APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Comments and questions about the APOD on the main view screen.
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APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by APOD Robot » Tue Mar 31, 2020 4:06 am

Image The Galactic Center from Radio to X-ray

Explanation: In how many ways does the center of our Galaxy glow? This enigmatic region, about 26,000 light years away toward the constellation of the Archer (Sagittarius), glows in every type of light that we can see. In the featured image, high-energy X-ray emission captured by NASA's orbiting Chandra X-Ray Observatory appears in green and blue, while low-energy radio emission captured by SARAO's ground-based MeerKAT telescope array is colored red. Just on the right of the colorful central region lies Sagittarius A (Sgr A), a strong radio source that coincides with Sgr A*, our Galaxy's central supermassive black hole. Hot gas surrounds Sgr A, as well as a series of parallel radio filaments known as the Arc, seen just left of the image center. Numerous unusual single radio filaments are visible around the image. Many stars orbit in and around Sgr A, as well as numerous small black holes and dense stellar cores known as neutron stars and white dwarfs. The Milky Way's central supermassive black hole is currently being imaged by the Event Horizon Telescope.

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by Ann » Tue Mar 31, 2020 5:57 am

I don't agree that today's APOD shows the Galactic center from radio to X-ray; rather, it shows the Galactic center in radio and X-ray.

So I thought I would post a few pictures that show the Galactic center in other wavelengths, too.






















Infrared/visible light comparison of VISTA’s
gigapixel view of the centre of the Milky Way. ESO.
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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by Boomer12k » Tue Mar 31, 2020 10:00 am

It is actually the other wavelengths we DON'T see...

Space is not empty... it is full of stuff... like Radiation and Emanation of various types of Energy. Many manifestations.

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by orin stepanek » Tue Mar 31, 2020 11:45 am

GalCenterRadXray_NASA_1080.jpg
Boomer12k wrote:
Tue Mar 31, 2020 10:00 am
It is actually the other wavelengths we DON'T see...

Space is not empty... it is full of stuff... like Radiation and Emanation of various types of Energy. Many manifestations.

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Yes it is full of stuff; but it is also empty :mrgreen: Lots of distance between the stuff! It is good that there is a lot of stuff between the emptiness! 🚀
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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by BDanielMayfield » Tue Mar 31, 2020 12:58 pm

I wonder, how bright the core region of our galaxy would appear if all the interstellar gas and dust between us and it where somehow removed?

Since there are other galaxies (the so called "red and dead") that appear to be clear of interstellar material we know that a galaxy can use up and/or have it's dust and gas swept away. How long is it expected until the Milky Way reaches such a cleared state?
Last edited by BDanielMayfield on Tue Mar 31, 2020 1:02 pm, edited 1 time in total.
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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by neufer » Tue Mar 31, 2020 1:01 pm

Click to play embedded YouTube video.

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by Janester » Tue Mar 31, 2020 2:02 pm

I am curious how long these exposures were?

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by jisles » Tue Mar 31, 2020 2:16 pm

Strictly, it's Sgr A, not Sag A. The official three-letter abbreviation for the constellation Sagittarius is Sgr, to distinguish it from Sagitta, which is Sge (short for the genitive Sagittae).

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by Ann » Tue Mar 31, 2020 2:23 pm

jisles wrote:
Tue Mar 31, 2020 2:16 pm
Strictly, it's Sgr A, not Sag A. The official three-letter abbreviation for the constellation Sagittarius is Sgr, to distinguish it from Sagitta, which is Sge (short for the genitive Sagittae).

John
Strictly speaking, it is Sgr A*, not Sgr A. :wink:

But you are right about Sagitta. Normally, the name of a constellation followed by a letter would mean a variable star, but the variables begin on the letter R, so no Sag A or Sge A. But you can read about Sge R here. It is a bright old thing.

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by Ann » Tue Mar 31, 2020 2:24 pm

neufer wrote:
Tue Mar 31, 2020 1:01 pm
Click to play embedded YouTube video.

I saw Metropolis for the first time only a couple of weeks ago. I thought it was really interesting.

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by jisles » Tue Mar 31, 2020 2:29 pm

Ann,

Sgr A is correct for Sgr A, and Sgr A* is correct for Sgr A*. The first is the radio source, and the second is the black hole.

John

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by jisles » Tue Mar 31, 2020 2:36 pm

Also that variable star is R Sge, not Sge R.

John

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by bystander » Tue Mar 31, 2020 2:39 pm

Ann wrote:
Tue Mar 31, 2020 2:23 pm
jisles wrote:
Tue Mar 31, 2020 2:16 pm
Strictly, it's Sgr A, not Sag A. The official three-letter abbreviation for the constellation Sagittarius is Sgr, to distinguish it from Sagitta, which is Sge (short for the genitive Sagittae).

Strictly speaking, it is Sgr A*, not Sgr A. :wink:

Strictly speaking, Sgr A contains Sgr A* as well as Sgr A East and Sgr A West.
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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by sillyworm 2 » Tue Mar 31, 2020 3:11 pm

Fascinating.I definitely want to know more about these filaments,etc.

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by heehaw » Tue Mar 31, 2020 4:39 pm

26,000 light years away. For a moment I was shocked. Because as a professional astronomer I use parsecs, not light years, so the number briefly stunned me! But! The simple truth of the matter is that 'light year' is a FAR better measure of large astronomical distances, than is silly parsecs. For it, obviously, tells you how long light has to travel to get here! Parsecs tells you - wait for it! - how big Earth's orbit around the Sun would appear from that distant location. Given what we see in that fabulous photograph, there are NO intelligent creatures there to CARE how big Earth's orbit appears to be from their location. Abolish parsecs!

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by Ann » Tue Mar 31, 2020 4:47 pm

heehaw wrote:
Tue Mar 31, 2020 4:39 pm
26,000 light years away. For a moment I was shocked. Because as a professional astronomer I use parsecs, not light years, so the number briefly stunned me! But! The simple truth of the matter is that 'light year' is a FAR better measure of large astronomical distances, than is silly parsecs. For it, obviously, tells you how long light has to travel to get here! Parsecs tells you - wait for it! - how big Earth's orbit around the Sun would appear from that distant location. Given what we see in that fabulous photograph, there are NO intelligent creatures there to CARE how big Earth's orbit appears to be from their location. Abolish parsecs!
Hear, hear! :clap:

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by ta152h0 » Tue Mar 31, 2020 5:08 pm

Wait until Andromeda crashes into this party someday! Long after I'm gone. pass the ice cold one.
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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by Chris Peterson » Tue Mar 31, 2020 5:29 pm

heehaw wrote:
Tue Mar 31, 2020 4:39 pm
26,000 light years away. For a moment I was shocked. Because as a professional astronomer I use parsecs, not light years, so the number briefly stunned me! But! The simple truth of the matter is that 'light year' is a FAR better measure of large astronomical distances, than is silly parsecs. For it, obviously, tells you how long light has to travel to get here! Parsecs tells you - wait for it! - how big Earth's orbit around the Sun would appear from that distant location. Given what we see in that fabulous photograph, there are NO intelligent creatures there to CARE how big Earth's orbit appears to be from their location. Abolish parsecs!
Parsecs make sense as a derived unit when you're working with something like Gaia data. But definitely- in the big scheme of things a light year is a much better measurement. The only thing that would make it perfect would be replacing "year" with some more universal interval of time- one that anybody in the Universe would recognize. But at least, year ties back to seconds, and seconds depend upon a universal physical property. Quite unlike parsecs, which depend upon an archaic Babylonian number system and the size of Earth's orbit!
Chris

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by richard schumacher » Tue Mar 31, 2020 7:13 pm

What is the width of this scene at the distance of the galactic center?

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by neufer » Tue Mar 31, 2020 8:34 pm

Chris Peterson wrote:
Tue Mar 31, 2020 5:29 pm

Parsecs make sense as a derived unit when you're working with something like Gaia data. But definitely- in the big scheme of things a light year is a much better measurement. The only thing that would make it perfect would be replacing "year" with some more universal interval of time- one that anybody in the Universe would recognize. But at least, year ties back to seconds, and seconds depend upon a universal physical property. Quite unlike parsecs, which depend upon an archaic Babylonian number system and the size of Earth's orbit!
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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by felix_wegerer » Wed Apr 01, 2020 9:30 am

Seeing images in wavelengths our eye can't see is always amazing.

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by TheZuke! » Wed Apr 01, 2020 1:29 pm

richard schumacher wrote:
Tue Mar 31, 2020 7:13 pm
What is the width of this scene at the distance of the galactic center?
Good question, but the answer is not easy, because time and space are compressed by the black hole,
so while it may "look" to be 2^x furlongs wide, there may be an infinite number of furlongs, barleycorn lengths or centons between any two points.

I am sure our good friend neufer can produce an equation that will lead you toward an approximation.

:ssmile:

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by neufer » Wed Apr 01, 2020 2:08 pm

TheZuke! wrote:
Wed Apr 01, 2020 1:29 pm
richard schumacher wrote:
Tue Mar 31, 2020 7:13 pm

What is the width of this scene at the distance of the galactic center?
Good question, but the answer is not easy, because time and space are compressed by the black hole,
so while it may "look" to be 2^x furlongs wide, there may be an infinite number of furlongs, barleycorn lengths or centons between any two points.

I am sure our good friend neufer can produce an equation that will lead you toward an approximation.
  • One degree at 26,000 light years ~ 450 light years:
https://apod.nasa.gov/apod/ap081110.html wrote:
Explanation: The central region of our Milky Way Galaxy is a mysterious and complex place. Pictured here in radio and infrared light, the galaxy's central square degree is highlighted in fine detail. The region is known as the Central Molecular Zone. While much of the extended emission is due to dense gas laced with molecules, also seen are emission nebulas lit up by massive young stars, glowing supernova remnants, and the curving Galactic Center Radio Arc in purple. The identity and root cause for many other features remains unknown. Besides a massive black hole named Sgr A*, the Galactic Center houses the galaxy's most active star forming region. This image is not just interesting scientifically. It's esthetic beauty won first prize this year in the AUI/NRAO Image Contest.
Art Neuendorffer

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by Chris Peterson » Wed Apr 01, 2020 2:13 pm

TheZuke! wrote:
Wed Apr 01, 2020 1:29 pm
richard schumacher wrote:
Tue Mar 31, 2020 7:13 pm
What is the width of this scene at the distance of the galactic center?
Good question, but the answer is not easy, because time and space are compressed by the black hole,
so while it may "look" to be 2^x furlongs wide, there may be an infinite number of furlongs, barleycorn lengths or centons between any two points.

I am sure our good friend neufer can produce an equation that will lead you toward an approximation.
I don't find any reference as to the angular size of the image, but I imagine Art's suggestion of a degree is in the ballpark, meaning that it's reasonable to think we're looking at something on the order of 100 light years across. That's far too large for the black hole to have any visible impact on either time or space. We're not seeing any distortion in this image from the black hole.
Chris

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Re: APOD: The Galactic Center from Radio to X-ray (2020 Mar 31)

Post by MarkT » Sun Apr 05, 2020 12:27 pm

Image