The Sombrero Galaxy (Messier 104), is a lenticular galaxy well known for its large central bulge and prominent dust lane in its disk. This gives it the appearance of a sombrero hat.
Messier 104 is about 31 million light-years from Earth and is about a third the size of the Milky Way. At apparent magnitude of 8.0, you can observe it with a telescope, though you might need a reasonably large one.
Description
History
Pierre Méchain first observed the Sombrero Galaxy in 1781. Charles Messier recorded it a little later in his now-famous list of objects. However, it (and another 5 objects) was officially included in the catalog only in 1921.
The galaxy has interested astronomers over the years since it’s discovery.
Galactic Nucleus
The nucleus of the Sombrero Galaxy includes weakly ionized gas. Either hot, young stars found in star formation regions or active galactic nuclei could cause this ionization. In the case of Messier 104, it has a supermassive black hole in its center.
And what a massive black hole it is! In the 1990s, a research group calculated that the speed of revolution of the stars within the center of the galaxy required a mass 1 billion times that of our Sun to be present in the galactic center. This black hole is 250 times more massive that the one in the center of the Milky Way and is thus one of the most massive ever measured in any nearby galaxy!
The Sombrero Galaxy had further mysteries in store for scientists. In 2006, research groups discovered that the Sombrero Galaxy emits terahertz radiation from its nucleus. The source of the terahertz radiation remains unidentified till today.
Dust Ring
Messier 104 has a striking, symmetrical dust ring enclosing its central bulge. Most of the galaxy’s cold atomic hydrogen gas and the dust lie within this ring. Studies reveal the dust ring to be the primary site of star formation within this galaxy.
This dust ring is my favorite part of the Sombrero Galaxy. I like how the light from the galaxy core illuminates it from the back. The detail contrasts with the rather featureless central bulge.
Acquisition and Image Processing
I captured this LRGB image with 30s Luminance subs and 60s RGB subs. LRGB images are broadband in nature and far more susceptible to light pollution and moonlight. Hence, I had to wait for moonless nights and for M104 to rise higher in the night sky.
The Pixinsight workflow I used was:
Luminance:
- Dynamic Background Extraction (DBE)
- Deconvolution
- Sharpening (Multiscale Median Transform)
- Noise Reduction (TGV)
- Masked Stretch
RGB:
- Dynamic Background Extraction (DBE)
- Automatic Background Extraction (ABE) – This seemed to work quite well in tandem with DBE in managing the color gradient I was facing after combination.
- Noise Reduction (TGV)
- Masked Stretch
LRGB:
- Photometric Color Calibration
- Color Saturation (increase saturation of galaxy and stars, and de-saturate the background – a little trick to manage the color gradients)
- Selective Color Noise Reduction (SCNR – Green reduction)
Considering my last few LRGB images were not very good at all, I was quite pleased with how the Sombrero Galaxy turned out.