Messier 51

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Graeme
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Messier 51

Post by Graeme »

Here's Messier 51, two galaxies crashing into each other. My February attempt at it was a bit poor so I did a spring clean on the telescope and had another go.

M51 - Whirlpool Galaxy - 01-EL.jpg

I'm surprised to have captured any data at all the way the night progressed. The telescope mount and the camera are connected to the pc via USB but in order to overcome the USB 5m cable length limitation and stay in the warm, I convert the signals and transmit them over an Ethernet cable. I lost connection to the mount 4 times. Then once focused, polar aligned and plate solved, I lost the connection to the camera on the guide scope and the imaging camera refused to cool. Then once that was sorted the guiding software crashed (a new upgraded version) and I couldn't restart because it saw the first instance running. So I had to restart the pc. To do that I had to warm the imaging camera, home the telescope and disconnect everything. I uninstalled the guiding software then downloaded and installed an older stable version. After managing to get set up again and capturing 13 x 240 second sub frames the imaging camera reported a failed to retrieve data error! The final stage is always to capture a set of 30 or so images of the dust on the sensor to subtract during processing, the camera kept saving one frame and crashing, I saved 5.

I think the data conversion I'm doing is the cause of my apparent soft focus. The telescope was focussed ok, I used a Bahtinov mask to check. I feel a new thread coming in the Networking and Wireless section!

Regards

Graeme
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stuck
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Re: Messier 51

Post by stuck »

Graeme wrote:
28 Mar 2022, 16:54
...soft focus...
Don't be so hard on yourself. It's not a failing, it's a feature. It gives the image a pleasant dreamy feeling :thumbup:

Ken

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HansV
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Re: Messier 51

Post by HansV »

It's a lovely photo!
Best wishes,
Hans

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Graeme
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Re: Messier 51

Post by Graeme »

Thanks Ken and thanks Hans.

The softness does work on this target but the whole thing should be sharper. I need to find out if it's an electronics issue or an optics issue!
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ChrisGreaves
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Re: Messier 51

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Graeme wrote:
28 Mar 2022, 16:54
Here's Messier 51, two galaxies crashing into each other.
Hi Graeme.
Are these galaxies truly "crashing into each other", or is that just a trick of position (as in, the stars in a constellation are not close to each other, just grouped into a narrow cone of visibility as seen from our solar system)?
Is the "the small, yellowish galaxy at the outermost tip of one of the arms" colliding, or is it just close enough to have snagged the tip of an arm of Messier as the galaxies reach their closest point of meeting?
And if the two are colliding, are they colliding in the sense we use on the those "idiot drivers YouTube clips", or do they really just pass through each other, what with space being so empty?
I just thought of something else: "colliding" suggests to me that two objects (or regions of space) are approaching each other along intersecting paths (usually taken as straight lines), and I think that that is behind my first three questions. In a "head on" collision the objects approach along the one straight line.
Thanks
Chris
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HansV
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Re: Messier 51

Post by HansV »

The NASA article states
Hubble’s clear view shows that NGC 5195 is passing behind M51. The small galaxy has been gliding past the Whirlpool for hundreds of millions of years.
So it's probably not a real collision. But even when galaxies collide, which happens frequently, they pass through each other, distorting both. They might eventually merge to a single galaxy, but they don't come to a stand-still as when cars collide.
Best wishes,
Hans

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Graeme
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Re: Messier 51

Post by Graeme »

Sorry for the delay, I got distracted. The stars that make up the galaxies pass by each other since the size of a star is almost negligible compared to the distance between stars but they gravitationally interreact to a huge degree. Dark matter makes up a lot more of the mass than baryonic matter and a galactic dark matter halo is thought to extend well beyond the area of space where the stars are, so the stars in the galaxies don't have to crash into each other to pull the galaxies out of shape. As Hans says, this happens frequently, this is how galaxies evolve. The Milky Way has swallowed up loads of dwarf galaxies over the years! The Small and Large Magellanic Clouds are either in the process of being swallowed or they have passed through the Milky way and are now in orbit.

Galaxies mostly hang around in groups all spinning and orbiting each other. There's not a lot of straight line collisions. They eventually merge into one massive elliptical galaxy. This will happen to the Milky Way, the Andromeda Galaxy, the Triangulum Galaxy and a load of dwarf galaxies. Collectively they're referred to as the Local Group. Presumably once they all merge into an elliptical galaxy it will be called Milktridromeda?

Regards

Graeme
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ChrisGreaves
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Re: Messier 51

Post by ChrisGreaves »

Graeme wrote:
31 Mar 2022, 21:17
... once they all merge into an elliptical galaxy it will be called Milktridromeda?
... and will appear as a constellation that looks like a lactating camel?

Thanks Graeme. From my reading I was of the idea that space is called space because it is - empty! Early writings on galaxies, in particular talking about The Universe - dwell on the plum-pudding analogy, with the galaxies (plums) evenly distributed throughout the pudding, hence in the expanding universe, all plums drifting apart.
These days I can see the improbability of an exactly-spaced set of galaxies, so it makes sense (to me) to think of an uneven spacing, and, with astronomical time available, that gravitational interactions must occur, and hence clusters, groups, families or whatever.

Sadly, my brain evolved for the savannah, so i keep forgetting to think about non-baryonic matter.
But I am getting there.
The Milky Way has swallowed up loads of dwarf galaxies over the years!
My savannic brain has decided not to ask how "they" know this, but at first wonders whether such amalgamations causes a galaxy to undergo a violent change in shape, but then I think that a galaxy's shape is really just how we see it from our point of view. That is, that all galaxies are rotating spirals when viewed from well outside the plane, blobs when viewed from a distance, and so on

Cheers
Chris
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Graeme
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Re: Messier 51

Post by Graeme »

ChrisGreaves wrote:
01 Apr 2022, 06:00
The Milky Way has swallowed up loads of dwarf galaxies over the years!
My savannic brain has decided not to ask how "they" know this,

Have a read of this:

https://ras.ac.uk/news-and-press/resear ... deciphered


Galaxy evolution is one of my favourite astronomy subjects! Well, that and cosmology, oh and stellar physics and astrobiology. Oh yeah, and astrophotography!

Thanks for your questions Chris.

Regards

Graeme
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