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Planetary nebula – the glowing gaseous shells thrown off by stars during the latter stages of their evolution – were thought to only form around stars the size of our Sun or smaller. Although astronomers had predicted these shells should form around “heavier” stars, none had ever been detected. Until now. An international team of scientists have discovered a new class of object which they call “Super Planetary Nebulae,” found around stars up to 8 times the mass of the Sun.
“This came as a shock to us,” said Miroslav Filipovic from the University of Western Sydney “as no one expected to detect these object at radio wavelengths and with the present generation of radio telescopes. We have been holding up our findings for some 3 years until we were 100% sure that they are indeed Planetary Nebulae”.
The team surveyed the Magellanic Clouds, the two companion galaxies to the Milky Way, with radio telescopes of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Australia Telescope National Facility. They noticed that 15 radio objects in the Clouds match with well known planetary nebulae observed by optical telescopes.
The new class of objects are unusually strong radio sources and are associated with larger original stars (progenitors), up to 8 times the mass of the Sun. The nebular material around each star may have as much as 2.6 times the mass of the Sun.
Filipovic’s team argues that the detections of these new objects may help to solve the so called “missing mass problem” – the absence of planetary nebulae around central stars that were originally 1 to 8 times the mass of the Sun. Up to now most known planetary nebulae have central stars and surrounding nebulae with respectively only about 0.6 and 0.3 times the mass of the Sun but none have been detected around more massive stars.
Some of the 15 newly discovered planetary nebulae in the Magellanic Clouds are 3 times more luminous than any of their Milky Way cousins. But to see them in greater detail astronomers will need the power of a coming radio telescope – the Square Kilometre Array planned for the deserts of Western Australia.
The scientist’s paper appears in the journal Monthly Notices of the Royal Astronomical Society.
Lead image caption: An optical image from the 0.6-m University of Michigan/CTIO Curtis Schmidt telescope of the brightest Radio Planetary Nebula in the Small Magellanic Cloud, JD 04. The inset box shows a portion of this image overlaid with radio contours from the Australia Telescope Compact Array. The planetary nebula is a glowing record of the final death throes of the star. (Optical images are courtesy of the Magellanic Cloud Emission Line Survey (MCELS) team).
Source: RAS
Err… Nancy, at paragraph 6, line 2:
That should be than, not “then”. 😉
This seems to be a quite unexpected discovery. Kudos to the team of scientists who thoroughly re-checked their work before publishing this result.
As to whether this discovery will solve the missing mass problem remains to be seen, though. I find it more reasonable to think that this discovery may help to solve the missing mass problem. My first thought wrt to this statement was: just how common are these ‘heavy PNe’ ? Just how rare (or common) are these objects and in what numbers do they occur? There would have to be a large number of them (including massive ‘dark’ remnants of former PNe) to completely account for the missing mass.
I wonder why there are no PN around massive stars. Since they shed their material like a dying low mass star, but just over their whole lifetime, there should be nebula-like structures around massives stars while they are alive. We don’t just name it that way, do we?
And there should be no nebula after the death of the massive star, since the supernova explosion should throw away all the material.
Or is there probably something different at work. Something in which shedded “massive star”-material differs from “planetary nebula”-material?
(It seems I don’t know enough of those things 😉 )
Excuse me guys and grrrls [boys and girls for the conscientious], but I find the discussion here thoroughly confusing.
These 2 (3) conflicting sentences is of the type that will send me into conniptions. I wonder what an Aspberger type would do with them? For myself, I have learned that it is easy to drop a word or two that would make the context clear and content unambiguous.
Maybe that should be “… were once thought to only form …” and “… astronomers more recently had predicted these shells …”.
But then again it doesn’t explain the comments where again it is assumed “… no PN around massive stars”, while the article seems to say otherwise. Ouch, my poor head! Sometimes astronomy makes one acquainted with a void…
DrFlimmer:
Neither does science in general, which is why it never stops research — unlike those EU/PC nutjobs who think that they ‘know’ everything!
@ Nancy,
The name of the scientist, Miloslav Filipović, in the above article, is of Serbo-Croatian origin and is spelt with a “ć” at the end; the HTML code for that letter with the acute accent diacritical is: &_#_263_; (omit the underscores). If it works for my comment, it should also work for you in the above article. 🙂
Maybe it’s true what they say:
“If you look long enough into astronomy, the void begins to look back through you.”
Err… that should be Miroslav, not “Miloslav”!
I think that I’m beginning to turn Chinese!
Details of these objects and their detection was recently posted as “Radio Planetary Nebulae in the Magellanic Clouds” here at the arXiv site: http://arxiv.org/PS_cache/arxiv/pdf/0906/0906.4588v1.pdf . Still, the numbers detected so far would only be a small fraction of the ‘missing mass’.
Jon:
I have a feeling that you may have misunderstood what they mean when they refer to the ‘missing mass’ problem in the context of planetary nebulae and such (Or i’m misunderstanding what you’re saying).
You realize that the ‘missing mass’ problem that the article refers to isn’t the same missing mass problem that gave rise to the discovery of dark matter right?
The missing mass problem being refered to in this article (as near as I have been able to tell) has to do with the fact that there a range of asymptotic giant branch stars that have been predicted to have planetary nebulae, but these have not been observed. The mass (of the planetary nebula) is missing because it’s predicted to be there by theory, however, up until now, has not been observed.
It’s completely unrelated to the missing mass problem of dark matter.
Trippy:
My Bad. Thanks for the clarification wrt the missing mass problem of planetary nebula and the cosmological ‘missing mass’ . I must have been reading too many dark matter papers lately 🙂
On a related note, I was curious if radio detection of Intra Cluster Planetary Nebulae (ICPNe) in the nearest galaxy clusters (Virgo, Coma) might be possible with new radio telescope facilities coming on line (like the SKA). Unfortunately, the authors of the paper point out just how difficult these observations of extragalactic PNe are. I noted that the authors mentioned two known radio PNe that have been detected in the Sagittarius Dwarf Galaxy, but when scaled to the distance of the Magellanic Clouds they would have been undetectable using their current techniques.