Spiral galaxies are common in the universe. This nearly face-on example from the Hubble Telescope is found 111 million light-years away in the constellation Centaurus. Most of them swirl in a direction one might intuitively assume. This one appears to go in a counter-clockwise direction. Analysis using images by the Hubble Telescope show the outer arms moving clockwise instead. Evidence suggests it consumed a smaller companion galaxy which disturbed its rotation.
Drs. Ron Buta and Gene Byrd from the University of Alabama, Tuscaloosa, and Tarsh Freeman of Bevill State Community College in Alabama, observed NGC 4622 in ultraviolet, infrared, and blue and green filters. Their findings were presented to the American Astronomical Society in January 2002.
There are billions of billions of galaxies in the known universe. They are oriented in countless different ways. A small fraction show their full face toward Earth, while some show an edge-on view. This first example is a nearly face-on view of NGC 4414. Imaged by the Hubble Telescope in 1995, it lies about 60 million lt-yr from Earth. Only about half of the galaxy fit into the detector of Hubble due to its large size.
Three red, green, and blue filtered greyscale images were used to make my color version of this galaxy. The center region is densely populated with older yellow and red stars. This is typical of spiral galaxies. The outer regions are less populated and include younger blue stars. The galaxy has a lot of dust mixed into the spiral arms as evidenced by the dark clouds and bands in silhouette against the bright star glow.
This next galaxy is a nearly perfect edge-on view of NGC 4013. The very bright light source at the heart of this galaxy is actually a star in the foreground much closer than the galaxy. It is part of our Milky Way galaxy and just happens to be in alignment. NGC 4013 is about 55 million lt-yr away in the direction of Ursa Major, the Big Dipper. If we could see it face-on, it would have a spiral shape similar to NGC 4414 above. What stands out clearly in this edge-on view is the dark band of dust cutting across the width of the galaxy. A few blue stars show in the upper right. They are in an outer band and less obscured by the dust.
In April 2019, astronomers with the Event Horizon Telescope EHT released the most detailed image of the region near a black hole in the large elliptical galaxy M87. This image was the first view inside the core of a galaxy showing the extremely energetic spinning disc, or donut, of material and radiation surrounding the invisible black hole at the center. Material falling into the black hole disappears within this horizon. Not even light can escape. This black hole is about 55 million light-years from us and has a mass 6.5 million times that of our Sun.
We are not seeing the black hole. We are aware of the absence of anything visible in the center. That is where the black hole is located. I invite you to read my previous non-technical post about this story.
In April 2021, new findings from multiple radio, optical, X-ray, and gamma-ray telescopes were shared revealing greater detail about the broader surroundings and processes taking place in the vicinity of galaxy M87. The telescopes are ground based and some are space based. They observed in wavelengths from long radio waves of many meters, the more familiar shorter waves of the optical spectrum, and in extremely short X-ray and gamma-ray wavelengths. Such broad coverage will give scientists greater insights into the dynamics near black holes and aid their understanding of Einstein’s General Theory of Relativity.
In the far southern skies is the constellation Piscis Volans, the flying fish. Within Volans lies this galaxy NGC 2442. It is distorted from the more common spiral shape into a meathook appearance. The unusual shape is likely the result of a close encounter with another galaxy not in the field of view. The galaxy lies about 50 million light years away. Visible are darkened dust lanes, young blueish star clusters, and reddish star forming regions. More views are from Astronomy Picture of the Dayhere, here, and here.
I tried my hand at producing a color version of the Meathook galaxy using 3 greyscale images from the Hubble Telescope. The process is described in this previous post. The Hubble images provide rich detail.
Spiral galaxies are common in the universe. This example of the Pinwheel Galaxy M101 from the Hubble Telescope is found in Ursa Major, the Big Dipper.
About ⅔ of the spiral galaxies also have a feature in the center called a bar. This next example, also from Hubble, is known as NGC 1300. Some bars are very long and pronounced, as this one. Other galaxies have a bar that is quite short.
Notice in each galaxy the blue cast in the spiral arms. It comes from the glow of relatively young stars. Older stars tend to glow white, yellow, or orange. The vein-like structures are regions darkened by the absorption of dust.