Relics of Cygnus

Hidden away in the rich star-fields of Cygnus lies one of the galaxy’s oldest known planetary nebulae, the Methuselah Nebula, or MWP 1. This very faint, ghostly shell of gas is all that remains of a star nearing the end of its long cosmic life.

MWP 1 was first identified in 1992 by German astronomers C. Motch, K. Werner, and M. W. Pakull, whose initials give the nebula its name. Catalogued as RX J2117.1+3412, the central star of the nebula was discovered in a survey with the ROSAT satellite in the early 1990s. It is classified as a GW Virginis star, a pulsating white dwarf whose brightness varies due to non-radial gravity wave pulsations.

The nebula surrounding this star is unusual for its spectral signature. MWP 1 is mostly OIII (doubly ionized oxygen) emission, yet it lacks detectable diatomic nitrogen, this is uncommon trait among planetary nebulae. This chemical fingerprint hints at a highly evolved, possibly metal-poor progenitor star.

Sharing the same celestial field is a smaller, fainter planetary nebula named Alv 1 (PN G 79.8–10.2). It was discovered by Portuguese amateur astronomer Filipe Alves, who found it while imaging MWP 1.