M81 - Bode's Galaxy
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Bode’s Galaxy, also known as M81, is a spiral galaxy located in the constellation Ursa Major. It was discovered in 1774 by the German astronomer Johann Elert Bode, from whom it derives its popular name.
M81 is one of the brightest galaxies in the night sky, making it a relatively accessible target for amateur astronomers equipped with telescopes. It lies approximately 12 million light-years from Earth, which, on the cosmic scale, makes it a relatively close neighbor.
One of the most intriguing aspects of Bode’s Galaxy is its gravitational interaction with the neighboring Cigar Galaxy (M82). This gravitational interaction led to a cascade of events in the past, resulting in intense star formation in both galaxies. M81 also contains an active galactic nucleus (AGN), housing a supermassive black hole with a mass of approximately 70 million solar masses.
Bode’s Galaxy is part of a galactic group known as the M81 Group, which comprises about a dozen galaxies.
Observations
May 25, 2024, around midnight – Jaworzno (Poland), garden
urban conditions, high light pollution
Despite a few lingering clouds along the western horizon, observations were possible in the region of the Big Dipper (Ursa Major). Bode’s Galaxy is sometimes cited as one of the most distant astronomical objects visible to the naked eye. However, it must be noted that this is only possible under exceptional conditions and with excellent eyesight, as its apparent magnitude is 6.9m. The galaxy’s full beauty is best revealed through long-exposure photography (Photo 1).
As shown, Bode’s Galaxy is a classic example of a spiral galaxy, similar to our Milky Way. It features well-defined spiral arms filled with young, hot stars and star-forming regions. The central part of M81 contains a prominent galactic nucleus, where the supermassive black hole resides, with a mass of approximately 70 million solar masses.
Observing M81 provides valuable insights into the structure and evolution of spiral galaxies, as well as processes related to star formation and large-scale interactions between galaxies. For astronomers—both amateur and professional—M81 remains one of the most captivating objects in the night sky.
Photo 1 Parameters:
- Total exposure time: 80 minutes (stack of 160 RAW frames at 30s each, using an appropriate number of dark, bias, and flat frames)
- ISO: 1600
- Maksutov-Cassegrain telescope (100/1400), prime focus exposure
- A filter was used to reduce the effects of artificial light pollution and atmospheric glow
- Mount: equatorial mount with tracking, aligned using the drift method and controlled by a custom-built system.
Further readings:
- Devereux N., Ford H., Tsvetanov Z., Jocoby J., STIS Spectroscopy of the Central 10 Parsecs of M81: Evidence for a Massive Black Hole, The Astronomical Journal, 2003, 125(3), str. 1226-1235
- Karachentsev I. D., The Local Group and Other Neighboring Galaxy Groups, The Astronomical Journal, 2005, 129(1), str. 178-188
- Yun M. S., Ho P. T. P., Lo K. Y., A high-resolution image of atomic hydrogen in the M81 group of galaxies, Nature, 1994, 372(6506), str. 530-532
Marek Ples