How big is Andromeda really? #2, 



    
        

            Giuseppe Donatiello

How big is Andromeda really? #2

How big is Andromeda really? #2, 



    
        

            Giuseppe Donatiello

How big is Andromeda really? #2

Equipment

Imaging Telescopes Or Lenses
Pentacon MC Auto 200mm f/4 · Zenit TAIR-3S 300mm f/4.5
Imaging Cameras
(DIY) Full Range 3MP Cooled CMOS · Canon EOS 4000D
Mounts
Synta EQ5 · Avalon Instruments M-Zero Fast Reverse
Software
Sharcap · Auriga Imaging RegiStar 1.0.9 · Corel PaintShop Pro X8
Guiding Telescopes Or Lenses
(DIY) Achro 80/400

Acquisition details

Basic astrometry details

Astrometry.net job: 4003108

Resolution: 4128x3302

Locations: Home site, Oria, Brindisi, Italy; Piano Visitone - Pollino, Rotonda, Potenza, Italy

Data source: Traveller

Description

How big is Andromeda really?

The Andromeda Galaxy (Messier 31), at 2.5 million light-years (770 kiloparsecs) is the nearest major galaxy to the Milky Way. For this reason, excluding the satellites of the Milky Way, it is the galaxy with the largest apparent size. But how big is it really?

Limited to the galactic disk, as much as 12 full moons, as I reported. However, if we also consider the faintest regions that can be recorded in very deep images, the extension is not less than 25 full moons, without considering the complex of tidal structures.

In this special elaboration, the field stars were removed, using a script of my invention, and the signal of the peripheral regions was increased. As we can see the environment external to the galactic disk (shown in superimposition to the inverted image), manifests a rather unsuspected scenario.

A "normal" version, so to speak, is here:

https://astrob.in/zq18g6/0/

Comments

Histogram

How big is Andromeda really? #2, 



    
        

            Giuseppe Donatiello