One of the last images I was able to take before the long pause due to bad weather in winter 2022-2023. The image was taken in three windows of decent sky on 25 October, 2 and 5 November 2022.

NGC 1514 - PK165-15.1

NGC 1514 is a planetary nebula in the zodiac constellation of Taurus. Distance to the nebula is 466 pc (1500 ly), less than previously believed.

It was discovered by William Herschel on November 13, 1790, describing it as "a most singular phenomenon" and forcing him to rethink his ideas on the construction of the heavens. Up until this point Herschel was convinced that all nebulae consisted of masses of stars too remote to resolve, but now here was a single star "surrounded with a faintly luminous atmosphere." He concluded: "Our judgement I may venture to say, will be, that the nebulosity about the star is not of a starry nature."

This is a double-shell nebula that is described as, "a bright roundish amorphous PN" with a radius of around 65″ and a faint halo that has a radius of 90″. It consists of an outer shell, an inner shell, and bright blobs. The inner shell appears to be distorted, but was likely originally spherical. An alternative description is of "lumpy nebula composed of numerous small bubbles" with a somewhat filamentary structure in the outer shell. Infrared observations show a huge region of dust surrounds the planetary nebula, spanning 8.5 ly (2.6 pc). There is also a pair of rings forming what appears to be a hourglass-like structure, similar to those found in MyCn 18 (aka Engraved Hourglass Nebula, in southern Musca constellation), but these are extremely faint and only visible in the mid-infrared, The combined mass of the gas and dust is estimated at 2.2±1.4 M☉. The ionized gas is moderately excited, and the electron temperature is estimated to be 15,000 K.

The nebula originated from a binary star system with the designation HD 281679 from the Henry Draper Catalogue. The bright, visible component is a giant star on the horizontal branch with a stellar classification of A0III, while the nebula-generating companion is now a hot, sub-luminous O-type star. The two were originally thought to have an orbital period on the order of 10 days, but observations of the system over years showed that their orbit is actually one of the longest known for any planetary nebula, with a period of about 9 years.
(Excerpted and edited by Wikipedia)


Picture 1: The view on the right shows the object in infrared light, as seen by NASA’s Wide-field Infrared Survey Explorer, or WISE. The object is actually a pair of stars — one star is a giant somewhat heavier and hotter than our sun, and the other was an even larger star that has now contracted into a dense body called a white dwarf. As the giant star ages, it sheds some its outer layers of material to form a large bubble around the two stars. Jets of material from the white dwarf are thought to have smashed into this bubble wall. The areas where the jets hit the cavity walls appear as orange rings in the WISE image. This is because dust in the rings is being heated and glows with infrared light that WISE detects. The green cloud seen in the WISE view is an inner shell of previously shed material. In the visible image, this shell is seen in bright, light blues. An outer shell can also be seen in the visible image in more translucent shades of blue. This outer shell is too faint to be seen by WISE. Image: NASA/JPL-Caltech/UCLA/Digitized Sky Survey/STScI, Description excerpted by constellation-guide.com