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In this answer as well as this one, I've linked to New Jersey Institute of Technology's Dr. Dale Gary's nicely-written Physics 728 Radio Astronomy; Lecture #1 notes where I can see the image below. It links to Gizmodo.au's New South African Telescope Releases Epic Image Of The Galactic Centre.

I have heard of the Meerkat array earlier (Which 16 antenna locations are used for the MeerKAT radio image recently announced?), but I am wondering how to read further about this spectacular image. What is the scale for example? How would it look pasted into the arc of the Milky Way; just a tiny patch of a few arc-minutes, or several tens of degrees?

How will this compare to the radio image of Sag A* that we will see in the next day or two?

Also, if anyone knows, what are those spiky arcs sticking up, and those puff-ball things on the left?


Source: Gizmodo "The black hole at the centre of the Milky Way and filaments." Credit: SARAO, click for full size.

Meerkat Epic Image Of The Galactic Centre

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    $\begingroup$ Found a few details on Apod, field of view is about 2 degrees across. apod.nasa.gov/apod/fap/holdMeerKAT.html $\endgroup$ – MichaelB76 Apr 9 at 10:46
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    $\begingroup$ That APOD image has some labels which appear when you mouse over it. $\endgroup$ – Mike G Apr 9 at 16:49
  • $\begingroup$ @MikeG oh that is so cool! If you mouse-over so that the annotated JPEG is shown, and then open in a new window or save to disk, you can have the annotated version saved. i.stack.imgur.com/Ud07k.jpg A little more work and one could make a GIF with the labels blinking on and off like an old fashioned neon sign. Since that addresses more aspects of my question that the current answer doesn't, consider posting that as a second answer? $\endgroup$ – uhoh Apr 9 at 16:54
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LaRosa et al 2000 present a 90 cm VLA image and catalog of sources near the galactic center. Here is their schematic diagram with the 2°x1°, 18-33 cm band MeerKAT image region highlighted.

Schematic of galactic center in 90 cm

The compact source Sgr A* is a small dot within the bright, pear-shaped blob Sgr A right of center. Recent millimeter VLBI images (Issaoun et al 2019) indicate a width on the order of 200 μas, or 1/7000 of a pixel in the image you uploaded.

The bright pair of blobs left of center, Sgr B1 and Sgr B2, are massive molecular clouds.

Most of the bubble shapes are either supernova remnants (SNRs) or H II regions ionized by UV-bright young stars. The far left pair Sgr D has one of each.

The various non-thermal filaments (NTFs) align with the local magnetic field and emit synchrotron radiation but are not well understood otherwise. The bundle of filaments near the center of the image are known as the galactic center radio arc (GCRA) or just the Arc.

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  • $\begingroup$ Excellent graphic, this is all news to me, thank you! I didn't know Sgr had B's, C's, D's and E's or any of these other strange features! I'm seeing our galaxy in a whole new light! (pardon the pun) $\endgroup$ – uhoh Apr 9 at 22:52
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This article by the Bad Astronomer does a good job of explaining what is visible in the MeerKAT image.The field of view is one by two degrees.

Sa A* is the bright area right of centre, the arc to the left of that may be associated with the Arches cluster. The two bright joined blobs left of that are molecular clouds and further left are some supernova remnants. The filaments scattered over the image are somewhat mysterious but may be aligned with star-forming regions.

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  • $\begingroup$ "What is the scale for example? How would it look pasted into the arc of the Milky Way; just a tiny patch of a few arc-minutes, or several tens of degrees?" Also, do the molecular clouds have names? A good Stack Exchange answer will include all of the main information within the post itself rather than to rely on a link or leaving part of the answer in as comment under the question. Thanks! $\endgroup$ – uhoh Apr 9 at 11:43

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