M97 - Owl Nebula
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Messier 97, also known as the Owl Nebula, is a planetary nebula located about 2,030 light-years from Earth in the constellation Ursa Major. Its age is estimated to be around 6,000 to 8,000 years. This object has an approximately circular cross-section, featuring a subtle internal structure of three main concentric shells, with the outermost shell about 20–30% larger than the inner one. The nebula’s owl-like appearance—primarily the dark patches resembling eyes—results from the inner shell’s barrel-shaped structure, tilted at a 45° angle relative to our line of sight.
To find the nebula in the night sky, look southeast of the Big Dipper’s bowl, near the star Merak (Beta Ursae Majoris, β UMa). From there, M97 lies just over 2.5 degrees to the southeast, toward the star Phecda (Gamma Ursae Majoris, γ UMa).
Observations
June 26, 2024, around midnight – Jaworzno (Poland), garden
urban conditions, high level of light pollution
The Owl Nebula is a relatively faint object and cannot be observed with the naked eye, even under the best conditions. For visual observations, a small telescope or large binoculars (20×80) will show it as a faint, featureless patch. To see the nebula’s more distinctive features—dark spots resembling an owl’s eyes, from which the nebula gets its name—a telescope with a 15–20 cm (6–8 inch) aperture or larger is required. However, the best way to observe this nebula, as with other deep-sky objects, is through long-exposure astrophotography (Photo 1).
The nebula’s mass is relatively small, with a mass of only 0.13 solar masses (0.13 M☉). It is primarily composed of hydrogen (H), helium (He), nitrogen (N), oxygen (O), and sulfur (S), with a density of less than 100 particles per cubic centimeter. Its outer radius is approximately 0.91 light-years and is expanding at a speed of 27–39 km/s.
The central star, with an apparent magnitude of 14m, ejected a large portion of its material during the final stages of its evolution, forming the nebula. It has since transformed into a white dwarf with a mass of 55–60% that of the Sun, yet it is several times brighter and hotter than our star. Nuclear fusion no longer takes place within the white dwarf, so it will gradually cool as it radiates its remaining energy.
Photo 1 Parameters:
- Total exposure time: 70 minutes (stack of 70 RAW frames at 60s each, using an appropriate number of dark, bias, and flat frames)
- Canon EOS 60D
- ISO: 1500
- Newton telescope (150/750), 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
Futher readings:
- Stanghellini L., Shaw R. A., Villaver E., The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale, The Astrophysical Journal, 2008, 689(1), str. 194-202
- Guerrero M. A., and Chu Y.-H., Manchado A., Kwitter K. B., Physical Structure of Planetary Nebulae. I. The Owl Nebula, The Astrophysical Journal, 2003, 125(6): str. 3213-3221
- Jones K. G., Messierś Nebulae and Star Clusters (2nd ed.), Cambridge University Press, 1991, str. 277-279,
Marek Ples