Starship Asterisk*

Danny wrote: ↑Fri Jun 05, 2020 3:55 pm If you lived on a planet in the ‘tail’ that extends from this galaxy, would the spiral part of the main galaxy fill your night sky?

johnnydeep wrote: ↑Thu Jun 04, 2020 10:23 pm
My pleasure! Yeah, I was slightly worried about the size of that pic, but I figured if it was too big, it would have been flagged as such and not let me use it. But, 1 MB isn't really that big these days, is it? That said, I did take your recommendation and edited my original post as you suggested. [EDIT: But wait a minute now. Aren't all these images just links to off-site data (except that is for any attachment pics that you uploaded from your own PC)?]

Ann wrote: ↑Thu Jun 04, 2020 6:15 pm

johnnydeep wrote: ↑Thu Jun 04, 2020 5:56 pm

Ann wrote: ↑Thu Jun 04, 2020 3:40 pm

Yes, that must be it.

Ann

Ok. I found this pic that better shows - at least to my mind - that blur of stars as a more convincingly distinct object: view the expanded image to see it clearly. I can even imagine that it could be one of NGC 3628's "Magellanic clouds"!

Great picture, Johnny! I absolutely agree with you that the dwarf galaxy resembles the Large Magellanic Cloud. There is a grainy "body" that looks like a bar, similar to the bar of the LMC, and then there is what looks like a huge cyan-colored region of massive OIII-rich star formation - the NGC 3628 satellite galaxy's own Tarantula Nebula!

The picture you have posted is big, 1.04 MB, and I'm not sure you're allowed to post anything that big. I think the limit is 400 KB, although I myself certainly post pictures as big as, say, 450 KB. I don't dare post anything bigger than 500 KB, though, and I try to stay below 450 KB.

You can find smaller sizes of the picture you posted at this site. There are two versions of the image that are smaller than 400 KB. If I were you, I would post one of the two smaller versions, and then suggest that people should click to see the full size image.

Thanks for finding the picture for us!

Ann

johnnydeep wrote: ↑Thu Jun 04, 2020 5:56 pm Ok. I found this pic ...
[ NGC 3628, Spiral Galaxy in Leo
Composite Image from Multiple Data Sources
8.2 Meter Subaru Telescope (NAOJ)
Hubble Space Telescope
Color data Marco Burali
MTM OBSERVATORY ITALY (www.osservatoriomtm.it)"]
http://www.robgendlerastropics.com/NGC3 ... HST-LL.jpg ]

johnnydeep wrote: ↑Thu Jun 04, 2020 5:56 pm

Ann wrote: ↑Thu Jun 04, 2020 3:40 pm

johnnydeep wrote: ↑Thu Jun 04, 2020 2:56 pm

So, is this the nearby small galaxy being referred to?

NGC3628.jpg

Yes, that must be it.

Ann

Ok. I found this pic that better shows - at least to my mind - that blur of stars as a more convincingly distinct object: view the expanded image to see it clearly. I can even imagine that it could be one of NGC 3628's "Magellanic clouds"!

NGC 3628, Spiral Galaxy in Leo Composite Image from Multiple Data Sources 8.2 Meter Subaru Telescope (NAOJ) Hubble Space Telescope Color data Marco Burali MTM OBSERVATORY ITALY (www.osservatoriomtm.it)

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Ann wrote: ↑Thu Jun 04, 2020 3:40 pm

johnnydeep wrote: ↑Thu Jun 04, 2020 2:56 pm

APOD Robot wrote: ↑Thu Jun 04, 2020 4:05 am It also reveals a small galaxy nearby, likely a satellite of NGC 3628

So, is this the nearby small galaxy being referred to?

NGC3628.jpg

Yes, that must be it.

Ann

johnnydeep wrote: ↑Thu Jun 04, 2020 2:56 pm

APOD Robot wrote: ↑Thu Jun 04, 2020 4:05 am It also reveals a small galaxy nearby, likely a satellite of NGC 3628

So, is this the nearby small galaxy being referred to?

NGC3628.jpg

Chris Peterson wrote: ↑Thu Jun 04, 2020 3:12 pm

johnnydeep wrote: ↑Thu Jun 04, 2020 3:03 pm

Chris Peterson wrote: ↑Thu Jun 04, 2020 2:52 pm

These kinds of gradients are distributed over thousands or even millions of light years. They simply aren't significant over one light year.

Ok, but then how close are nearby stars getting to our sun to nudge Oort cloud objects as I've often seen posited as the cause of some mass extinctions on Earth? Or are you saying that the galactic tidal forces are swamped in magnitude by what I'll call "gravitational brownian motion" of nearby stars?

When stars pass within a few light years of the Solar System they might perturb the Oort cloud. A star that is a few light years away exerts many orders of magnitude greater tidal forces on the Solar System than a pair of interacting galaxies does on the scale of a stellar system. The gravitational gradient from the latter is so small that two stars separated by even hundreds of light years will not experience significantly different forces. So within local regions, not stars are going to be perturbed relative to other local stars. They all see essentially identical forces.

johnnydeep wrote: ↑Thu Jun 04, 2020 3:03 pm

Chris Peterson wrote: ↑Thu Jun 04, 2020 2:52 pm

johnnydeep wrote: ↑Thu Jun 04, 2020 2:50 pm

Well, couldn't there be an increased chance of nearby star perturbations nudging Oort cloud objects inward and thereby increasing the likelihood of planetary impacts? Or are these tidal tails already less dense in stars than in the galaxy proper, and thereby safer places for life to begin with?

These kinds of gradients are distributed over thousands or even millions of light years. They simply aren't significant over one light year.

Ok, but then how close are nearby stars getting to our sun to nudge Oort cloud objects as I've often seen posited as the cause of some mass extinctions on Earth? Or are you saying that the galactic tidal forces are swamped in magnitude by what I'll call "gravitational brownian motion" of nearby stars?

Chris Peterson wrote: ↑Thu Jun 04, 2020 2:52 pm

johnnydeep wrote: ↑Thu Jun 04, 2020 2:50 pm

Chris Peterson wrote: ↑Thu Jun 04, 2020 2:23 pm

The tidal forces are infinitesimally small on the scale of something the size of a planetary system. There would be no detectable impact.

Well, couldn't there be an increased chance of nearby star perturbations nudging Oort cloud objects inward and thereby increasing the likelihood of planetary impacts? Or are these tidal tails already less dense in stars than in the galaxy proper, and thereby safer places for life to begin with?

These kinds of gradients are distributed over thousands or even millions of light years. They simply aren't significant over one light year.

APOD Robot wrote: ↑Thu Jun 04, 2020 4:05 am It also reveals a small galaxy nearby, likely a satellite of NGC 3628

johnnydeep wrote: ↑Thu Jun 04, 2020 2:50 pm

Chris Peterson wrote: ↑Thu Jun 04, 2020 2:23 pm

sillyworm 2 wrote: ↑Thu Jun 04, 2020 1:45 pm Let's say you had a solar system in one of these tidal fields...would life on a planet go on as normal? I know this would be an incredibly slow process.

The tidal forces are infinitesimally small on the scale of something the size of a planetary system. There would be no detectable impact.

Well, couldn't there be an increased chance of nearby star perturbations nudging Oort cloud objects inward and thereby increasing the likelihood of planetary impacts? Or are these tidal tails already less dense in stars than in the galaxy proper, and thereby safer places for life to begin with?

Chris Peterson wrote: ↑Thu Jun 04, 2020 2:23 pm

sillyworm 2 wrote: ↑Thu Jun 04, 2020 1:45 pm Let's say you had a solar system in one of these tidal fields...would life on a planet go on as normal? I know this would be an incredibly slow process.

The tidal forces are infinitesimally small on the scale of something the size of a planetary system. There would be no detectable impact.

sillyworm 2 wrote: ↑Thu Jun 04, 2020 1:45 pm Let's say you had a solar system in one of these tidal fields...would life on a planet go on as normal? I know this would be an incredibly slow process.