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Draco Dwarf Galaxy, 





    
        

            Jerry Macon
Draco Dwarf Galaxy

Draco Dwarf Galaxy

Technical card

Resolution: 3892x2808

Dates:March 24, 2019March 25, 2019

Frames:
Astrodon Gen 2 L 36mm: 19x100" (gain: 99.00) -15C bin 1x1
Astrodon Gen 2 L 36mm: 15x300" (gain: 99.00) -15C bin 1x1
Astrodon Gen 2 RGB 36mm: 91x100" (gain: -20.00) bin 1x1
Astrodon Gen 2 RGB 36mm: 78x300" (gain: 99.00) -15C bin 1x1

Integration: 10.8 hours

Avg. Moon age: 19.06 days

Avg. Moon phase: 80.36%

Bortle Dark-Sky Scale: 4.00

Astrometry.net job: 2604892

RA center: 260.063 degrees

DEC center: 57.922 degrees

Pixel scale: 0.701 arcsec/pixel

Orientation: 357.812 degrees

Field radius: 0.467 degrees

Locations: Dark Star Observatory, Taos, New Mexico, United States

Data source: Own remote observatory

Remote source: Non-commercial independent facility

Description

Images from the following two scopes (piggybacked) contributed to this image:
AG12+ASI1600MM at .70 asec/pix
TV127is+ASI183MM at .75 asec/pix.
They were all registered to the best Ha image taken on the AG12.
Using L (synthetic from RGB) from the TV NP127is refractor effectively eliminates the spikes from the AG12.

This is a galaxy? Where is it? This looks like a star field or a star cluster composed entirely of small stars.
The Draco Dwarf Galaxy is the large collection of small stars occupying the central 2/3 rd of the image. So the galaxy is (visually) quite large, measuring 35' x 24', or most of this image.

Why is this a noteworthy galaxy?
We can see hundreds of individual stars widely separated. Only dwarf galaxies fairly closely orbiting the Milky Way afford the luxury of seeing individual stars on images produced with mortal equipment. Practically every star ever shown in an image taken with amateur equipment is a star located in the Milky Way. See revision B for details of where this galaxy is located in relation to the Milky Way. Its stars are all small in this image because a) the galaxy is about 10 times as far from us as the average star in the Milky Way, and b) the stars in Draco Dwarf are all old dim stars.

The Draco Dwarf is a spheroidal galaxy which was discovered by Albert George Wilson of Lowell Observatory in 1954 on photographic plates of the National Geographic Society's Palomar Observatory Sky Survey (POSS). It is part of the Local Group and a satellite galaxy of the Milky Way galaxy. The Draco Dwarf is situated in the direction of the Draco Constellation at 34.6° above the galactic plane.

Dark matter
Recently, dwarf spheroidal galaxies have become key objects for the study of dark matter. The Draco Dwarf is one which has received specific attention. Radial velocity computations of Draco have revealed a large internal velocity dispersion, suggesting large amounts of dark matter. These measurements intricate that the Draco Dwarf is the most dark matter dominated object known as of 2007.

Our galaxy is so big and heavy that more than 50 smaller galaxies revolve around it. Draco is one of the first of these galactic satellites to be seen. When Albert Wilson was examining pictures of the constellation Draco, the dragon, he noticed a faint smudge of stars. Those stars 250,000 light-years away were the Draco Dwarf.

Like the Sun, the Draco dwarf galaxy orbits the center of the Milky Way. It’s so far out, though, that it takes between a billion and two billion years to complete just one circuit. The little galaxy’s orbit is stretched out, and it’s tilted at a steep angle to the Milky Way’s disk.

The stars in the Draco galaxy are few and faint. All together, they emit less light than the single brightest star in the Milky Way. In fact, for a long time Draco was the puniest galaxy known. And it has no gas with which to make new stars, so it’s not going to get any brighter.

In recent years, though, astronomers have spotted lots of even fainter galaxies orbiting the Milky Way. So the Draco dwarf is no longer the least luminous galaxy known.
(Wikipedia)

Comments

Author

jmacon
Jerry Macon
License: Attribution Creative Commons
2284
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Revisions

  • Final
    Draco Dwarf Galaxy, 





    
        

            Jerry Macon
    Original
  • Draco Dwarf Galaxy, 





    
        

            Jerry Macon
    B

B

Galaxies within 500,000 light years of the Milky Way

Sky plot

Sky plot

Histogram

Draco Dwarf Galaxy, 





    
        

            Jerry Macon