Astronomers have identified a faint planetary nebula during a spectroscopic examination of stars in NGC 1866, a vast young globular cluster within the Milky Way satellite galaxy, known as the Large Magellanic Cloud. This nebula, designated Ka LMC 1, is situated near the core of NGC 1866.
This image shows NGC 1866 overlaid with a false-color representation from the MUSE data cube, highlighting the ionized shell of planetary nebula Ka LMC 1 as a red ring. The grayscale inset details the sizes of the ionization shells of singly ionized nitrogen. [N II] and doubly ionized oxygen [O III]. A magnified Hubble image reveals a pale blue star at the center, likely the hot central star of Ka LMC 1. Image credit: AIP / MM Roth / NASA / ESA / Hubble.
NGC 1866 is located at the edge of the Large Magellanic Cloud, approximately 160,000 light-years from Earth.
This cluster, also referred to as ESO 85-52 and LW 163, was discovered by Scottish astronomer James Dunlop on August 3, 1826.
Surprisingly, NGC 1866 is a young globular cluster positioned close enough for individual star studies.
In a recent spectroscopic investigation of NGC 1866, astronomers analyzed spectra captured by the MUSE Integral Field Spectrometer on ESO’s Very Large Telescope.
They made an unexpected and intriguing discovery: the ionized shell of a planetary nebula.
A subsequent study utilized images from the NASA/ESA Hubble Space Telescope to explore the nature of the object, which has been named Ka LMC 1.
“Planetary nebulae signify a late phase in a star’s evolution, during which the star consumes hydrogen for nucleosynthesis, expands as a red giant in a shell-burning phase, and eventually sheds most of its mass into a large, expanding shell. The remaining core then contracts and heats up, eventually cooling to become a white dwarf,” explained lead author Dr. Howard Bond, an astronomer at Pennsylvania State University and the Space Telescope Science Institute, along with his colleagues.
“Once the core surpasses 35,000 degrees, the shell ionizes and becomes visible through emission lines at specific wavelengths.”
The research team noted that Hubble images depict the hot central star of the Ka LMC 1 nebula.
“Ka LMC 1 is a genuine enigma. A young star cluster aged 200 million years implies that its progenitor star must be significantly massive,” noted astronomer Professor Martin Roth from the Potsdam Leibniz Institute for Astrophysics, the Institute for Physics and Astronomy at the University of Potsdam, and the German Center for Astrophysics.
“However, such a star would quickly evolve towards a cooling white dwarf stage.”
“Reconciling the age of the planetary nebula’s expanding shell with the theoretical evolutionary trajectory of its central star has been challenging.”
“This object undoubtedly demands further detailed observations to clarify its characteristics.”
“It presents a rare opportunity to observe star evolution over a timeframe that usually spans millions, if not billions, of years.”
“Yet, the evolution of massive central stars occurs in merely a few thousand years, making it possible to align with the timeline of the nebula’s expansion.”
According to a study published on November 7, 2025, in Publications of the Astronomical Society of the Pacific.
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Howard E. Bond et al. 2025. A faint planetary nebula was accidentally discovered in the massive young LMC star cluster NGC 1866. pasp 137, 114202; doi: 10.1088/1538-3873/ae1664
Source: www.sci.news
