ABSTRACT IT has long been suspected1 that OH–IR sources, highly evolved red giant stars that have built up massive, cool gaseous envelopes through heavy mass loss, are precursors to

planetary nebulae. The two kinds of object share a similar galactic distribution, and their circumstellar envelopes have comparable masses and expansion velocities2,3. Recently, several

hybrid objects have been found with the far infrared and OH maser emission characteristic of the OH–IR sources, but also with radio continuum emission from a central H II region4–6. There is

strong circumstantial evidence that these objects, of which the prototype is Vy2–2 (refs 4,7), seem to be in a transitional state, but their precise evolutionary status remains unclear.

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MESSY DEATH OF A MULTIPLE STAR SYSTEM AND THE RESULTING PLANETARY NEBULA AS OBSERVED BY JWST Article 08 December 2022 THE METAL-POOR ATMOSPHERE OF A POTENTIAL SUB-NEPTUNE PROGENITOR Article

Open access 09 May 2024 UNCOVERING THE INTEGRAL SPECTRAL CHARACTERISTICS OF THE PLANETARY NEBULA IC 4642 Article Open access 13 May 2025 REFERENCES * Elitzur, M., Goldreich, P. &

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Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire, SK119DL, UK M. C. Shepherd & R. J. Cohen * Hartebeesthoek Radio Astronomy Observatory, PO Box 443, Krugersdorp, 1740,

South Africa M. J. Gaylard & M. E. West Authors * M. C. Shepherd View author publications You can also search for this author inPubMed Google Scholar * R. J. Cohen View author

publications You can also search for this author inPubMed Google Scholar * M. J. Gaylard View author publications You can also search for this author inPubMed Google Scholar * M. E. West

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R., Gaylard, M. _et al._ OH–IR sources as precursors to protoplanetary nebulae. _Nature_ 344, 522–524 (1990). https://doi.org/10.1038/344522a0 Download citation * Received: 09 November 1989

* Accepted: 16 February 1990 * Issue Date: 05 April 1990 * DOI: https://doi.org/10.1038/344522a0 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this

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