APOD: The Leo Trio (2021 Mar 20)

[APOD Robot]

The Leo Trio

Explanation: This popular group leaps into the early evening sky around the March equinox and the northern hemisphere spring. Famous as the Leo Triplet, the three magnificent galaxies found in the prominent constellation Leo gather here in one astronomical field of view. Crowd pleasers when imaged with even modest telescopes, they can be introduced individually as NGC 3628 (right), M66 (upper left), and M65 (bottom). All three are large spiral galaxies but tend to look dissimilar, because their galactic disks are tilted at different angles to our line of sight. NGC 3628, also known as the Hamburger Galaxy, is temptingly seen edge-on, with obscuring dust lanes cutting across its puffy galactic plane. The disks of M66 and M65 are both inclined enough to show off their spiral structure. Gravitational interactions between galaxies in the group have left telltale signs, including the tidal tails and warped, inflated disk of NGC 3628 and the drawn out spiral arms of M66. This gorgeous view of the region spans over 1 degree (two full moons) on the sky in a frame that covers over half a million light-years at the trio's estimated distance of 30 million light-years. Of course the spiky foreground stars lie well within our own Milky Way.

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[Ann]

The Leo Trio. M66 is at upper left, M65 is at lower left, and NGC 3628 is at right. Photo: Francis Bozon.

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I really, really like this APOD! Because it does a great job of capturing the distinguishing features of the three galaxies in the Leo Trio, M65, M66 and NGC 3628, in a single image!

M66. Credits: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration; Acknowledgment: Davide De Martin and Robert Gendler

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M65 with supernova SN 2013am. Photo: Bill Williams.

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In the Hubble closeup of M66 at left, you can see that M66 contains a good number of young blue star clusters and also red emission nebulas where new stars are being born. M66 is both red and blue.

But where are the young blue stars in M65? Well, take a look at the picture at right. The arrow points at supernova 2013am, which, fascinatingly, was a type II supernova, a massive star undergoing core collapse. But M65 looks all smooth and reddish, doesn't it? Surely there can't be many massive young blue stars in that galaxy?

Well, look again. Can you see a faint bluish patch to the upper left of the supernova? That's a young bluish star cluster. And there are some even fainter star clusters to the left of the brightest blue patch.

My point is that there are some young stars in M65, but they are very few indeed. And one of them exploded as a supernova that we could see in 2013. But overall, M65 is a red galaxy.

M65 (top) and M66. Photo: Joseph M. Drudis.

The amazing tail of NGC 3628. Photo: Mark Hanson.

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And you must also look at a great picture of M65 and M66 by Jospeh M Drudis, which shows the "puffiness" of M66 compared with M65, and a fantastic portrait of the tail of NGC 3628 by Mark Hanson. Go to this site and see how Mark Hanson highlights possible dwarf galaxies that may have formed in the tail.

To summarize, and to return to today's APOD:

In a single image, Francis Bozon captured the "red and blue puffiness" of M66, the undisturbed red ellipsoid of M65, and the puffed-up disk ends and tail of NGC 3628.

That's most certainly not bad!

Ann

[VictorBorun]

In a single image, Francis Bozon captured the "red and blue puffiness" of M66, the undisturbed red ellipsoid of M65, and the puffed-up disk ends and tail of NGC 3628.
Ann

Can the two disks be parallel planes?

1) Judging by visual elliptic form and backlighted dust near cores, the two look like dishes on two shelves before and below the observer. At the distance of d the shelves must be below the observer by h=d*r_short/r_long,
for Messier 65 r_short/r_long= 2.454/8.709, d=? Let's take the mean distance of M66 & NGC 3628, 33 Mly. Then h=9.3 Mly
for Messier 66 r_short/r_long=4.2/9.1, d=31 Mly, h=14.3 Mly
That's 14.3-9.3 = 5 Mly between the shelves.
Is it probable?

2) Some suggest that planes of galaxy disks can correlate at great distances. That quasar jets tend to align with cosmologic strings of galaxy clusters.

[orin stepanek]

Today's AOPD; I like It!

[sillyworm 2]

NGC 3628's tail.Once drawn out..do the stars rotate around the center of the galaxy at the same speed as the stars in the original spiral? Do the stars continue to move outward? Do they start to lag behind and eventually join the spiral structure?

[Ann]

In a single image, Francis Bozon captured the "red and blue puffiness" of M66, the undisturbed red ellipsoid of M65, and the puffed-up disk ends and tail of NGC 3628.
Ann

Can the two disks be parallel planes?

1) Judging by visual elliptic form and backlighted dust near cores, the two look like dishes on two shelves before and below the observer. At the distance of d the shelves must be below the observer by h=d*r_short/r_long,
for Messier 65 r_short/r_long= 2.454/8.709, d=? Let's take the mean distance of M66 & NGC 3628, 33 Mly. Then h=9.3 Mly
for Messier 66 r_short/r_long=4.2/9.1, d=31 Mly, h=14.3 Mly
That's 14.3-9.3 = 5 Mly between the shelves.
Is it probable?

2) Some suggest that planes of galaxy disks can correlate at great distances. That quasar jets tend to align with cosmologic strings of galaxy clusters.

Bear with me, Victor, because I'm a math idiot, and there is too much math-speak in your post.

But I think you are asking if the distance between M65 and M66 might be 5 million light years. According to Rob Gendler, the distance between these two galaxies is much smaller, 160,000 light years.

http://www.robgendlerastropics.com/LeoTriplettext.html

Can we be absolutely sure that Rob Gendler's information is correct? I can't be the judge of that, but in my opinion you can actually see that the Leo Trio is a tight group. If we assume, for the sake of the argument, that the size of the visible disks of these galaxies (excluding the tail of NGC 3628) is 100,000 light-years, then it becomes obvious that the distance between them just can't be as much as 5 million light-years.

160,000 ly seems a lot more reasonable, particularly if the disks of these galaxies are a bit smaller than 100,000 ly.

Ann

[johnnydeep]

The Leo Trio

Explanation: This popular group leaps into the early evening sky around the March equinox and the northern hemisphere spring. Famous as the Leo Triplet, the three magnificent galaxies found in the prominent constellation Leo gather here in one astronomical field of view. Crowd pleasers when imaged with even modest telescopes, they can be introduced individually as NGC 3628 (right), M66 (upper left), and M65 (bottom). All three are large spiral galaxies but tend to look dissimilar, because their galactic disks are tilted at different angles to our line of sight. NGC 3628, also known as the Hamburger Galaxy, is temptingly seen edge-on, with obscuring dust lanes cutting across its puffy galactic plane. The disks of M66 and M65 are both inclined enough to show off their spiral structure. Gravitational interactions between galaxies in the group have left telltale signs, including the tidal tails and warped, inflated disk of NGC 3628 and the drawn out spiral arms of M66. This gorgeous view of the region spans over 1 degree (two full moons) on the sky in a frame that covers over half a million light-years at the trio's estimated distance of 30 million light-years. Of course the spiky foreground stars lie well within our own Milky Way.

Two minor issues:

1. The second pic at the link to "everything you need to know about the equinox" makes no sense to me. What is it depicting? Sure, the (red!) sun at every hour, but what are the strange whitish ovoid areas? Are those supposed to be sheared off mountain tops? This image does little to add to the explanation IMHO.

The day arc of the sun, every hour, at the equinox, as seen on the (imaginary) celestial sphere surrounding Earth. At the equinox, the sun is directly above Earth’s equator. Image via Tau’olunga/ Wikimedia Commons

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2. The link to M66 - http://heritage.stsci.edu/2010/02/caption.html - seems to be obsolete. Using the search at heritage.stsci.edu (which redirects to https://hubblesite.org/resource-gallery ... e-heritage) for M66 returned no hits.

[johnnydeep]

In a single image, Francis Bozon captured the "red and blue puffiness" of M66, the undisturbed red ellipsoid of M65, and the puffed-up disk ends and tail of NGC 3628.
Ann

Can the two disks be parallel planes?

1) Judging by visual elliptic form and backlighted dust near cores, the two look like dishes on two shelves before and below the observer. At the distance of d the shelves must be below the observer by h=d*r_short/r_long,
for Messier 65 r_short/r_long= 2.454/8.709, d=? Let's take the mean distance of M66 & NGC 3628, 33 Mly. Then h=9.3 Mly
for Messier 66 r_short/r_long=4.2/9.1, d=31 Mly, h=14.3 Mly
That's 14.3-9.3 = 5 Mly between the shelves.
Is it probable?

2) Some suggest that planes of galaxy disks can correlate at great distances. That quasar jets tend to align with cosmologic strings of galaxy clusters.

Are what two disks parallel? M65 and M66? Based on the fact that both are about 35 Mly distant, and their close angular separation in the sky as seen from Earth (less than 1 degree), and the fact that they don't look at all parallel from our pov, I'd say there's no way their two disk are parallel. NGC 3628 is also about 35 Mly and so the same can be said for its disk in comparison to M65 and M66.

[Chris Peterson]

The Leo Trio

Explanation: This popular group leaps into the early evening sky around the March equinox and the northern hemisphere spring. Famous as the Leo Triplet, the three magnificent galaxies found in the prominent constellation Leo gather here in one astronomical field of view. Crowd pleasers when imaged with even modest telescopes, they can be introduced individually as NGC 3628 (right), M66 (upper left), and M65 (bottom). All three are large spiral galaxies but tend to look dissimilar, because their galactic disks are tilted at different angles to our line of sight. NGC 3628, also known as the Hamburger Galaxy, is temptingly seen edge-on, with obscuring dust lanes cutting across its puffy galactic plane. The disks of M66 and M65 are both inclined enough to show off their spiral structure. Gravitational interactions between galaxies in the group have left telltale signs, including the tidal tails and warped, inflated disk of NGC 3628 and the drawn out spiral arms of M66. This gorgeous view of the region spans over 1 degree (two full moons) on the sky in a frame that covers over half a million light-years at the trio's estimated distance of 30 million light-years. Of course the spiky foreground stars lie well within our own Milky Way.

Two minor issues:

1. The second pic at the link to "everything you need to know about the equinox" makes no sense to me. What is it depicting? Sure, the (red!) sun at every hour, but what are the strange whitish ovoid areas? Are those supposed to be sheared off mountain tops? This image does little to add to the explanation IMHO.

It's a bit out of context by itself. If you look at the Wikipedia Equinox page you'll see that this is one of five related images, showing the Sun arc at different latitudes. Each image features a little island in the center with a tree characteristic of the latitude. This image is the Sun arc at the north pole. So the little island in the middle is the top of an iceberg.

[sillyworm 2]

Would someone please answer my questions? Thanks

[Chris Peterson]

NGC 3628's tail.Once drawn out..do the stars rotate around the center of the galaxy at the same speed as the stars in the original spiral? Do the stars continue to move outward? Do they start to lag behind and eventually join the spiral structure?

The stars have been perturbed into new orbits. They may not even be in elliptical orbits anymore, but in hyperbolic ones, meaning they are no longer gravitational bound to their parent galaxy. Or, they could be in new elliptical orbits around the overall cluster. There is no way of knowing without making careful measurements of the stellar velocities, which may not be possible with our current technology.

[johnnydeep]

The Leo Trio

Explanation: This popular group leaps into the early evening sky around the March equinox and the northern hemisphere spring. Famous as the Leo Triplet, the three magnificent galaxies found in the prominent constellation Leo gather here in one astronomical field of view. Crowd pleasers when imaged with even modest telescopes, they can be introduced individually as NGC 3628 (right), M66 (upper left), and M65 (bottom). All three are large spiral galaxies but tend to look dissimilar, because their galactic disks are tilted at different angles to our line of sight. NGC 3628, also known as the Hamburger Galaxy, is temptingly seen edge-on, with obscuring dust lanes cutting across its puffy galactic plane. The disks of M66 and M65 are both inclined enough to show off their spiral structure. Gravitational interactions between galaxies in the group have left telltale signs, including the tidal tails and warped, inflated disk of NGC 3628 and the drawn out spiral arms of M66. This gorgeous view of the region spans over 1 degree (two full moons) on the sky in a frame that covers over half a million light-years at the trio's estimated distance of 30 million light-years. Of course the spiky foreground stars lie well within our own Milky Way.

Two minor issues:

1. The second pic at the link to "everything you need to know about the equinox" makes no sense to me. What is it depicting? Sure, the (red!) sun at every hour, but what are the strange whitish ovoid areas? Are those supposed to be sheared off mountain tops? This image does little to add to the explanation IMHO.

It's a bit out of context by itself. If you look at the Wikipedia Equinox page you'll see that this is one of five related images, showing the Sun arc at different latitudes. Each image features a little island in the center with a tree characteristic of the latitude. This image is the Sun arc at the north pole. So the little island in the middle is the top of an iceberg.

Thanks, that helps! So it seems the red suns indicate where it is at the observer's horizon, aka a "twilight sun" per the caption. As for those mountain tops being icebergs, the other pics show a tree growing on one of them!

The day arc of the Sun, every hour, during the equinoxes as seen on the celestial dome, from 50° latitude. Also showing 'twilight suns' down to -18° altitude.

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[hypatia]

Am I the only one who thinks 3628 looks like the Eiffel Tower?

[VictorBorun]

In a single image, Francis Bozon captured the "red and blue puffiness" of M66, the undisturbed red ellipsoid of M65, and the puffed-up disk ends and tail of NGC 3628.
Ann

Can the two disks be parallel planes?

1) Judging by visual elliptic form and backlighted dust near cores, the two look like dishes on two shelves before and below the observer. At the distance of d the shelves must be below the observer by h=d*r_short/r_long,
for Messier 65 r_short/r_long= 2.454/8.709, d=? Let's take the mean distance of M66 & NGC 3628, 33 Mly. Then h=9.3 Mly
for Messier 66 r_short/r_long=4.2/9.1, d=31 Mly, h=14.3 Mly
That's 14.3-9.3 = 5 Mly between the shelves.
Is it probable?

2) Some suggest that planes of galaxy disks can correlate at great distances. That quasar jets tend to align with cosmologic strings of galaxy clusters.

Are what two disks parallel? M65 and M66? Based on the fact that both are about 35 Mly distant, and their close angular separation in the sky as seen from Earth (less than 1 degree), and the fact that they don't look at all parallel from our pov, I'd say there's no way their two disk are parallel. NGC 3628 is also about 35 Mly and so the same can be said for its disk in comparison to M65 and M66.

1° at 35 Mly is 0.6 Mly, and my 5 Mly are 8 times greater than that.
Ok. The planes of M65 and M66 are not parallel.

As for NGC 3628, is a tail a telltale sign of ramming into the cluster ? Then NGC 3628 would had been born somewhere else and had no reason to align its plane in the first place.

[VictorBorun]

Am I the only one who thinks 3628 looks like the Eiffel Tower?

Can the wide part at the bottom be dust in an arm, reaching up an toward us and backlighted by the stellar disk?
Then the other arm should be all but invisible to us, making for a little top of the Eiffel Tower before going invisible behind the frontlight.

[johnnydeep]

Can the two disks be parallel planes?

1) Judging by visual elliptic form and backlighted dust near cores, the two look like dishes on two shelves before and below the observer. At the distance of d the shelves must be below the observer by h=d*r_short/r_long,
for Messier 65 r_short/r_long= 2.454/8.709, d=? Let's take the mean distance of M66 & NGC 3628, 33 Mly. Then h=9.3 Mly
for Messier 66 r_short/r_long=4.2/9.1, d=31 Mly, h=14.3 Mly
That's 14.3-9.3 = 5 Mly between the shelves.
Is it probable?

2) Some suggest that planes of galaxy disks can correlate at great distances. That quasar jets tend to align with cosmologic strings of galaxy clusters.

Are what two disks parallel? M65 and M66? Based on the fact that both are about 35 Mly distant, and their close angular separation in the sky as seen from Earth (less than 1 degree), and the fact that they don't look at all parallel from our pov, I'd say there's no way their two disk are parallel. NGC 3628 is also about 35 Mly and so the same can be said for its disk in comparison to M65 and M66.

1° at 35 Mly is 0.6 Mly, and my 5 Mly are 8 times greater than that.
Ok. The planes of M65 and M66 are not parallel.

As for NGC 3628, is a tail a telltale sign of ramming into the cluster ? Then NGC 3628 would had been born somewhere else and had no reason to align its plane in the first place.

Maybe I'm missing something, but the galactic plane of NGC 3628 does not appear to be aligned with either M65 or M66.

[VictorBorun]

As for NGC 3628, is a tail a telltale sign of ramming into the cluster ? Then NGC 3628 would had been born somewhere else and had no reason to align its plane in the first place.

Maybe I'm missing something, but the galactic plane of NGC 3628 does not appear to be aligned with either M65 or M66.

Suppose for a moment, that a cosmologic string (comphessed between 3 voids) is likely to form galaxy clusters with rotation axis along that string, and that main galaxies that sink down to the center of a cluster tend to rotate along the same direction. Than the gas disks should have parallel or almost parallel planes, in general.

NGC 3628 is quite perpendicular to the other two galaxies in the pic. But was it born here at all?

[sillyworm 2]

Thanks Chris I can always count on you.

[johnnydeep]

As for NGC 3628, is a tail a telltale sign of ramming into the cluster ? Then NGC 3628 would had been born somewhere else and had no reason to align its plane in the first place.

Maybe I'm missing something, but the galactic plane of NGC 3628 does not appear to be aligned with either M65 or M66.

Suppose for a moment, that a cosmologic string (comphessed between 3 voids) is likely to form galaxy clusters with rotation axis along that string, and that main galaxies that sink down to the center of a cluster tend to rotate along the same direction. Than the gas disks should have parallel or almost parallel planes, in general.

NGC 3628 is quite perpendicular to the other two galaxies in the pic. But was it born here at all?

Maybe I'm just too dumb to theorize, but without good evidence - and I don't see any - they're likely just randomly oriented.

[VictorBorun]

Suppose for a moment, that a cosmologic string (comphessed between 3 voids) is likely to form galaxy clusters with rotation axis along that string, and that main galaxies that sink down to the center of a cluster tend to rotate along the same direction. Than the gas disks should have parallel or almost parallel planes, in general.

NGC 3628 is quite perpendicular to the other two galaxies in the pic. But was it born here at all?

Maybe I'm just too dumb to theorize, but without good evidence - and I don't see any - they're likely just randomly oriented.

It's a Yes-No-Maybe So thing.

Click to view full size image

Artist’s impression of mysterious alignment of quasar rotation axes
https://www.eso.org/public/usa/images/eso1438a
https://astronomy.com/magazine/news/201 ... xies-align[/img2]