Finally a break in the clouds and a chance at my first attempt at M97 and M108 with my WilliamOptics FLT91.

A word about Planetary Nebula'sA planetary nebula is a region of cosmic gas and dust formed from the cast-off outer layers of a dying star. Despite their name, planetary nebulae have nothing to do with planets.When stars with an intermediate mass (greater than 80% of the Sun’s mass, but less than eight times its mass) die, they expand to form red giants. The dying star will continue to expel gas, whilst simultaneously the remaining core of the star contracts and temporarily begins to radiate energy again. This energy causes the expelled gas to ionise, meaning that the atoms and molecules in the gas become charged and begin to emit light. The cast-off glowing gas is known as a planetary nebula. Therefore, planetary nebulae are classified as emission nebulae, and are entirely unrelated to planets. The misnomer came about because of a historical misclassification. 250 years ago, astronomers thought they were looking at gas planets when they observed the colourful spectacle of planetary nebulae through their less powerful telescopes. Planetary nebulae only last for about 20 000 years, making them a very short-lived part of the stellar life cycle.Throughout the years, Hubble has studied and imaged varying shapes and colours of these intricate planetary nebulae, the different colours arising from different, often newly created, chemical elements, showing that the final stages of the lives of stars are more complex than once thought. You can explore Hubble’s beautiful collection of planetary nebula images.Messier 97:The Owl Nebula, is a famous planetary nebula located in Ursa Major constellation. The nebula lies at a distance of 2,030 light years from Earth and has an apparent magnitude of 9.9. It has the designation NGC 3587 in the New General Catalogue.

Messier 97 occupies an area 3.4 by 3.3 arc minutes in apparent size, which corresponds to a spatial diameter of 1.82 light years. It was named the Owl Nebula because of its appearance in larger telescopes, which reveal two dark patches that look like the eyes of an owl. These were first sketched by William Parsons, 3rd Earl of Rosse in 1848.The Owl Nebula can be found about 2.5 degrees southeast of Merak, Beta Ursae Majoris. The star marks the southwest corner of the Big Dipper’s bowl and, together with Dubhe, Alpha Ursae Majoris, the star at the northwest corner, it points the way to Polaris. Going from Merak, M97 lies just over 2.5 degrees in the direction of Phecda (Phad), the other star at the bottom of the Dipper’s bowl.
The barred spiral galaxy M108, can be seen 50 arc minutes northwest of the Owl Nebula. The two objects appear in the same wide field view. The best time of year to observe M97 is during the spring, but observers north of latitude 35N can see the nebula throughout the year, as it never sets below the horizon in for them.Like most planetary nebulae, M97 appears brighter visually than photographically because it emits most of its light in one green spectral line. Its outer halo was not detected until 1991. The nebula formed when a dying Sun-like star ran out of hydrogen fuel, collapsed from a red giant to a white dwarf, and ejected its outer envelope. The expelled material is now heated by the radiation of the central white dwarf, producing the nebula’s glow. The nebula has been gradually expanding and will completely disperse into space over the next several thousand years, while the white dwarf will cool and fade away over the next several billion years.The estimated age of the Owl Nebula is about 8,000 years. The nebula is expanding at a velocity in the range from 27 to 39 km/s. It contains about 0.13 solar masses of material, including the elements hydrogen, helium, nitrogen, oxygen and sulphur. The matter within the nebula has a density of less than 100 particles per cubic centimetre.

The 16th magnitude central white dwarf has about 0.7 solar masses and is between 41 and 148 times brighter than the Sun. The star’s estimated temperature is about 123,000 K.When it collapsed, the central star expelled a large amount of matter in two opposing directions, which resulted in the nebula’s owl-like appearance. The two jets of matter are almost aligned with our line sight, but just slightly off. The dust in the jets blocks some of the light of the expanding nebula, giving it the appearance of two dark eyes. The jet pointing in our direction appears as the darker eye, while the one pointing away from us appears slightly fainter.The M97 nebula is arranged in three concentric shells. The outermost shell is about 20 to 30 percent larger than the inner shell, which is not circularly symmetric and forms a barrel-like structure that gives M97 its owl-like appearance when seen from Earth. The barrel-like structure is aligned at a 45-degree angle to our line of sight.

The Owl Nebula’s appearance isn’t unique. The Southern Owl Nebula (ESO 378-1), located in the constellation Hydra, bears a striking resemblance to it.Messier 97 is one of only four planetary nebulae listed in the Messier catalogue. The other three are the Dumbbell Nebula(M27) in Vulpecula, the Ring Nebula (M57) in Lyra, and the Little Dumbbell Nebula (M76) in Perseus constellation.The Owl Nebula was discovered by French astronomer Pierre Méchain on February 16, 1781. Méchain reported the discovery to his friend and colleague Charles Messier, who added the nebula to his catalogue.

Messier 108:Messier 108 (M108), nicknamed the Surfboard Galaxy, is a barred spiral galaxy located in the constellation Ursa Major. The galaxy lies at an approximate distance of 45.9 million light years from Earth and has an apparent magnitude of 10.7. It has the designation NGC 3556 in the New General Catalogue.Messier 108 occupies an area of 8.7 by 2.2 arc minutes of apparent sky, corresponding to a spatial diameter of 110,000 light years. The galaxy is inclined 75 degrees to our line of sight. Even though it appears almost edge-on, M108 is a popular target among amateur astronomers and astrophotographers because details of its structure can be seen even in amateur telescopes. 3-inch telescopes will only reveal an elongated streak of light with a brighter core, while 8-inch instruments will hint at the galaxy’s dusty regions and bright and faint patches.The galaxy is easy to find as it lies only 1.5 degrees southeast of the magnitude 2.37 star Merak, Beta Ursae Majoris, one of the Pointer Stars in the Big Dipper. M108 appears in the same wide field of view with the Owl Nebula (M97), which is located only 48 arc minutes southeast of the galaxy. The best time of year to observe M108 is during the spring. The galaxy is circumpolar north of latitude 35N and can be seen throughout the year.Messier 108 has the morphological classification SBbc, which means that it is a barred spiral galaxy with somewhat loosely wound spiral arms. The galaxy does not have a pronounced core or bulge, but appears very mottled and dusty, with few H II regions and clusters of young stars. The dust structures are prominent in the galaxy’s disk and very thick in front of its bulge. The central region of M108 is bright and irregular, with a large central bar.The estimated mass of M108 is about 125 billion solar masses. The galaxy contains about 400 billion stars and an estimated population of 290 globular clusters. M108 is receding from us at 699 km/s.Messier 108 also contains H1 supershells, shells of expanding gas driven either by bursts of star formation and the resulting supernova explosions, or by infall of gas from outside the galaxy, or possibly by radio jets. The H1 supershells in M108 extend for several kiloparsecs.Messier 108 contains 83 X-ray sources, discovered by the Chandra X-ray Observatory. One of these sources was found at the nucleus and its spectrum indicates an active galactic nucleus (AGN). However, observations with the Spitzer Space Telescope have not confirmed this. The brightest X-ray source in M108 is suspected to be an intermediate-mass black hole that is accreting matter. Diffuse soft X-ray radiation was discovered within 10 kiloparsecs of the optical galaxy.The supermassive black hole at the galaxy’s core has an estimated mass of 24 million solar masses, or six to eight times the mass of the supermassive black hole at the centre of the Milky Way.Messier 108 is one of the brightest, largest members of the Ursa Major Cluster, a cluster of galaxies located in the Virgo Supercluster. M108 is an isolated member of the group.A supernova, designated as SN 1969B, was observed in M108 at magnitude 13.9 on January 23, 1969. It was classified as a Type II supernova.Messier 108 was discovered by the French astronomer Pierre Méchain on February 19, 1781, only three days after he had found the Owl Nebula (M97). Charles Messier observed both M108 and M109 on March 24, 1781, when he determined the position for M97. However, Messier did not measure the positions of M108 and M109 at the time and only added them to his hand-written list of objects.