M57 - Ring Nebula
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The Ring Nebula, designated as number 57 in Messier’s catalog (M57), is one of the most well-known planetary nebulae. It is located within our own galaxy.
It is widely accepted that the nebula was discovered in January 1779 by the French astronomer Antoine Darquier de Pellepoix. However, recent analyses suggest that Messier may have observed it first—at the end of January—while Darquier likely observed it in mid-February, as he acknowledged in a letter to Messier.
In the celestial sphere, M57 lies within the boundaries of the constellation Lyra—one of the most prominent constellations of the northern sky, ranking fifty-second in size. It is visible in Poland from spring through autumn.
Lyra has been known since ancient times—its name is of Greek origin and is associated with the myth of Orpheus. According to legend, Orpheus was a singer endowed with divine talent, who accompanied himself on a lyre given to him by his father Apollo, which had been invented and built by Hermes using a turtle shell. Orpheus’ music and singing were said to enchant all living creatures—even the guardians of the underworld, allowing Orpheus to enter and attempt to rescue his wife, Eurydice. Even Hades agreed to release Eurydice on the condition that Orpheus not look back while ascending to the surface. However, Orpheus forgot this rule and, eager to see his beloved, looked back, losing her forever. Heartbroken, Orpheus wandered the Earth, playing his lyre. He was eventually torn apart and thrown into a river by the Maenads (Bacchantes), most likely as revenge from Dionysus for refusing to participate in his festival. His lyre and head, which continued to sing, drifted to the island of Lesbos. There, Orpheus’ remains were buried, while his lyre was placed among the stars by the Muses.
The constellation’s distinctive parallelogram of stars resembles the frame of a celestial instrument. The alpha star of Lyra (α Lyr) is Vega, the fifth brightest star in the night sky, with an apparent magnitude of 0.03m. Vega is a relatively nearby white main-sequence star of spectral type A0, located just 25 light-years from Earth. It is about 37 times more luminous than the Sun, with an average surface temperature of 9,500°C. Its mass is approximately 2.15 M☉, and its age is estimated to be between 471 and 700 million years. Vega is roughly halfway through its main-sequence phase of hydrogen-to-helium fusion. In about 650 million years, it will end its life as a white dwarf, after first expanding into a red giant or becoming a Cepheid variable. It was also one of the first stars found to have a cold dust disk, with a temperature of about −180°C. The disk’s complex structure, with a distinct inner boundary, suggests that Vega may host a planetary system. Observations using a coronagraph in 2005 limited the maximum mass of orbiting bodies to 5–10 times the mass of Jupiter.
The other four stars forming the characteristic trapezoid are of third and fourth magnitude. They are, in order: Sulafat (γ Lyr), Sheliak (β Lyr), Delta (δ2 Lyr), and Zeta (ζ Ly). In Photo 1, I have also marked the location where the Ring Nebula can be found.
Observations
July 6, 2021 – Jaworzno (Poland), garden
urban conditions, high level of light pollution
Despite some cloud cover, the sky cleared around midnight, allowing for observations of the Lyra region. The Ring Nebula has small angular dimensions (approximately 1.4′ by 1.0′) and an apparent magnitude of 8.8m, making it invisible to the naked eye. Under dark skies, it can be seen as a small, fuzzy spot with good binoculars. A suitable telescope reveals its shape, while photographic imaging techniques capture its intricate structure and vibrant colors.
Current estimates place the Ring Nebula at a distance of approximately 2,300 light-years from Earth, and it is moving toward us at a speed of 19.2 km/s. Its observed angular dimensions of 1.4′ by 1.0′ correspond to actual dimensions of 1.9 by 1.3 light-years at that distance. By combining its current dimensions and expansion speed, we can estimate the nebula’s age to be between six and eight thousand years.
The mass of the nebula’s material is approximately 0.2 M☉, with a density of about 10,000 particles per cubic centimeter. Spectroscopic studies have revealed the following atomic abundances in this region of interstellar space, relative to each atom of fluorine (F):
- 4,250,000 atoms of hydrogen (H)
- 337,500 atoms of helium (He)
- 2,500 atoms of oxygen (O)
- 1,250 atoms of nitrogen (N)
- 375 atoms of neon (Ne)
- 225 atoms of sulfur (S)
- 30 atoms of argon (Ar)
- 9 atoms of chlorine (Cl)
The central region of the nebula appears darker because most of its radiation is emitted in the ultraviolet range. The inner regions of the ring emit green light due to ionized oxygen, while the outer red regions owe their color to hydrogen. The central star is difficult to observe, but it is possible with appropriate equipment.
The term "planetary nebula" can be misleading, as these nebulae have no real connection to planets. The name is historical—early astronomers, lacking knowledge about the nature and formation of these objects, named them based on their visual appearance, which resembled the disks of distant planets like Neptune.
Planetary nebulae form during the final stages of the evolution of stars with masses between 1 and 8 M☉. The star's core collapses, becoming a white dwarf with a mass of up to about 1.4 M☉. During this process, most of the star's material is ejected into space, enriching the interstellar medium. The spherical, thin shell around the star forms when dense, slow stellar winds are compressed by faster, less dense winds that follow. When enough material accumulates and the central star becomes sufficiently hot, the spherical shell—located about half a light-year from the star—begins to glow, becoming visible as a nebula. The temperature within this gaseous shell typically reaches around 10,000°C. Planetary nebulae continuously expand, and within a relatively short astronomical timescale of about 10,000 years, their material disperses into the interstellar medium, eventually ceasing to emit light and becoming invisible.
Photo 1 Parameters:
- Total exposure time: 30 seconds (single shot)
- Canon EOS 60D
- ISO: 1500
- Lens: zoom type
- 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
Photo 2 Parameters:
- Total exposure time: 30 minutes (stack of 15 RAW frames at 120s each, using an appropriate number of dark, bias, and flat frames)
- Canon EOS 60D
- 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
Marek Ples