APOD: Galaxies: Wild's Triplet from Hubble (2022 Nov 08)

[APOD Robot]

Galaxies: Wild's Triplet from Hubble

Explanation: How many galaxies are interacting here? This grouping of galaxies is called the Wild Triplet, not only for the discoverer, but for the number of bright galaxies that appear. It had been assumed that all three galaxies, collectively cataloged as Arp 248, are interacting, but more recent investigations reveal that only the brightest two galaxies are sparring gravitationally: the big galaxies at the top and bottom. The spiral galaxy in the middle of the featured image by the Hubble Space Telescope is actually far in the distance, as is the galaxy just below it and all of the other numerous galaxies in the field. A striking result of these giants jousting is a tremendous bridge of stars, gas, and dust that stretches between them -- a bridge almost 200,000 light-years long. Light we see today from Wild's Triplet left about 200 million years ago, when dinosaurs roamed the Earth. In perhaps a billion years or so, the two interacting galaxies will merge to form a single large spiral galaxy.

<< Previous APOD

This Day in APOD

Next APOD >>

[AVAO]

Galaxies: Wild's Triplet from Hubble

...This grouping of galaxies is called the Wild Triplet, not only for the discoverer, but for the number of bright galaxies that appear. It had been assumed that all three galaxies, collectively cataloged as Arp 248, are interacting, but more recent investigations reveal that only the brightest two galaxies are sparring gravitationally: the big galaxies at the top and bottom.
...

...The description is misleading. Only two of the three galaxies are shown in today's APOD image...


http://www.caelumobservatory.com/mlsc/wilds.jpg
Credit / Copyright: Adam Block/Mount Lemmon SkyCenter/University of Arizona

[Ann]

Galaxies: Wild's Triplet from Hubble

...This grouping of galaxies is called the Wild Triplet, not only for the discoverer, but for the number of bright galaxies that appear. It had been assumed that all three galaxies, collectively cataloged as Arp 248, are interacting, but more recent investigations reveal that only the brightest two galaxies are sparring gravitationally: the big galaxies at the top and bottom.
...

...The description is misleading. Only two of the three galaxies are shown in today's APOD image...


http://www.caelumobservatory.com/mlsc/wilds.jpg
Credit / Copyright: Adam Block/Mount Lemmon SkyCenter/University of Arizona

Wow, thanks a billion, AVAO! I would have missed that completely!

Ann

[daddyo]

The galaxy at image center seems to have a smaller galaxy punching through it, maybe creating the arms on the former

[Ann]

Anyway, let's return to the APOD!

Two of the three galaxies of Wild's Triplet and the long bridge between them. Image Credit: ESA/Hubble, NASA, Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA, J. Dalcanton

---

The long tail of UGC 10214, the Tadpole Galaxy. Credit: NASA, H. Ford (JHU), G. Illingworth (USCS/LO), M. Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA.

---

The long bridge between two of the three galaxies of Wild's Triplet reminds me of the long tail of the Tadpole galaxy. In both cases, the tail or bridge contains bright blue star clusters, which in time may evolve into dwarf galaxies.


In pictures like these, I love looking at the background galaxies and trying to figure out what sort of galaxies they are and how distant they are compared with the main galaxy (or galaxies) in the picture. Take a look at a part of the picture of the Tadpole galaxy, where I, from my amateur perspective, have assigned relative distances to some of the galaxies:

Background and satellite galaxies of the Tadpole galaxy
and star clusters in the Tadpole's tail.

NGC 1559, similar to the galaxy that I have labeled 'Relatively nearby highly starforming background galaxy'? Credit: ESO.

---

NGC 7606, a large spiral galaxy possibly similar to the yellow-looking spirals that I labeled as more distant spiral background galaxies of the Tadpole. Image: SDSS.

---

NGC 205, small elliptical satellite galaxy of Andromeda. It may be similar to the galaxy that I have labeled 'Dwarf spheroidal satellite galaxy of the Tadpole'. Credit: Noao/aura/nsf.

---

I looked at a part of today's APOD too, to try to describe some satellite galaxies:

So there is one rather faint galaxy, which I believe to be either a nearby small background galaxy, or else an actual satellite galaxy of Wild's Triplet. The bright large galaxy with a yellow-orange center and a large blue-rimmed disk (or two blue spiral arms) is clearly an intrinsically large and bright background galaxy. The small-looking spiral galaxy that I have labeled "Possible satellite galaxy of the large background galaxy" could actually be an even more distant and quiet large spiral galaxy.

Oh well! I have absolutely no time to write more here now, so I'm off!

Ann

[beryllium732]

Would there be any sunlike stars in that tail? I do see a lot of blue stars. Imagine the view if the solar system would be in that location. The galaxies would take up a big chunk of the night sky.

[Chris Peterson]

Would there be any sunlike stars in that tail? I do see a lot of blue stars. Imagine the view if the solar system would be in that location. The galaxies would take up a big chunk of the night sky.

There are many sun-like stars there. And the view might be less impressive than you'd think. Basically, it would look the same as the Milky Way looks to us, just shaped somewhat different.

[orin stepanek]

Three in the Triplet; yes but there are many in the photo!
https://i.insider.com/55a67a7a371d22ce178b6624
Smart Kitty!

[Bird_Man]

I wonder what the night sky would look like from a planet around one of the starts in the "bridge" compared to being around a star within the galaxy?

[Chris Peterson]

I wonder what the night sky would look like from a planet around one of the starts in the "bridge" compared to being around a star within the galaxy?

The bridge is likely not visible to the eye. Inside a galaxy you'd see something like the Milky Way, with the other galaxy something like one of the Magellanic Clouds. From the bridge you'd see something like a pair of Magellanic Clouds (but somewhat larger), or a kind of split Milky Way. I doubt the sky would be any more impressive than our own.

[VictorBorun]

I see three "Red/blue galaxy" objects here; I labeled them 3 5 6
There is a "violet galaxy" objects here; I labeled it 1
There is a "white/blue galaxy" objects here; I labeled its place 2 (see the left side)
There are a "white/orange galaxy" objects here; I labeled their places 2 (see the right side) and 4

To my eye there seem to be 3 rings left from the 5"Red/blue galaxy" object 6,
of brown, white and pink colour
of the same size and angle to our line of sight
of different spin orientation: 60°, 45°, 30°west in this picture frame

[Ann]

I see three "Red/blue galaxy" objects here; I labeled them 3 5 6
There is a "violet galaxy" objects here; I labeled it 1
There is a "white/blue galaxy" objects here; I labeled its place 2 (see the left side)
There are a "white/orange galaxy" objects here; I labeled their places 2 (see the right side) and 4

WildTriplet_Hubble 144.jpg

To my eye there seem to be 3 rings left from the 5"Red/blue galaxy" object 6,
of brown, white and pink colour
of the same size and angle to our line of sight
of different spin orientation: 60°, 45°, 30°west in this picture frame
WildTriplet_Hubble 144 3 rings.jpg

Interesting, Victor! This is what I think:

Your #1 could possibly be some sort of semi-normal low surface brightness galaxy, where the blue patch is dominated by modest blue (Sirius-like) stars.

#2 is a very small and distant object (or possibly a multiple object), and its surface brightness is high. I think it could be a real galaxy (or a small very distant triplet of galaxies of different colors).

#3 is weird! Seriously! It doesn't look "real" to me.

#4 looks okay to me. I think it is a highly starforming, dusty galaxy. I think its shape is neither spiral nor irregular, but something in between. I think its blue patches are dust-reddened to a white color, and I think other parts of it look orange from dust.

I think #5 is two galaxies, one small red very distant elliptical(?) and one slightly less distant mostly blue edge-on disk galaxy of some sort. If it is a disk galaxy, then one half of it is making a lot more stars than the other half, but that kind of phenomenon is not unheard of. Nearby galaxy NGC 7496 is a bit like that. But if #5 is not two galaxies, but a single one, then I agree that it is totally weird!

#6 is crazy. Just saying! I don't think it is for real, but rather some sort of mistake in either data acquisition or processing.

Ann

[Lizzy]

QQ: Why is the future state of these galaxies described as a "single large spiral galaxy", instead of an elliptical? Is there something inherent in the spin, age, size, or other characteristic(s) that make astronomers confident about the resulting form of these two merged galaxies? Thanks, and I love APOD!!!

[heehaw]

Every time I look at a galaxy, I wonder how many 'people' there have looked at OUR dear galaxy. I'll never know the answer.

[johnnydeep]

Galaxies: Wild's Triplet from Hubble

...This grouping of galaxies is called the Wild Triplet, not only for the discoverer, but for the number of bright galaxies that appear. It had been assumed that all three galaxies, collectively cataloged as Arp 248, are interacting, but more recent investigations reveal that only the brightest two galaxies are sparring gravitationally: the big galaxies at the top and bottom.
...

...The description is misleading. Only two of the three galaxies are shown in today's APOD image...


http://www.caelumobservatory.com/mlsc/wilds.jpg
Credit / Copyright: Adam Block/Mount Lemmon SkyCenter/University of Arizona

I had noticed that discrepancy as well, but what's the true story here? Are the three galaxies in the image at the Wikipedia page really interacting or not? From the clear trails of stars connecting them, I would say yes. Yet this APOD implies that only two of the galaxies in the "Wild Triple" are interacting, which is clearly the actual case if the three galaxies are instead the ones in this APOD.

[Ann]

Galaxies: Wild's Triplet from Hubble

...This grouping of galaxies is called the Wild Triplet, not only for the discoverer, but for the number of bright galaxies that appear. It had been assumed that all three galaxies, collectively cataloged as Arp 248, are interacting, but more recent investigations reveal that only the brightest two galaxies are sparring gravitationally: the big galaxies at the top and bottom.
...

...The description is misleading. Only two of the three galaxies are shown in today's APOD image...


http://www.caelumobservatory.com/mlsc/wilds.jpg
Credit / Copyright: Adam Block/Mount Lemmon SkyCenter/University of Arizona

I had noticed that discrepancy as well, but what's the true story here? Are the three galaxies in the image at the Wikipedia page really interacting or not? From the clear trails of stars connecting them, I would say yes. Yet this APOD implies that only two of the galaxies in the "Wild Triple" are interacting, which is clearly the actual case if the three galaxies are instead the ones in this APOD.

Wikipedia wrote:

Wild's Triplet is a group of three small, interacting spiral galaxies. The galaxies are visible in the constellation Virgo. The triplet has luminous connecting bridges and is located some 200 million light-years away.

The Wikipedia stub is illustrated with the same Adam Block image that AVAO posted here. Clearly the background galaxy in the APOD has never been a member of Wild's Triplet.

You can tell that the two galaxies seen in the APOD are small:

NGC 1313, imaged on ATEO-3 by Franck Jobard and processed by Utkarsh Mishra from Deep Sky Chile.

---

As for this member of Wild's Triplet, note that its huge region of star formation (at lower right) is probably brighter, or at least as bright, as its center. Only low-mass galaxies can have regions of star formation brighter than their centers. Note in the picture of the low-mass, highly disturbed galaxy NGC 1313 that its pink and blue arms are brighter than its center.

The core of galaxy NGC 4314, surrounded by a ring of star formation. Credit: G. Fritz Benedict, Andrew Howell, Inger Jorgensen, David Chapell (University of Texas), Jeffery Kenney (Yale University), and Beverly J. Smith (CASA, University of Colorado), and NASA

---

The other member of Wild's Triplet imaged in the APOD appears to be a little more massive, or at least its center is a little brighter. The core is somewhat large and "abruptly brighter" than its yellow-orange surroundings, which suggests that it is encircled by a bright ring of formation, similar to what we see in galaxy NGC 4314.


To me, the two galaxies of Wild's Triplet seen in the APOD also look small because they are "coarse" and not so elegant. Let's compare them with another galaxy that is actually not very big, but I find it quite elegant:

NGC 5054. Image: Mark Hanson and Mike Selby.

Note the beautifully shaped yellow inner region of NGC 5054, with fine dust lanes winding inside it. The core may be surrounded by regions of star formation. The yellow inner disk is ring-shaped and well separated from the arms, whose inner parts are delineated by elegant thin dust lanes. The spiral arms are quite long, elegantly curved and full of regions of star formation of pink and blue. I would not be entirely surprised if the small edge-on blue galaxy at right is a satellite galaxy of NGC 5054, which interacts with the larger galaxy.

But the members of Wild's Triplet are much coarser. The stellar populations of their centers and arms are not nearly as well separated, and their dust lanes are nowhere near as thin and long. They do look small to me - and they are.

Ann

[Ann]

QQ: Why is the future state of these galaxies described as a "single large spiral galaxy", instead of an elliptical? Is there something inherent in the spin, age, size, or other characteristic(s) that make astronomers confident about the resulting form of these two merged galaxies? Thanks, and I love APOD!!!

Hi Lizzy, I hope you are reading this!

You are correct that most galaxy mergers are expected to result in elliptical galaxies. The merging of the Milky Way and Andromeda some 5 billion years from now is believed to turn our two galaxies into one super-sized elliptical.

But mergers can actually create large spirals too, even though that is much more unusual.

NASA wrote:

A strange new kind of galactic beast has been spotted in the cosmic wilderness. Dubbed "super spirals," these unprecedented galaxies dwarf our own spiral galaxy, the Milky Way, and compete in size and brightness with the largest galaxies in the universe.
...
A vital hint about the potential origin of super spirals is that four out of the 53 seen by Ogle and colleagues clearly contain two galactic nuclei, instead of just one as usual. Double nuclei, which look like two egg yolks frying in a pan, are a telltale sign of two galaxies having just merged together. Conventionally, mergers of spiral galaxies are destined to become bloated, elliptical galaxies. Yet Ogle and colleagues speculate that a special merger involving two, gas-rich spiral galaxies could see their pooled gases settle down into a new, larger stellar disk -- presto, a super spiral.

So a galactic merger can indeed create a super spiral. But if astronomers have any special reason to believe that Wild's Triplet will merge into one large spiral galaxy, I don't know!

Ann

[johnnydeep]

...The description is misleading. Only two of the three galaxies are shown in today's APOD image...


http://www.caelumobservatory.com/mlsc/wilds.jpg
Credit / Copyright: Adam Block/Mount Lemmon SkyCenter/University of Arizona

I had noticed that discrepancy as well, but what's the true story here? Are the three galaxies in the image at the Wikipedia page really interacting or not? From the clear trails of stars connecting them, I would say yes. Yet this APOD implies that only two of the galaxies in the "Wild Triple" are interacting, which is clearly the actual case if the three galaxies are instead the ones in this APOD.

Wikipedia wrote:

Wild's Triplet is a group of three small, interacting spiral galaxies. The galaxies are visible in the constellation Virgo. The triplet has luminous connecting bridges and is located some 200 million light-years away.

...
But the members of Wild's Triplet are much coarser. The stellar populations of their centers and arms are not nearly as well separated, and their dust lanes are nowhere near as thin and long. They do look small to me - and they are.

Ann

So, not to beat a dead horse here, but this APOD is seriously flawed: the image used only shows 2 of the 3 true members of the Wild Triple, and the text is also wrong in implying that only 2 of the - true - members of the triple are actually interacting. In reality all 3 are.

[Ann]

So, not to beat a dead horse here, but this APOD is seriously flawed: the image used only shows 2 of the 3 true members of the Wild Triple, and the text is also wrong in implying that only 2 of the - true - members of the triple are actually interacting. In reality all 3 are.

I guess that's because Hubble has such a small field of view that all three members of Wild's Triplet wouldn't fit into a single "pointing" of Hubble, and the demand for observation time on this telescope is so high, that NASA decided that Hubble wouldn't be allowed to observe more than two of the three members of Wild's Triplet.

Of course, NASA should have said clearly and in public that one member of Wild's Triplet was missing from their image.

Ann

[johnnydeep]

So, not to beat a dead horse here, but this APOD is seriously flawed: the image used only shows 2 of the 3 true members of the Wild Triple, and the text is also wrong in implying that only 2 of the - true - members of the triple are actually interacting. In reality all 3 are.

I guess that's because Hubble has such a small field of view that all three members of Wild's Triplet wouldn't fit into a single "pointing" of Hubble, and the demand for observation time on this telescope is so high, that NASA decided that Hubble wouldn't be allowed to observe more than two of the three members of Wild's Triplet.

Of course, NASA should have said clearly and in public that one member of Wild's Triplet was missing from their image.

Ann

Hmm. I didn't realize that NASA has the same bad info at https://science.nasa.gov/galaxies-wilds-triplet-hubble, which links to this APOD. And in fact, it uses the exact same text. At least the APOD text could be corrected, if not the text at science.nasa.gov. Are the same people responsible for both sites?

[Chris Peterson]

So, not to beat a dead horse here, but this APOD is seriously flawed: the image used only shows 2 of the 3 true members of the Wild Triple, and the text is also wrong in implying that only 2 of the - true - members of the triple are actually interacting. In reality all 3 are.

I guess that's because Hubble has such a small field of view that all three members of Wild's Triplet wouldn't fit into a single "pointing" of Hubble, and the demand for observation time on this telescope is so high, that NASA decided that Hubble wouldn't be allowed to observe more than two of the three members of Wild's Triplet.

Of course, NASA should have said clearly and in public that one member of Wild's Triplet was missing from their image.

Ann

Hmm. I didn't realize that NASA has the same bad info at https://science.nasa.gov/galaxies-wilds-triplet-hubble, which links to this APOD. And in fact, it uses the exact same text. At least the APOD text could be corrected, if not the text at science.nasa.gov. Are the same people responsible for both sites?

No. But the APOD captions frequently borrow heavily from the captions on sites where images originate. The ESA page for this image does a lot better job: https://esahubble.org/images/potw2244a/

[starsurfer]

Makes me think of this song:

Click to play embedded YouTube video.