Free Astronomy Magazine July-August 2021

22 Accompanying Messier 106 is a pair of dwarf galaxies belonging to the same galaxy group. The loose collection of stars and dust visible in the bottom-right of this image is the small irregular galaxy NGC 4248. An- other small galaxy —UGC 7356 — lies to the lower-left of Messier 106 and is dwarfed by its larger neighbor. Messier 106 and its com- panions are framed by a variety of objects, from foreground stars to background galax- ies. Stars from our own galaxy stud the image, easily identified by the criss-cross dif- fraction patterns surrounding them. In the background, distant galaxies litter the image, some of them visible through the tenuous disk of Messier 106. As well as being a striking subject for astro- nomical images, Messier 106 has been in- strumental in measuring the scale of the Universe. Astronomers measure distances in the Universe using an interconnected chain of measurements called the cosmic distance ladder, with each rung of the ladder allow- ing measurements of more and more dis- tant objects. Calibrating these measure- ments requires objects with a known bright- ness — such as pulsating stars known as Cepheid variables. Measurements of the Cepheids in Messier 106 have allowed astronomers to calibrate Cepheids elsewhere in the Universe — help- ing them to measure the distances to other galaxies. This image was one of the last to be taken with the Mosaic camera before the installation of the Dark Energy Spectro- scopic Instrument (DESI), a project of the De- partment of Energy’s Office of Science and Lawrence Berkeley National Laboratory. Unrivaled view of galaxy Messier 106 T his celestial snapshot captures the majesty of the spiral galaxy Messier 106, also known as NGC 4258. The image is arguably the best yet captured of the entire galaxy. Obtained using the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory, a Program of NSF’s NOIRLab, this image shows not only the glowing spiral arms, wisps of gas, and dust lanes at the core of the galaxy but also the leisurely twisting bands of stars at its outer edges. A popular target for amateur astronomers, Messier 106 can be spotted with a small tel- escope in the constellation Canes Venatici. Messier 106 is similar in size and luminosity to our galactic neighbor the Andromeda Galaxy, but it lies 10 times farther away — more than 20 million light-years from Earth. Though the galaxy measures more than 130,000 light-years from edge to edge, the vast distance between it and the Milky Way renders Messier 106 minuscule when seen from here. Its size in the night sky — if it were visible to the naked eye — is less than that of a penny held at arm’s length! De- spite its tranquil appearance, Messier 106 has an unusually energetic inhabitant. The supermassive black hole at the heart of the galaxy — which is about 40 million times as massive as our Sun — is particularly active. As well as consuming vast amounts of gas and dust, the spinning black hole has warped the surrounding disk of gas, churn- ing up vast amounts of material. This process has created the bright, red streamers of gas emanating from the heart of Messier 106, visible in the center of this image. by NOIRLab - Amanda Kocz !