.org | Original release 2024 Jan 24
NGC 3384, visible in this image, has many of the characteristic features of so-called elliptical galaxies. Such galaxies glow diffusely, are rounded in shape, display few visible features, and rarely show signs of recent star formation. Instead, they are dominated by old, aging, and red-hued stars. This stands in contrast to the liveliness of spiral galaxies such as our home galaxy, the Milky Way, which possess significant populations of young, blue stars in spiral arms swirling around a bright core. However, NGC 3384 also displays a hint of disk-like structure towards its center, in the form of a central "bar" of stars. Many spirals also boast such a bar, the Milky Way included; galactic bars are thought to funnel material through and around a galaxy's core, which helps maintain and fuel the activities and processes occurring there.[...]"

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Interesting to compare: NGC 3384 versus Messer 105...


It might appear featureless and unexciting at first glance, but NASA/ESA Hubble Space Telescope observations of this elliptical galaxy — known as Messier 105 — show that the stars near the galaxy’s centre are moving very rapidly. Astronomers have concluded that these stars are zooming around a supermassive black hole with an estimated mass of 200 million Suns! This black hole releases huge amounts of energy as it consumes matter falling into it and causing the centre to shine far brighter than its surroundings. This system is known as an active galactic nucleus.

Hubble also surprised astronomers by revealing a few young stars and clusters in Messer 105, which was thought to be a “dead” galaxy incapable of star formation. Messier 105 is now thought to form roughly one Sun-like star every 10 000 years. Star-forming activity has also been spotted in a vast ring of hydrogen gas encircling both Messier 105 and its closest neighbour, the lenticular galaxy NGC 3384."

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Tue Feb 20, 2024 10:13 pm

AVAO wrote: Wed Feb 14, 2024 9:02 pm 08.02.2024 I HST: Galaxy AM 1054-325 - Hubble detects celestial 'string of pearls' star clusters in galaxy collisions
NASA/ESA | Original release 2024 Feb 09
When spectacular cosmic events such as galaxy collisions occur, it sets off a reaction to form new stars, and possibly new planets that otherwise would not have formed. The gravitational pull that forces the collisions between these galaxies creates tidal tails—the long thin region of stars and interstellar gas. ... Specifically, NASA's Hubble Space Telescope has homed in on 12 interacting galaxies that have long, tadpole-like tidal tails of gas, dust and a plethora of stars. Hubble's exquisite sharpness and sensitivity to ultraviolet light have uncovered 425 clusters of newborn stars along these tails, looking like strings of holiday lights.

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My version with the colors of Legacy Surveys DR10:
Original Data: NASA / ESA (HST) colors from LS DR10 jac berne (flickr)

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Tue Feb 20, 2024 10:18 pm

14.02.2024 I HST: Hubble captures interacting galaxies NGC 5410 and UGC 8932
pys.org | Original release 2024 Jan 29
"A pair of small, interacting galaxies shine in this new NASA Hubble Space Telescope image. [...] The pair lies 180 million light-years away in the Canes Venatici constellation and can be seen from the northern hemisphere. Between the two galaxies lies a stream of stars, almost like a bridge, caused by their interaction. Hubble imaged this galaxy in 2023 to examine if interactions between dwarf galaxies create reservoirs of particles that fuel star formation.

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Tue Feb 20, 2024 10:25 pm

20.02.2024 I HST: IC 3476 - A high amount of ram
NASA/esa | Original release 2024 Feb 19
"This image features IC 3476, a dwarf galaxy that lies about 54 million light-years from Earth in the constellation Coma Berenices. Whilst this image does not look very dramatic — if we were to anthropomorphise the galaxy, we might say it looks almost serene — the actual physical events taking place in IC 3476 are highly energetic. In fact, the little galaxy is undergoing a process known as ram pressure stripping, which is driving unusually high levels of star formation within regions of the galaxy itself.

We tend to associate the letters ‘ram’ with the acronym RAM, which refers to Random Access Memory in computing. However, ram pressure has a totally distinct definition in physics: it is the pressure exerted on a body when it moves through some form of fluid, due to the overall resistance of the fluid. In the case of entire galaxies experiencing ram pressure, the galaxies are the ‘bodies’ and the intergalactic or intracluster medium (the dust and gas that permeates the space between galaxies, and for the latter the spaces between galaxies in clusters) is the ‘fluid’. ...


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Re: GOTD: Galaxy Of The Day

Post by AVAO » Mon Mar 04, 2024 7:48 pm

HST: A matter of perspective
NASA/ESA | 2024 March 4

Here we see NGC 4423, a galaxy that lies about 55 million light-years away in the constellation Virgo. In this image NGC 4423 appears to have quite an irregular, tubular form, so it might be surprising to find out that it is in fact a spiral galaxy. Knowing this, we can make out the denser central bulge of the galaxy, and the less crowded surrounding disc (the part that comprises the spiral arms).
...

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Mon Mar 11, 2024 9:03 pm

11.03.2024 I HST: An unlikely spiral
NASA/ESA | 2024 March 11

This image shows LEDA 42160, a galaxy about 52 million light-years from Earth in the constellation Virgo. The dwarf galaxy is one of many forcing its way through the comparatively dense gas in the Virgo cluster, a massive cluster of galaxies. The pressure exerted by this intergalactic gas, known as ram pressure, has dramatic effects on star formation in LEDA 42160, which are presently being studied using the Hubble Space Telescope.

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Wed Mar 13, 2024 9:00 pm

AVAO wrote: Sun Jan 28, 2024 7:23 pm Hubble Sees an Epic Merger of Three Galaxies
www.universetoday.com | Original release 2024 March 01
When is 50,000 light-years only a small distance? When three galaxies are that close to one another. At that range, they’re fiercely interacting. In the case of the three galaxies referred to as SDSSCGB 10189, they’re 50,000 light-years apart and growing closer as they merge into a single massive galaxy.
...
A spectacular trio of merging galaxies in the constellation Boötes takes center stage in this image from the NASA/ESA Hubble Space Telescope. These three galaxies are set on a collision course and will eventually merge into a single larger galaxy, distorting one another’s spiral structure through mutual gravitational interaction in the process. An unrelated foreground galaxy appears to float serenely near this scene, and the smudged shapes of much more distant galaxies are visible in the background.

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Re: GOTD: Galaxy Of The Day

Post by AVAO » Mon Mar 18, 2024 7:47 pm

18.03.2024 HST: The Spider (and not its web)
NASA/ESA | Original release 2024 March 18
This gauzy-looking celestial body is UGC 5829, an irregular galaxy that lies about 30 million light-years away. Despite there not being many observations of this relatively faint galaxy, it has the distinction of having a descriptive soubriquet: the Spider Galaxy. Perhaps the distorted galactic arms with their glowing, star-forming tips bring to mind the clawed legs of an arachnid. Somewhat confusingly, there is another, very similarly nicknamed but otherwise entirely distinct, galaxy known as the Spiderweb Galaxy. This galaxy has also been more extensively imaged (notably by Hubble), despite the fact that it lies about 300 times further from Earth than the Spider Galaxy does.
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Re: GOTD: Galaxy Of The Day

Post by Ann » Tue Mar 19, 2024 7:12 am

AVAO wrote: Mon Mar 18, 2024 7:47 pm 18.03.2024 HST: The Spider (and not its web)
NASA/ESA | Original release 2024 March 18
This gauzy-looking celestial body is UGC 5829, an irregular galaxy that lies about 30 million light-years away. Despite there not being many observations of this relatively faint galaxy, it has the distinction of having a descriptive soubriquet: the Spider Galaxy. Perhaps the distorted galactic arms with their glowing, star-forming tips bring to mind the clawed legs of an arachnid. Somewhat confusingly, there is another, very similarly nicknamed but otherwise entirely distinct, galaxy known as the Spiderweb Galaxy. This galaxy has also been more extensively imaged (notably by Hubble), despite the fact that it lies about 300 times further from Earth than the Spider Galaxy does.
[...]

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I think it looks amazing! :D The colors are stunning, and the galaxy is so delicate and transparent. A spider, my foot! Well, I love it when Hubble takes images of nearby galaxies, so that the pictures are so highly resolved.

ESA/Hubble wrote:

An irregular galaxy, consisting of a large central body of dull-coloured stars, with distorted arms around it.
Yes, dull-colored is the right way to describe them! But why are they so dull? Are these stars strange in some way?

No, they are ordinary yellow to yellow-orange stars, most of them tiny little red dwarfs, and some of them red giants like Pollux or Arcturus. So why do they collectively look "dull"? It's because there are so relatively few of them! UG 5829 is a low-mass galaxy, and we can tell because its yellow population is so faint! Most of the baryonic ("ordinary") mass of a galaxy is always tied up in its yellow population, and that's because the red and yellow stars produce little light for their mass.


What UGC 5829 lacks, as you can see, is a bright yellow center. On the other hand it's so full of pink and blue baubles and glitter that it resembles a (perhaps toppling) galactic Christmas tree!I

I love all the background galaxies, too. These background galaxies are typically much redder in overall color than UGC 5829, because they have been redshift-reddened by the expansion of the Universe. But sometimes I find the degree of reddening confusing.

Look at these two background galaxies:

Background of UGC 5829 ESA Hubble NASA R Tully M Messa.png

The two background galaxies appear to be the same size, shape and orientation. My immediate impression is that both are approximately the same distance from us, yet one is yellow-white and the other is red.

I find it confusing! :?


Another source of confusion is the possible mix-up between the Spider Galaxy (UGC 5829) and the Spiderweb galaxy (LEDA 2826829, MRC 1138-262).

ESA/Hubble wrote:

Somewhat confusingly, there is another, very similarly nicknamed but otherwise entirely distinct, galaxy known as the Spiderweb Galaxy. This galaxy has also been more extensively imaged (notably by Hubble), despite the fact that it lies about 300 times further from Earth than the Spider Galaxy does.
Hmm, 300 times further from the Earth than the Spider Galaxy does (whose distance is 30 million light-years). So how far away is the Spiderweb Galaxy? 30 times 300, is that 90 billion? As in, 90 billion light-years? Whoa, hold your horses, Ann! The entire observable Universe is supposed to be 90 billion light-years in diameter, so you'd better make that 9 billion light-years!


And, in case you're interested in the Spiderweb Galaxy...
ESA/Hubble wrote:

This image is a composite of many separate exposures made by the ACS instrument on the Hubble Space Telescope using several different filters. It shows the Spiderweb Galaxy sitting at the centre of an emergent galaxy cluster, surrounded by hundreds of other galaxies from the cluster.

The image provides a dramatic glimpse of a large massive galaxy under assembly as smaller galaxies merge. This has commonly been thought to be the way galaxies grew in the young Universe, but now the Hubble observations of the radio galaxy MRC 1138-262, nicknamed the "Spiderweb Galaxy", have shown dozens of star-forming satellite galaxies in the actual process of merging.
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Re: GOTD: Galaxy Of The Day

Post by AVAO » Wed Mar 20, 2024 6:54 am

Ann wrote: Tue Mar 19, 2024 7:12 am
AVAO wrote: Mon Mar 18, 2024 7:47 pm 18.03.2024 HST: The Spider (and not its web)
NASA/ESA | Original release 2024 March 18
This gauzy-looking celestial body is UGC 5829, an irregular galaxy that lies about 30 million light-years away. Despite there not being many observations of this relatively faint galaxy, it has the distinction of having a descriptive soubriquet: the Spider Galaxy. Perhaps the distorted galactic arms with their glowing, star-forming tips bring to mind the clawed legs of an arachnid. Somewhat confusingly, there is another, very similarly nicknamed but otherwise entirely distinct, galaxy known as the Spiderweb Galaxy. This galaxy has also been more extensively imaged (notably by Hubble), despite the fact that it lies about 300 times further from Earth than the Spider Galaxy does.
[...]

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I think it looks amazing! :D The colors are stunning, and the galaxy is so delicate and transparent. A spider, my foot! Well, I love it when Hubble takes images of nearby galaxies, so that the pictures are so highly resolved.

ESA/Hubble wrote:

An irregular galaxy, consisting of a large central body of dull-coloured stars, with distorted arms around it.
Yes, dull-colored is the right way to describe them! But why are they so dull? Are these stars strange in some way?

No, they are ordinary yellow to yellow-orange stars, most of them tiny little red dwarfs, and some of them red giants like Pollux or Arcturus. So why do they collectively look "dull"? It's because there are so relatively few of them! UG 5829 is a low-mass galaxy, and we can tell because its yellow population is so faint! Most of the baryonic ("ordinary") mass of a galaxy is always tied up in its yellow population, and that's because the red and yellow stars produce little light for their mass.


What UGC 5829 lacks, as you can see, is a bright yellow center. On the other hand it's so full of pink and blue baubles and glitter that it resembles a (perhaps toppling) galactic Christmas tree!I

I love all the background galaxies, too. These background galaxies are typically much redder in overall color than UGC 5829, because they have been redshift-reddened by the expansion of the Universe. But sometimes I find the degree of reddening confusing.

Look at these two background galaxies:


Background of UGC 5829 ESA Hubble NASA R Tully M Messa.png


The two background galaxies appear to be the same size, shape and orientation. My immediate impression is that both are approximately the same distance from us, yet one is yellow-white and the other is red.

I find it confusing! :?


Another source of confusion is the possible mix-up between the Spider Galaxy (UGC 5829) and the Spiderweb galaxy (LEDA 2826829, MRC 1138-262).

ESA/Hubble wrote:

Somewhat confusingly, there is another, very similarly nicknamed but otherwise entirely distinct, galaxy known as the Spiderweb Galaxy. This galaxy has also been more extensively imaged (notably by Hubble), despite the fact that it lies about 300 times further from Earth than the Spider Galaxy does.
Hmm, 300 times further from the Earth than the Spider Galaxy does (whose distance is 30 million light-years). So how far away is the Spiderweb Galaxy? 30 times 300, is that 90 billion? As in, 90 billion light-years? Whoa, hold your horses, Ann! The entire observable Universe is supposed to be 90 billion light-years in diameter, so you'd better make that 9 billion light-years!


And, in case you're interested in the Spiderweb Galaxy...
ESA/Hubble wrote:

This image is a composite of many separate exposures made by the ACS instrument on the Hubble Space Telescope using several different filters. It shows the Spiderweb Galaxy sitting at the centre of an emergent galaxy cluster, surrounded by hundreds of other galaxies from the cluster.

The image provides a dramatic glimpse of a large massive galaxy under assembly as smaller galaxies merge. This has commonly been thought to be the way galaxies grew in the young Universe, but now the Hubble observations of the radio galaxy MRC 1138-262, nicknamed the "Spiderweb Galaxy", have shown dozens of star-forming satellite galaxies in the actual process of merging.
Ann

ThanX Ann

...for your wonderful comments and suggestions.

What is interesting to me is that the Hubble image only shows a section, but the galaxy is larger.
Actually, to me this looks more than a merger of three arachnids - definitely very unusual.

As far as the colors of the background galaxies are concerned, I could imagine that an IR wavelength from the HST was used to brighten them up, so that the colors are only partially representative.

Jac

Click to view full size image 1 or image 2

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Ann
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Re: GOTD: Galaxy Of The Day

Post by Ann » Wed Mar 20, 2024 8:13 am

AVAO wrote: Wed Mar 20, 2024 6:54 am
ThanX Ann

...for your wonderful comments and suggestions.

What is interesting to me is that the Hubble image only shows a section, but the galaxy is larger.
Actually, to me this looks more than a merger of three arachnids - definitely very unusual.

As far as the colors of the background galaxies are concerned, I could imagine that an IR wavelength from the HST was used to brighten them up, so that the colors are only partially representative.

Jac

Click to view full size image 1 or image 2

And thank you, Jac, for once again showing me more of the galaxy in question than Hubble would show me! :D

Ann
Color Commentator