APOD: NGC 4565: Galaxy on Edge (2021 May 17)

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APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by APOD Robot » Mon May 17, 2021 4:05 am

Image NGC 4565: Galaxy on Edge

Explanation: Is our Milky Way Galaxy this thin? Magnificent spiral galaxy NGC 4565 is viewed edge-on from planet Earth. Also known as the Needle Galaxy for its narrow profile, bright NGC 4565 is a stop on many telescopic tours of the northern sky, in the faint but well-groomed constellation Coma Berenices. This sharp, colorful image reveals the spiral galaxy's boxy, bulging central core cut by obscuring dust lanes that lace NGC 4565's thin galactic plane. An assortment of other background galaxies is included in the pretty field of view. Thought similar in shape to our own Milky Way Galaxy, NGC 4565 lies about 40 million light-years distant and spans some 100,000 light-years. Easily spotted with small telescopes, sky enthusiasts consider NGC 4565 to be a prominent celestial masterpiece Messier missed.

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by VictorBorun » Mon May 17, 2021 4:37 am

I wonder why every encyclopedia is shy to tell the angle of this galaxy disk to our line of view.

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by Chris Peterson » Mon May 17, 2021 5:05 am

VictorBorun wrote:
Mon May 17, 2021 4:37 am
I wonder why every encyclopedia is shy to tell the angle of this galaxy disk to our line of view.
Isn't it rather obvious?
Chris

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by shaileshs » Mon May 17, 2021 5:38 am

VictorBorun wrote:
Mon May 17, 2021 4:37 am
I wonder why every encyclopedia is shy to tell the angle of this galaxy disk to our line of view.
I found these 2 pages which say it's approx. 87-88 deg tilted -

1) http://www.nightskyinfo.com/archive/ngc4565/
"NGC 4565 is inclined to an angle of 87°, 3° from edge-on."

2) https://academic.oup.com/mnras/article/ ... 797/971155
"For the inclination, we find a best-fitting value of ∼87°.25, which is in agreement with earlier reported results. Indeed, H I observations of the gaseous disc in the past have constrained the inclination >84° (Ruben 1991), with more recent H I observations reporting an inclination angle of 87°.5 (Zschaechner et al. 2012). From a similar radiative transfer study, Alton et al. (2004) estimated an inclination of 88°."

Hope that helps..

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by VictorBorun » Mon May 17, 2021 7:06 am

shaileshs wrote:
Mon May 17, 2021 5:38 am
VictorBorun wrote:
Mon May 17, 2021 4:37 am
I wonder why every encyclopedia is shy to tell the angle of this galaxy disk to our line of view.
I found these 2 pages which say it's approx. 87-88 deg tilted -

1) http://www.nightskyinfo.com/archive/ngc4565/
"NGC 4565 is inclined to an angle of 87°, 3° from edge-on."

2) https://academic.oup.com/mnras/article/ ... 797/971155
"For the inclination, we find a best-fitting value of ∼87°.25, which is in agreement with earlier reported results. Indeed, H I observations of the gaseous disc in the past have constrained the inclination >84° (Ruben 1991), with more recent H I observations reporting an inclination angle of 87°.5 (Zschaechner et al. 2012). From a similar radiative transfer study, Alton et al. (2004) estimated an inclination of 88°."

Hope that helps..
If the Needle Galaxy is a disk seen at 87.25°, then face on it is this disk (Earth-based observer's line is upward, so the dust ring is better seen at the top of the picture, backlighted by the core)

A pair of blue arms must be real and bright jets from the core are just artifacts of stretching the globe core image
[/img2]

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by Ann » Mon May 17, 2021 9:28 am

NGC 4565 in Guide.png

This is what NGC 4656 looks like in my trusted software Guide.

I trust Guide to show me the correct inclination of galaxies.

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by VictorBorun » Mon May 17, 2021 10:30 am

Ann wrote:
Mon May 17, 2021 9:28 am
NGC 4565 in Guide.png
This is what NGC 4656 looks like in my trusted software Guide.
Ann
Seems like the Needle Galaxy proved too much of a needle for this software.
I mean, the visible ellipse of the disk is more narrow than the visible globe of the core.
This case is out of the ordinary.

a disk seen at 87.25° is in lime color:

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by orin stepanek » Mon May 17, 2021 12:04 pm

NGC4565_CFHT_960.jpg

NGC 4565; The Needle Galaxy really has nice clean linrs!


..
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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by Ann » Mon May 17, 2021 12:44 pm

NGC 891 MassimoTuninetti.png
NGC 891. Photo: Massimo Tuninetti.

What, the Color Commentator is posting a picture of NGC 4565 in black and white? Yes, because I wanted to emphasize how extremely long and thin the disk of this galaxy really is. Compare it with the similarly edge-on galaxy NGC 891, whose disk looks (and is, I'm sure) much smaller. Admittedly, the pictures aren't directly comparable, because they have been taken with different cameras, filters and exposure times, and they have been processed differently. Even so, the disk of NGC 4565 really is very flat and extensive!


NGC 4565 seems extremely "calm and undisturbed" to me. Nothing much is bothering this galaxy, which is why its disk has been able to grow so vast. And nothing much is happening "from within", either. There is not a lot of star formation going on in this "island universe". Compare the appearance of NGC 4565 with that of starburst galaxy NGC 4631. The difference is certainly striking!


There is the slightest hint of a warp in the huge disk of NGC 4565. That reminds me of a few other galaxies with warped disks:


So here we have both the Needle galaxy (NGC 4565) and the Twisted Sister (ESO 510-G13). So let's listen to "A needle pulling thread" from Sound of Music, and.... Well, I couldn't find anything I liked by Twisted Sister. Sorry!

Click to play embedded YouTube video.
Sew, a needle pulling thread.
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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by Chris Peterson » Mon May 17, 2021 1:19 pm

VictorBorun wrote:
Mon May 17, 2021 7:06 am
If the Needle Galaxy is a disk seen at 87.25°, then face on it is this disk (Earth-based observer's line is upward, so the dust ring is better seen at the top of the picture, backlighted by the core)

A pair of blue arms must be real and bright jets from the core are just artifacts of stretching the globe core image
You can't optically correct an edge-on galaxy into a face-on view. The galaxy isn't a disk, but a cylinder. Take a picture of a coin from edge-on and try to optically rotate it!

This is very clearly a fairly typical spiral galaxy, without jets. Viewed face on it would appear circular with spiral arms and a bright center.
Chris

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by VictorBorun » Mon May 17, 2021 2:07 pm

Chris Peterson wrote:
Mon May 17, 2021 1:19 pm
The galaxy isn't a disk, but a cylinder. Take a picture of a coin from edge-on and try to optically rotate it!
Yes, the edge of a coin gets thicker at the observer's side. original (alas with some perpective effect) compressed perpendicular to the line of view

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by Chris Peterson » Mon May 17, 2021 2:18 pm

VictorBorun wrote:
Mon May 17, 2021 2:07 pm
Chris Peterson wrote:
Mon May 17, 2021 1:19 pm
The galaxy isn't a disk, but a cylinder. Take a picture of a coin from edge-on and try to optically rotate it!
Yes, the edge of a coin gets thicker at the observer's side. original (alas with some perpective effect) compressed perpendicular to the line of view
Try it again, but from just a degree or two off the edge. Your examples are far from "edge-on".
Chris

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by bystander » Mon May 17, 2021 2:40 pm

Ann wrote:
Mon May 17, 2021 12:44 pm
...
Well, I couldn't find anything I liked by Twisted Sister. Sorry!
Twisted Sister - We're Not Gonna Take It
Click to play embedded YouTube video.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by VictorBorun » Mon May 17, 2021 3:59 pm

Chris Peterson wrote:
Mon May 17, 2021 2:18 pm
Try it again, but from just a degree or two off the edge.

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by Chris Peterson » Mon May 17, 2021 4:23 pm

VictorBorun wrote:
Mon May 17, 2021 3:59 pm
Chris Peterson wrote:
Mon May 17, 2021 2:18 pm
Try it again, but from just a degree or two off the edge.
The coins on the right are basically what we see with this galaxy. (All the more confused by the fact that the galaxy isn't perfectly flat, so we have obscuring material along the edge.
Chris

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by saturno2 » Mon May 17, 2021 9:47 pm

image very interesting

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by Ann » Tue May 18, 2021 4:52 am


I read somewhere that NGC 4565 would look like M100 if we could see it face on.

Well, that's possible. Or not. Because no two spiral galaxies look the same. And personally, I'm convinced that the disk of NGC 4565 is (much) larger than the disk of M100.

But both these galaxies are large and "calm", so I guess they have something in common.

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Re: APOD: NGC 4565: Galaxy on Edge (2021 May 17)

Post by VictorBorun » Tue May 18, 2021 9:05 am

Ann wrote:
Tue May 18, 2021 4:52 am
I read somewhere that NGC 4565 would look like M100 if we could see it face on.
Ann