Planetary Nebula - Ha - What are they good for ?"

 

M57 The Ring Planetary Nebula
in the constellation Lyra. Imaged by: Pip Stakkert from the JPO
using the Meade 127mm Apo Refractor and the Canon 600d DSLR

M27 The Dumbbell Planetary Nebula
in the constellation Vulpecula. Imaged by: Kurt Thrust from the JPO
using the Meade 127mm Apo Refractor and the Canon 600d DSLR

M76 The Little Dumbbell or Cork Planetary Nebula in the constellation Perseus.
Image created, curated and processed by Kurt Thrust.
Data Credit: COAST Robotic Telescope, Teneriffe.
telescope.org Open Observatories, Open University.

M97 The Owl Planetary Nebula 
in the constellation Ursa Major
Image created, curated and processed by Kurt Thrust.
Data Credit: PIRATE Robotic Telescope, Teneriffe.
telescope.org Open Observatories, Open University.

" The Observatory sponsors recently invested in RC -Astro's excellent 'NoiseXTerminator' plug in for the Affinity Photo 2.65 software, which we use as our core photo editor at the Jodrell Plank Observatory. So the team decided to test it on a selection of images we always considered 'noisy'.

Kurt also thought that Planetary Nebulae had not been featured that often in previous posts and very little had been said about these small and intriguing objects, which irrespective of their generic collective name have absolutely nothing to do with planets" - Joel Cairo CEO of the Jodrell Plank Observatory.

"Observation Report: A Comparative Study of Planetary Nebulae — M57, M27, M76, and M97

Among the most striking celestial objects captured by amateur and professional astronomers alike are the planetary nebulae — delicate, luminous shells of gas cast off by dying stars. Despite their name, these nebulae have nothing to do with planets; the term originates from their round, planet-like appearance in early telescopes. In reality, they represent a fleeting but beautiful phase in stellar evolution, a brief transition between the red giant and white dwarf stages.

Planetary nebulae mark the final breaths of Sun-like stars — those with masses up to roughly eight times that of our Sun. After spending billions of years fusing hydrogen into helium, such a star exhausts its nuclear fuel and swells into a red giant. In its unstable outer layers, pulsations and stellar winds drive away the star’s atmosphere, leaving behind an exposed core. The remnant, an intensely hot white dwarf, bathes the ejected gases in ultraviolet light, causing them to glow in intricate patterns and vivid colors. This process lasts only a few tens of thousands of years — a mere instant in cosmic time — before the nebula dissipates into the interstellar medium. One day, our own Sun will undergo this transformation, shedding its outer layers to illuminate the space once occupied by the Solar System with a faint, spectral glow.

The images presented here — of M57, M27, M76, and M97 — showcase four distinct manifestations of this same underlying process, each a variation on the theme of stellar death and renewal.

M57 — The Ring Nebula in Lyra appears as a nearly perfect oval, a smoke ring suspended against the velvet backdrop of the constellation Lyra. Its symmetry and sharply defined edges make it one of the most iconic planetary nebulae. The bright ring traces dense gas expanding at about 20 km/s, while the interior is filled with a fainter, ionized glow. The white dwarf at its heart shines with a temperature exceeding 100,000 K, illuminating the nebula like a hidden ember lighting a cloud of dust.

M27 — The Dumbbell Nebula in Vulpecula contrasts sharply with M57’s geometric simplicity. Instead of a ring, M27 displays a complex hourglass shape, the result of gas escaping along preferred directions in the star’s equatorial and polar regions. Its relatively large apparent size and brightness make it a favorite target for both observers and imagers. The vivid greens and reds often seen in photographs arise from doubly ionized oxygen and hydrogen-alpha emissions, respectively — spectral fingerprints of the nebula’s composition and excitation.

M76 — The Little Dumbbell Nebula in Perseus presents a more turbulent visage. Its bipolar structure resembles a miniature version of M27 but appears denser and more irregular, suggesting strong stellar winds or interactions between successive shells of ejected gas. Often described as one of the faintest Messier objects, M76 rewards deep exposures with intricate filaments and knots that hint at the chaotic processes shaping planetary nebulae.

Finally, M97 — The Owl Nebula in Ursa Major takes its name from the ghostly “eyes” visible in long-exposure images, dark cavities within an otherwise round shell. Its soft, diffuse glow and subtle color palette contrast with the crisp outlines of M57, giving it a tranquil, almost meditative appearance. The symmetry of M97 suggests a more isotropic mass loss, a calm exhalation of stellar material compared to the more directional outflows of M27 and M76.

Together, these four nebulae form a kind of evolutionary gallery — each a testament to the diversity of outcomes when stars of similar mass approach the end of their lives. Differences in mass, composition, rotation, and surrounding environment sculpt each nebula into a unique shape, much as individual personalities imprint themselves on human lives.

For the casual observer, planetary nebulae may seem serene and static, but in truth they are dynamic, expanding, and evolving. The gas we see today will, in a few millennia, blend into the cosmic medium, seeding new stars and planets. In this sense, planetary nebulae are not symbols of death, but of transformation — reminders that the material of stars, including that of our own Sun, ultimately returns to the galaxy to begin anew". Professor G.P.T Chat visiting astrophysicist at the JPO.

The white dwarf star at the centre of Messier27 the Dumbell Planetary Nebula

 

Cropped image from a stack captured with the Jodrell Plank Observatory's 127mm Meade Apo refractor and a 600d Canon DSLR. Credit:Kurt Thrust.

Annotated image credit: Astrometry.net

" Planetary nebulae have nothing to do with planets! Indeed they should remind us that everything in the Universe, you, me, the Observatory cat Comet and stars have finite lives. Stars, even the biggest, hottest and most short lived have lives measured in millions if not billions of years but eventually everything comes to an end.

To explain what is happening in the above image. Approximately 10,000 years ago, a medium sized star not unlike our Sun, ran out of fuel, expanded and started pulsating losing gas as it went. Over time this gas, affected by the stars magnetic field, expanded in two cone like lobes in opposing directions The nebula we see from Earth is side on with one lobe to the left and one to the right in our image. The gas shown in red is ionized hydrogen, that shown in blue is doubly ionized oxygen.

Stars are enormous balls of gas, which over time collapse under the effect of gravity until the very central core becomes so compressed and hot such that nuclear fusion of hydrogen commences. The nuclear furnace at a stars core creates an outward pressure which balances the inward pressure of gravity and all is well and 'hunky-dory'!

The larger the star the hotter it is and at higher temperatures the faster nuclear fusion consumes the hydrogen fuel. Large hot stars have shorter lives than smaller cooler stars because they use their larger reserves of fuel much much faster than their smaller cousins. 

A star's end game, when fusion can no longer provide sufficient outward pressure to resist gravity, is is only dependant upon  mass at the point of collapse.

Stars happily fusing hydrogen to create helium, and maintaining equilibrium with gravity, are said to be on the 'main-sequence'

Very cool and tiny stars, having masses less than 0.08 that of the Sun, known as brown dwarfs, never become main-sequence stars.

Stars with a mass less than 1.4 times the mass of our Sun will, after leaving the main-sequence, first expand to form cool red giants. Over time these stars will pulsate ejecting outer layers of gas. The envelope of gas becomes separated from the core. This thin shell expands and cools creating a planetary nebula.  The very hot core sits at the centre of the  planetary nebula shining for millions of years solely by the radiation of heat. The material in a white dwarf no longer undergoes fusion reactions, so the star has no source of energy. Consequently, it cannot support itself by the heat generated from fusion against gravitational collapse, but is supported only by electron degeneracy pressure, causing it to be extremely dense. In the far distant future, our Sun will expand to create a planetary nebula and a white dwarf star.

Stars with a mass between 1.4 and 3 times the mass of our Sun continue to contract under the force of gravity which overcomes the outward pressure created by electron degeneracy. The material continues to compress until the protons and electrons are squeezed into neutrons. Above a certain density and pressure, the neutrons are subject to quantum laws and become a degenerate gas. The gas has sufficient pressure to withstand the gravitational force and equilibrium is achieved. A Neutron star is thus formed.

When stars with a mass in excess of 3 solar masses run out of fuel to fuse, there is an enormous explosion, which is called a 'supernova'. Depending upon how much mass is lost in the process the core collapses to form a 'neutron star' or a 'black hole'. 

Most stuff in space spins and stars are no exception. Anything that collapses inwards and has a rotational spin, speeds up as it collapses. Neutron stars that spin are called 'pulsars'. It is thought that as many as 10% of white dwarf stars have strong magnetic fields associated with spin and density".-  Karl Segin outreach coordinator at the Jodrell Plank Observatory.

One clear night in July 2017

Widefield image of the Western Veil

Enlarged detail of NGC 6970 Western Veil Nebula 'The Witches Broom' Detail

" After many poor weather nights at the Jodrell Plank Observatory, we have finally benefitted from some clear night skies. On the night of the 31st of July and the morning of the 1st of August we managed to have the 127mm. Meade Apo-Refractor operational for four hours - taking images of NGC6970, Messier15 and Messier 27. Today my old chum Pip Stakkert has been busy with the imaging team preparing these deep sky images" - Kurt Thrust - current Director of the Jodrell Plank Observatory.

"Ten thousand years ago or more, our ancestors looking up into the constellation Cygnus the Swan will have seen a bright light as a star exploded in a supernova. The veil nebula  is the shock wave from that explosion which is ploughing through the instellar medium. Ionised hydrogen and oxygen can be seen glowing in different colours. The 'Witches Broom'spans about 35 light years and is approximately 1400 light years away. The bright star is 52 Cygni and although it appears linked to the nebula has nothing to do with the original supernova". - Pip Stakkert - Imaging Team Leader

The Eastern Veil imaged from the Jodrell Plank Observatory back in 2015

Messier 15 in the constellation Pegasus

 

Messier 15 Globular Star cluster

"M15 is about 33,600 light-years from Earth, and 175 light years in diameter. It has an absolute magnitude of -9.2, which translates to a total luminosity of 360,000 times that of the Sun. Messier 15 is one of the most densely packed globulars known in the Milky Way galaxy. Its core has undergone a contraction known as 'core collapse' and it has a central density cusp with an enormous number of stars surrounding what may be a central black hole.
Home to over 100,000 stars, the cluster is notable for containing a large number of variable stars (112) and pulsars (8), including one double neutron star system, M15 C. M15 also contains Pease 1, the first planetary nebula discovered within a globular cluster in 1928. Just three others have been found in globular clusters since then". Credit: Wikipedia

Widefield image of the Dumbell Nebular M27 in the constellation Vulpecula 'The Fox'

Planetary Nebula Messier 27

Final enlargement and colour adjustments to bring out the central 'knots' and the 'white dwarf' star more or less in the centre of the nebula

"A planetary nebula, often abbreviated as PN or plural PNe, is a kind of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from old red giant stars late in their lives. The word "nebula" is Latin for mist or cloud, and the term "planetary nebula" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed  They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.
A mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red-giant phase, the outer layers of the star are expelled by strong stellar winds. After most of the red giant's atmosphere is dissipated, the ultraviolet radiation of the hot luminous core, called a planetary nebula nucleus (PNN), ionizes the outer layers earlier ejected from the star. Absorbed ultraviolet light energises the shell of nebulous gas around the central star, causing it to appear as a brightly coloured planetary nebula.

The Dumbbell Nebula (also known as Apple Core Nebula, Messier 27, M 27, or NGC 6853) is a planetary nebula in the constellation Vulpecula, at a distance of about 1,360 light-years.
This object was the first planetary nebula to be discovered; by Charles Messier in 1764. At its brightness of visual magnitude 7.5 and its diameter of about 8 arcminutes, it is easily visible in binoculars." Credit: Wikipedia