APOD: NGC 247 and Friends (2018 Mar 30)

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APOD: NGC 247 and Friends (2018 Mar 30)

Post by APOD Robot » Fri Mar 30, 2018 4:06 am

Image NGC 247 and Friends

Explanation: About 70,000 light-years across, NGC 247 is a spiral galaxy smaller than our Milky Way. Measured to be only 11 million light-years distant it is nearby though. Tilted nearly edge-on as seen from our perspective, it dominates this telescopic field of view toward the southern constellation Cetus. The pronounced void on one side of the galaxy's disk recalls for some its popular name, the Needle's Eye galaxy. Many background galaxies are visible in this sharp galaxy portrait, including the remarkable string of four galaxies just below and left of NGC 247 known as Burbidge's Chain. Burbidge's Chain galaxies are about 300 million light-years distant. The deep image even reveals that the two leftmost galaxies in the chain are apparently interacting, joined by a faint bridge of material. NGC 247 itself is part of the Sculptor Group of galaxies along with the shiny spiral NGC 253.

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by Ann » Fri Mar 30, 2018 4:54 am

APOD Robot wrote:

The pronounced void on one side of the galaxy's disk recalls for some its popular name, the Needle's Eye galaxy.
Perhaps a camel could pass through it? :wink:

Asymmetrical NGC 5474. Adam Block/NOAO/AURA/NSF
Wonder how NGC 247 got that way? Well, many if most galaxies are a bit asymmetrical. Some are more asymmetrical than most.

To return to the APOD, Burbidge's Chain looks fantastic. The most interesting thing about it is that all four galaxies look blue, with a healthy amount of star formation.

That can only mean, in my opinion, that the galaxies can't have been interacting for a very long time, or the steep and variable gravity wells would have depleted them of gas.

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by Boomer12k » Fri Mar 30, 2018 8:39 am

247 looks like it is in motion, (and it is, however),...I mean by APPEARANCE... there is a place on the right side that is striated, and looks "streaked"... making it look like "motion blur".

I wonder if the "voids" are from a MERGER. And the striation on the right is from that. a smaller galaxy gets caught, does not escape, and is falling back into the capturing galaxy... my thought as to what is causing the voids... it went by, got splayed out, and streams back in... looping... causing the voids... well...my GUESS...

Either something like that, or maybe there is a galaxy nearby we don't see in-shot, that is interacting with it.

VERY NICE IMAGE!!!!

I have been lucky with a couple of clear nights with the nearing and nearly Full Moon, and got out the scopes and had some nice viewing...can't wait for warmer weather.

:---[===] *

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by neufer » Fri Mar 30, 2018 11:26 am

Boomer12k wrote:
Fri Mar 30, 2018 8:39 am

247 looks like it is in motion, (and it is, however),...I mean by APPEARANCE...there is a place
on the right side that is striated, and looks "streaked"... making it look like "motion blur".
  • Please try to use the proper scientific terminology:
https://www.fastcodesign.com/1673017/quimps-plewds-and-grawlixes-the-secret-language-of-comic-strips wrote:

Quimps, Plewds, And Grawlixes: The Secret Language Of Comic Strips

<<In 1980, Mort Walker–the creator of comic strips like Beetle Bailey and Hi and Lois–published a charming book titled The Lexicon of Comicana. Barely 96 pages, mostly cartoons and white space, The Lexicon was Walker’s attempt to classify the symbols used in comic strips around the world. You’ve probably never heard of a blurgit or a swalloop or a grawlix or an agitron, but you see them every day in your newspaper’s comics section. Here’s a primer on the secret language of comic symbols.

In a section of the book devoted to lines cartoonists use to show motion, Walker coins some more great terminologies. For example, any line used to show something moving is called a sphericasia. Shake something hard enough and these lines are called agitrons, while the lines that show which way a comic strip character is pointing are called digitrons. And when Sarge punches Beetle Bailey in the comics, the punch is made up of three distinct elements: A little dust cloud called a briffit to show where the punch started, a swalloop to show the arc of the fist as it smashes across Beetle’s jaw, and the terminating point at the end, which is a whitope. Speaking of briffits, they are most often found in the comic strips in the accompaniment of hites: horizontal lines streaking between a cartoon character and his briffit to represent speed. “The more hites, the more speed,” Walker explains. But there are also vites and dites. As their names imply, these are vertical and diagonal hites, but they don’t show speed. Instead, they show that an object is reflective. There are also uphites and downhites, which come out of a character when he is jumping or falling.>>
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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by NCTom » Fri Mar 30, 2018 12:33 pm

How reasonable is it to believe most of the points of light in this photo are galaxies other than the obvious stars in our own galaxy with their photo spikes? Also the enlarged photo shows numerous bright red dots which in a galaxy I would think were emission nebulae but here are widely dispersed between galaxies. How does such a bright red come into play? I have forgotten way too much from my astronomy lessons.

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by bls0326 » Fri Mar 30, 2018 1:10 pm

The distances, depth, and details of these astronomy pictures continue to amaze me. Great!

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by neufer » Fri Mar 30, 2018 1:59 pm

NCTom wrote:
Fri Mar 30, 2018 12:33 pm

the enlarged photo shows numerous bright red dots which in a galaxy I would think were emission nebulae but here are widely dispersed between galaxies. How does such a bright red come into play? I have forgotten way too much from my astronomy lessons.
https://en.wikipedia.org/wiki/H_II_region wrote:
https://apod.nasa.gov/apod/ap171116.html

<<An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically a cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about a million particles per cubic cm. The Orion Nebula, now known to be an H II region, was observed in 1610 by Nicolas-Claude Fabri de Peiresc by telescope, the first such object discovered. Chemically, H II regions consist of about 90% hydrogen. The strongest hydrogen emission line at 656.3 nm gives H II regions their characteristic red colour. Most of the rest of an H II region consists of helium, with trace amounts of heavier elements. Across the galaxy, it is found that the amount of heavy elements in H II regions decreases with increasing distance from the galactic centre. This is because over the lifetime of the galaxy, star formation rates have been greater in the denser central regions, resulting in greater enrichment of those regions of the interstellar medium with the products of nucleosynthesis.

The term H II is pronounced "H two" by astronomers [as opposed to say: "two Corinthians" said by some Presidents]. It is customary in astronomy to use the Roman numeral I for neutral atoms, II for singly-ionised—H II is H+ in other sciences—III for doubly-ionised, e.g. O III is O++, etc. H II, or H+, consists of free protons. An H I region being neutral atomic hydrogen, and a molecular cloud being molecular hydrogen, H2.

H II regions may be of any shape, because the distribution of the stars and gas inside them is irregular. The short-lived blue stars created in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas. H II regions—sometimes several hundred light-years across—are often associated with giant molecular clouds. They often appear clumpy and filamentary, sometimes showing bizarre shapes such as the Horsehead Nebula. H II regions may give birth to thousands of stars over a period of several million years. In the end, supernova explosions and strong stellar winds from the most massive stars in the resulting star cluster will disperse the gases of the H II region, leaving behind a cluster of stars which have formed, such as the Pleiades.

H II regions can be observed at considerable distances in the universe, and the study of extragalactic H II regions is important in determining the distance and chemical composition of galaxies. Spiral and irregular galaxies contain many H II regions, while elliptical galaxies are almost devoid of them. In spiral galaxies, including our Milky Way, H II regions are concentrated in the spiral arms, while in irregular galaxies they are distributed chaotically. Some galaxies contain huge H II regions, which may contain tens of thousands of stars. Examples include the 30 Doradus region in the Large Magellanic Cloud and NGC 604 in the Triangulum Galaxy.

A few of the brightest H II regions are visible to the naked eye. However, none seem to have been noticed before the advent of the telescope in the early 17th century. Even Galileo did not notice the Orion Nebula when he first observed the star cluster within it (previously cataloged as a single star, θ Orionis, by Johann Bayer). The French observer Nicolas-Claude Fabri de Peiresc is credited with the discovery of the Orion Nebula in 1610. Since that early observation large numbers of H II regions have been discovered in the Milky Way and other galaxies.

William Herschel observed the Orion Nebula in 1774, and described it later as "an unformed fiery mist, the chaotic material of future suns". In early days astronomers distinguished between "diffuse nebulae" (now known to be H II regions), which retained their fuzzy appearance under magnification through a large telescope, and nebulae that could be resolved into stars, now know to be galaxies external to our own.

The precursor to an H II region is a giant molecular cloud (GMC). A GMC is a cold (10–20 K) and dense cloud consisting mostly of molecular hydrogen. GMCs can exist in a stable state for long periods of time, but shock waves due to supernovae, collisions between clouds, and magnetic interactions can trigger its collapse. When this happens, via a process of collapse and fragmentation of the cloud, stars are born (see stellar evolution for a lengthier description).

As stars are born within a GMC, the most massive will reach temperatures hot enough to ionise the surrounding gas. Soon after the formation of an ionising radiation field, energetic photons create an ionisation front, which sweeps through the surrounding gas at supersonic speeds. At greater and greater distances from the ionising star, the ionisation front slows, while the pressure of the newly ionised gas causes the ionised volume to expand. Eventually, the ionisation front slows to subsonic speeds, and is overtaken by the shock front caused by the expansion of the material ejected from the nebula. The H II region has been born.

The lifetime of an H II region is of the order of a few million years. Radiation pressure from the hot young stars will eventually drive most of the gas away. In fact, the whole process tends to be very inefficient, with less than 10 percent of the gas in the H II region forming into stars before the rest is blown off. Contributing to the loss of gas are the supernova explosions of the most massive stars, which will occur after only 1–2 million years. The full details of massive star formation within H II regions are not yet well known. Two major problems hamper research in this area. First, the distance from Earth to large H II regions is considerable, with the nearest H II (California Nebula) region at 300 pc (1,000 light-years); other H II regions are several times that distance from Earth. Secondly, the formation of these stars is deeply obscured by dust, and visible light observations are impossible. Radio and infrared light can penetrate the dust, but the youngest stars may not emit much light at these wavelengths.>>
Art Neuendorffer

NCTom

Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by NCTom » Fri Mar 30, 2018 2:52 pm

Thanks so much, neufer. I hope others will benefit as much as I have from your response.

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by orin stepanek » Fri Mar 30, 2018 3:34 pm

With a little resizing; NGC247 makes a nice wallpaper! :D
Orin

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by Sa Ji Tario » Fri Mar 30, 2018 3:45 pm

Of the two galaxies that act on the right it seems to tear to the benefit of the left

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by neufer » Fri Mar 30, 2018 4:54 pm

Sa Ji Tario wrote:
Fri Mar 30, 2018 3:45 pm

Of the two galaxies that act on the right it seems to tear to the benefit of the left
http://www.roh.org.uk/news/exit-pursued-by-a-bear-how-do-you-approach-shakespeares-famous-stage-direction wrote:
'Exit, pursued by a bear':
How do you approach Shakespeare's famous stage direction?

By Elizabeth Davis (Former Editorial Assistant) 10 April 2014 at 5.40pm

<<It’s not often that a play is best known for one stage direction. But then not many stage directions are as memorable as the one that appears in Act III of Shakespeare’s The Winter’s Tale: ‘Exit, pursued by a bear.’

The character being pursued is Antigonus, a lord of Sicilia, who has been ordered to abandon the baby Princess Perdita . He is interrupted in his cruel errand by the arrival of the bear, an encounter that proves fatal for him – but not for the baby.

Frustratingly, 17th-century accounts of early stagings of the play make no mention of the bear’s appearance. It’s not impossible that a real bear was used at the premiere. The Globe Theatre was, after all, not far from the city’s bear-baiting pits. But, as Shakespeare scholars Susan Snyder and Deborah T. Curren-Aquino have pointed out, these bears were far from tame: ‘even less likely is a bear trained to the point where it could be trusted to wait backstage, enter on cue, and rush at Antigonus without mauling him.’

Another theory has gained credence in the last few years. In 1609 (around the time the play was written) King James I was given two polar bear cubs that had been captured on a voyage to the Arctic. One of these cubs could well have featured in the premiere – a bear cub would have been much less dangerous than a full-grown animal, and would surely have been a hit with audiences.

For a multitude of very sensible reasons, real bears are now unlikely to be used in productions of The Winter’s Tale. Representations of the bear have generally fallen into two types: realistic (an actor in a bear suit) and more conceptual.

On the realistic side, Charles Kean’s bear in his 1856 production was praised in The Times as ‘a masterpiece of the zoological art’. An early 20th-century production by Harley Granville-Barker and a 1951 staging by Peter Brook were both praised for having convincingly ferocious bears.

But the problem with the bear-suit approach is that the scene can often end up being funny – and this direction is about a man being mauled to death. That essential mismatch has led directors to search for less ‘pantomime’ ways of staging the scene.

Conceptual versions of the stage direction have included a shadow of a bear seen in a flash of lightning (director Ronald Eyre, 1981), a bear evoked by a screech and a growl (James Lapine, 1989) and, in Greg Doran’s 1999 production for the Royal Shakespeare Company, the fallen canopy of the Sicilian palace morphed into the shape of a bear. In a 1986 production by Terry Hands a polar bear rug reared up to chase off the terrified Antigonus.

Choreographer Christopher Wheeldon is keeping tight-lipped about how he’ll be staging the scene for The Royal Ballet – but he has said the famous bear moment won’t involve any dancers…>>
Art Neuendorffer

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by Chris Peterson » Fri Mar 30, 2018 5:22 pm

NCTom wrote:
Fri Mar 30, 2018 12:33 pm
How reasonable is it to believe most of the points of light in this photo are galaxies other than the obvious stars in our own galaxy with their photo spikes?
A good deal of information is lost in converting an image like this to a color JPEG. However, if you were to take the original data and run it through a source extraction tool like SExtractor, most of those near-point-like objects would be readily distinguishable from stars. Stars are true point sources, and that means their intensity profile in the image is the same for all- a Gaussian-like shape that is the product of nothing but the optics. Galaxies are extended sources, and even ones so distant that they appear visually to be a point usually show a different intensity profile that distinguishes them from stars.

There's also a statistical argument to be made, that we don't expect to find many stars in a field of this size, but we do expect to find a lot of distant galaxies.
Chris

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by Ironwood » Fri Mar 30, 2018 5:22 pm

Speaking of perspective, I find it strange that my mind always assigns the perspective of the top half of a tilted spiral galaxy as being farther away from me than the bottom half. We obviously aren't viewing them all from "above".

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by MarkBour » Fri Mar 30, 2018 5:53 pm

Boomer12k wrote:
Fri Mar 30, 2018 8:39 am
247 looks like it is in motion, (and it is, however),...I mean by APPEARANCE... there is a place on the right side that is striated, and looks "streaked"... making it look like "motion blur".

I wonder if the "voids" are from a MERGER. And the striation on the right is from that. a smaller galaxy gets caught, does not escape, and is falling back into the capturing galaxy... my thought as to what is causing the voids... it went by, got splayed out, and streams back in... looping... causing the voids... well...my GUESS...

Either something like that, or maybe there is a galaxy nearby we don't see in-shot, that is interacting with it.

VERY NICE IMAGE!!!!

I have been lucky with a couple of clear nights with the nearing and nearly Full Moon, and got out the scopes and had some nice viewing...can't wait for warmer weather.

:---[===] *
In addition to the voids and streaks (err... excuse me, "hites"), it seems to me that the central region is a train wreck. I think your main theory is that of a capture of a smaller galaxy, and that it is almost finished. That would be my guess as well. (Unfortunately for your theory, my having the same idea does not lend much support -- I have a woeful track record for astronomical conjecture.)
Ironwood wrote:
Fri Mar 30, 2018 5:22 pm
Speaking of perspective, I find it strange that my mind always assigns the perspective of the top half of a tilted spiral galaxy as being farther away from me than the bottom half. We obviously aren't viewing them all from "above".
Fascinating point! It was not until you pointed that out that I realized I have the same psychological bias. Now, I'm imagining how much motion it would take to cause an image of such a galaxy to swing around so that parallax would tell us which was the closer part. (Immense!) But Doppler measurements should be able to tell us which is which for any galaxy, right? (Or, from Art's post, perhaps we can just look for the swalloops from the stars.)

With a number like 247, I think we could also call this the "We're Always Open Galaxy".
Mark Goldfain

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by Chris Peterson » Fri Mar 30, 2018 5:59 pm

Ironwood wrote:
Fri Mar 30, 2018 5:22 pm
Speaking of perspective, I find it strange that my mind always assigns the perspective of the top half of a tilted spiral galaxy as being farther away from me than the bottom half. We obviously aren't viewing them all from "above".
No... but we view almost everything in our world from above, so the fact that our visual processing engine works this way makes perfect sense.
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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by MarkBour » Fri Mar 30, 2018 6:07 pm

Capture1.JPG
An alternate theory, of course, is that we have just located the Rebel Alliance's galaxy, and they are trying to sneak away from us ...
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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by Ann » Fri Mar 30, 2018 6:45 pm

Ironwood wrote:
Fri Mar 30, 2018 5:22 pm
Speaking of perspective, I find it strange that my mind always assigns the perspective of the top half of a tilted spiral galaxy as being farther away from me than the bottom half. We obviously aren't viewing them all from "above".
The Andromeda Galaxy. Photo: Terry Hancock.
NGC 247 and friends.
CHART32 Team, Processing - Johannes Schedler




















In some cases, it is indeed possible to say which side of a galaxy is closer to us. The Andromeda galaxy is such a galaxy. Note that the dust lanes on one side of the main disk look very dark, but the dust lanes on the other side of the disk look much fainter.

The reason for this is that the dust lanes that are closest to us will directly block light that comes from behind them, if the galaxy has sufficiently obvious dust lanes and is seen at just the right angle. The dust lanes on the other side of the disk will often reflect light our way, making them look a lot less dark.

Unfortunately we can't use that method to determine which side of the disk of NGC 247 is closest to us, because NGC 247 has rather thin, broken and spotty dust lanes. I think perhaps the dust lanes at top look a little darker than the ones at bottom, but who's to say?

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by MarkBour » Fri Mar 30, 2018 7:27 pm

MarkBour wrote:
Fri Mar 30, 2018 5:53 pm
Ironwood wrote:
Fri Mar 30, 2018 5:22 pm
Speaking of perspective, I find it strange that my mind always assigns the perspective of the top half of a tilted spiral galaxy as being farther away from me than the bottom half. We obviously aren't viewing them all from "above".
Fascinating point! It was not until you pointed that out that I realized I have the same psychological bias. Now, I'm imagining how much motion it would take to cause an image of such a galaxy to swing around so that parallax would tell us which was the closer part. (Immense!) But Doppler measurements should be able to tell us which is which for any galaxy, right? (Or, from Art's post, perhaps we can just look for the swalloops from the stars.)
I have to retract my statement that Doppler measurements should be able to sort this out. As I understand it, the only thing we can measure from Doppler shifts is just the vector component exactly along our line-of-sight. At first I thought you could map these for various parts of the galaxy to determine direction of rotation. And I think that is correct, but that does not in any way tell you which half of an image like this is the closer half. You'd still need some other piece of information.

I see that Ann's post above describes a better approach to the issue.

Also, I see Phil Platt did a nice article here:
http://www.slate.com/blogs/bad_astronom ... tions.html
Just knowing the overall rotation does not seem to be enough, nor does knowing the Doppler shifts. But both together, I think that would be sufficient information.
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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by neufer » Fri Mar 30, 2018 8:51 pm

MarkBour wrote:
Fri Mar 30, 2018 7:27 pm
MarkBour wrote:
Fri Mar 30, 2018 5:53 pm
Ironwood wrote:
Fri Mar 30, 2018 5:22 pm

Speaking of perspective, I find it strange that my mind always assigns the perspective of the top half of a tilted spiral galaxy as being farther away from me than the bottom half. We obviously aren't viewing them all from "above".
Fascinating point! It was not until you pointed that out that I realized I have the same psychological bias. Now, I'm imagining how much motion it would take to cause an image of such a galaxy to swing around so that parallax would tell us which was the closer part. (Immense!) But Doppler measurements should be able to tell us which is which for any galaxy, right? (Or, from Art's post, perhaps we can just look for the swalloops from the stars.)
I have to retract my statement that Doppler measurements should be able to sort this out. As I understand it, the only thing we can measure from Doppler shifts is just the vector component exactly along our line-of-sight. At first I thought you could map these for various parts of the galaxy to determine direction of rotation. And I think that is correct, but that does not in any way tell you which half of an image like this is the closer half. You'd still need some other piece of information.
Almost all spiral galaxies rotate (intuitively) in opposite direction from the lagging spiral arms.
(A constant rotational velocity = an angular rotation rate that drops as 1/R.)

This in combination with Doppler measurements should be sufficient to determine which half is the closer half.

(A telescope capable of observing swalloops should confirm this.)
MarkBour wrote:
Fri Mar 30, 2018 7:27 pm

I see that Ann's post above describes a better approach to the issue.

Also, I see Phil Platt did a nice article here:
http://www.slate.com/blogs/bad_astronom ... tions.html
Just knowing the overall rotation does not seem to be enough, nor does knowing the Doppler shifts. But both together, I think that would be sufficient information.
  • NGC 247 is 2,000 times further away than the Large Magellanic Cloud.
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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by MarkBour » Fri Mar 30, 2018 10:28 pm

neufer wrote:
Fri Mar 30, 2018 8:51 pm
Also, I see Phil Platt did a nice article here:
http://www.slate.com/blogs/bad_astronom ... tions.html
Just knowing the overall rotation does not seem to be enough, nor does knowing the Doppler shifts. But both together, I think that would be sufficient information.
  • NGC 247 is 2,000 times further away than the Large Magellanic Cloud.
[/quote]
From Phil Platt's article, I figured it might just be a matter of time before someone can do this with some more galaxies, though they are all far more distant. I don't know how much sensitivity and how much time would be needed to scale this up, though. Based on what you just said, I guess 2000 times the sensitivity would be required for NGC 247? One could probably trade off time for sensitivity. I don't know if the technique required being able to resolve individual stars in the LMC. I would not at first suppose that that was a requirement.
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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by sillyworm2 » Fri Mar 30, 2018 10:57 pm

https://www.eso.org/public/images/eso1107a/ And there is THIS perspective....as well as the optional galaxy link point of view in the info to the right.

kindness

Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by kindness » Sat Mar 31, 2018 1:04 am

I wonder how far apart the galaxies of Burbidge's Chain are from each other. I've found the distance to them, the relative direction they are traveling but no not of what the distances between them are. Anyone know?

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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by neufer » Sat Mar 31, 2018 1:35 am

kindness wrote:
Sat Mar 31, 2018 1:04 am

I wonder how far apart the galaxies of Burbidge's Chain are from each other. I've found the distance to them, the relative direction they are traveling but no not of what the distances between them are. Anyone know?
They are about an arc-minute apart which is ~20 kpc at at distance of ~62 Mpc.
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Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by Ann » Sat Mar 31, 2018 6:03 am

neufer wrote:
Sat Mar 31, 2018 1:35 am
kindness wrote:
Sat Mar 31, 2018 1:04 am

I wonder how far apart the galaxies of Burbidge's Chain are from each other. I've found the distance to them, the relative direction they are traveling but no not of what the distances between them are. Anyone know?
They are about an arc-minute apart which is ~20 kpc at at distance of ~62 Mpc.
And how much is 20 kpc?

Okay. Since I'm so dumb at math, I always skip all decimals and calculate in the simplest way. A parsec is (I looked it up) 3.26163344 light-years. Well, fascinating. I'll say that it's 3 light-years.

"Kilo" means a thousand, so a kiloparsec is a thousand parsecs, or a thousand times three light-years. So, 3,000 light-years. Now were getting somewhere.

And even I should be able to multiply 3,000 light-years by 20. It's 60,000, so the Burbidge's Chain galaxies are about 60,000 light-years apart. Actually, the distance between them will be a bit greater, since a parsec is a bit more than 3 light-years. Maybe the average distance between the Burbidge galaxies is 70,000 light-years. Same difference.

To put that distance in perspective, we may remember that the distance between the Milky Way and the Large Magellanic Cloud is ~160,000 light-years. And the Andromeda galaxy is about 2.5 million light-years away.

So the Burbidge's Chain galaxies live in close and neighborly proximity.

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starsurfer
Stellar Cartographer
Posts: 3140
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: NGC 247 and Friends (2018 Mar 30)

Post by starsurfer » Sat Mar 31, 2018 1:20 pm

Awesome image, it's so rare to see this field of view!

Some might find this paper interesting.