Surprise: Freon detected around a distant star, comet

From the “Nature just wanted Freon for herself” department and the European Southern Observatory: ALMA and Rosetta detect Freon-40 in space
Dashing hopes that molecule may be marker of life

Organohalogen methyl chloride (Freon-40) discovered by ALMA around the infant stars in IRAS 16293-2422. These same organic compounds were discovered in the thin atmosphere surrounding Comet 67P/C-G by the ROSINA instrument on ESA’s Rosetta space probe.

Using data captured by ALMA in Chile and from the ROSINA instrument on ESA’s Rosetta mission , a team of astronomers has found faint traces of the chemical compound [Freon-40] – (CH3Cl), also known as methyl chloride and chloromethane, around both the infant star system IRAS 16293-2422 [1], about 400 light-years away, and the famous comet 67P/Churyumov-Gerasimenko (67P/C-G) in our own Solar System. The new ALMA observation is the first detection ever of a stable organohalogen in interstellar space [2].

Approximate location of Comet 67P/Churyumov–Gerasimenko when the ROSINA instrument on ESA’s Rosetta space probe discovered traces of Freon-40 (methyl chloride), the same molecule detected by ALMA around the IRAS 16293-2422 star-forming region.

Organohalogens consist of halogens, such as chlorine and fluorine, bonded with carbon and sometimes other elements. On Earth, these compounds are created by some biological processes — in organisms ranging from humans to fungi — as well as by industrial processes such as the production of dyes and medical drugs [3].

This new discovery of one of these compounds, Freon-40, in places that must predate the origin of life, can be seen as a disappointment, as earlier research had suggested that these molecules could indicate the presence of life.

“Finding the organohalogen Freon-40 near these young, Sun-like stars was surprising,” said Edith Fayolle, a researcher with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts in the USA, and lead author of the new paper. “We simply didn’t predict its formation and were surprised to find it in such significant concentrations. It’s clear now that these molecules form readily in stellar nurseries, providing insights into the chemical evolution of planetary systems, including our own.”

Exoplanet research has gone beyond the point of finding planets — more than 3000 exoplanets are now known — to looking for chemical markers that might indicate the potential presence of life. A vital step is determining which molecules could indicate life, but establishing reliable markers remains a tricky process.

“ALMA’s discovery of organohalogens in the interstellar medium also tells us something about the starting conditions for organic chemistry on planets. Such chemistry is an important step toward the origins of life,” adds Karin Öberg, a co-author on the study. “Based on our discovery, organohalogens are likely to be a constituent of the so-called ‘primordial soup’, both on the young Earth and on nascent rocky exoplanets.”

This suggests that astronomers may have had things around the wrong way; rather than indicating the presence of existing life, organohalogens may be an important element in the little-understood chemistry involved in the origin of life.

Co-author Jes Jørgensen from the Niels Bohr Institute at University of Copenhagen adds:

“This result shows the power of ALMA to detect molecules of astrobiological interest toward young stars on scales where planets may be forming. Using ALMA we have previously found precursors to sugars and amino acids around different stars. The additional discovery of Freon-40 around Comet 67P/C-G strengthens the links between the pre-biological chemistry of distant protostars and our own Solar System.”

The astronomers also compared the relative amounts of Freon-40 that contain different isotopes of chlorine in the infant star system and the comet — and found similar abundances. This supports the idea that a young planetary system can inherit the chemical composition of its parent star-forming cloud and opens up the possibility that organohalogens could arrive on planets in young systems during planet formation or via comet impacts.

“Our results shows that we still have more to learn about the formation of organohalogens,” concludes Fayolle. “Additional searches for organohalogens around other protostars and comets need to be undertaken to help find the answer.”



[1] This protostar is a binary star system surrounded by a molecular cloud in the Rho Ophiuchi star-forming region, which makes it an excellent target for ALMA’s millimetre/submillimetre view.

[2] The data used were from the ALMA Protostellar Interferometric Line Survey (PILS). – The aim of this survey is to chart the chemical complexity of IRAS 16293-2422 by imaging the full wavelength range covered by ALMA in the 0.8-millimetre atmospheric window on very small scales, equivalent to the size of the Solar System.

The species CF+, which could be considered as an organohalogen, had already been detected, but is not stable.

[3] Freons were widely used as a refrigerants (hence the name) but are now banned as they have a destructive effect on the Earth’s protective ozone layer.

More information

This research was presented in a paper “Protostellar and Cometary Detections of Organohalogens” by E. Fayolle et al., to appear in Nature Astronomy on 2 October 2017.


52 thoughts on “Surprise: Freon detected around a distant star, comet

  1. For some reason this reminds me of Rachel Carson’s rant on how unnatural (and dangerous) chlorocarbons were in “Silent Spring”.

      • I saw your comment after posting mine below. I followed your link and it seems that the place where they found ozone was in the high-velocity dispersion region of the Orion nebula, a star nursery.

    • My though exactly
      But you should had put /sarc tag, or you can bet some will think it for real.

      • A few weeks back, I put up a post postulating about anthropological CO2’s ability to change the sun, and a couple of people jumped down my throat.

    • Lucky this information comes to us from 400,000 years ago otherwise they would be jumped on by the IPCC for releasing banned chemicals into the universe.

    • Contamination of interstellar space is against the Federation’s prime directive of non-interference.
      Sarc factor seven, ensign Crusher.

  2. Staggering news: Freon-40 has exited the Earth’s gravitational pull and has begun to nibble away at a star some 400 light years away, impacting a comet in the process. Freon-40 must therefore travel much faster than the speed of light. /sarc.

  3. Any chance dry cleaning vapour (carbon tetrachloride) might be a good alternative to look for? Presumably alien life would like to keep its clothes clean too and some of the life forms I’ve seen going into dry cleaning shops….

  4. So this means I can keep my environment-contaminating refrigerator and not have to get that Amish carpenter to build me a Hoosier icebox, after all?

    That’s good. Not giving up my 7.0 CuFt freezer, either. It’s full of chicken, potatoes and mixed veggies, and maybe some ice cream… or not. :)

  5. It’s not a complex organic molecule. I don’t think anyone should be excited by its occurrence.

    • There have been some excellent posts on this blog with evidence that Freon does not affect the Ozone Hole, or if it did, to an measurably tiny degree. There were other natural events that did cause the holes to wax and wane in size.

      • Kaliforniakook, Ferdinand

        Ozone is not the only substance being formed TOA. We are being protected by our atmosphere from the most energetic particles from the sun as they initiate the formation of ozone, peroxides and N-oxides from their basic compounds, i.e. oxygen, water and nitrogen.
        In its turn, these substances screen out some of the most harmful UV as well.
        As far as the ozone ‘hole’ is concerned: they never measured how much peroxides were in the hole? Now take a peek at the spectrum of H2O2 and compare it which the one of ozone/? Do you the great similarity?
        So, HxOx is doing the same thing as O3….
        It is likely to assume that above the oceans there are much more OH radicals.
        Hence, peroxides are likely formed here preferentially to ozone.
        So, unless somebody shows us some figures [on peroxides], I very much doubt that there ever was an ozone hole.
        Unless someone has some proof to convince me otherwise?

      • Henryp,

        Most ozone is formed at the equator by UV, and that is slowly transported polewards by the ITCZ which pushes air from the ground to very high heights. While flowing polewards, some more is formed and some is depleted by natural and human chemicals (and again by UV). Ozone intensity is highest near the equator, but, despite that, UV intensity at ground level is much higher there too, due to the angle of incoming radiation (a factor 5 if I remember well). As far as I remember, there is little overall change in that process and little increase in destruction.

        During the Antarctic winter, there is a strong vortex around that continent and at extreme low temperatures ice crystal clouds are formed where a specific (NOx and Cl containing) chemical compound condenses. When in spring the sun starts shining, that chemical compound is destroyed and gives a lot of elementary chlorine at once, while the vortex prevents the supply of fresh ozone from the tropics. That makes a dip in ozone concentration in a part of the stratosphere where there are hardly any animals and humans beneath. After a few weeks the vortex disappears and the ozone levels go back to normal. Thus a lot of fuss for a small problem – if a problem at all…

      • Ferdinand
        The measurements you referred to, are of the radicals OH and OH2. They are in fact the building blocks of the peroxides that I referred to.
        So in your opinion, which reaction is more probable:

        3 O2 + x radiation [of y wavelength] => 2 O3


        2 OH + x radiation [of y wavelength] => H2O2

        given that at a certain height TOA both O2 and OH would be present at the same quantity.

    • A little prudence here…

      While it is true that there probably was a natural ozone hole every spring in Antarctica, one can’t exclude the influence of human emissions of CFC’s as chlorine donor besides the natural chlorine containing chemicals like CH3Cl.

      What is true is that the basic chemistry as thought before can’t be true as one of the steps is much too slow. But the overall destruction of ozone by elementary chlorine (and other active chemicals) on the surface of ice crystals at temperatures below -80ºC with UV-light is proven.

  6. OK, government funded scientists seem to have a hard time taking, keeping and managing basic temperature measurements here on Earth. So we are to believe that they can measure the occurrence of a compound four hundred light years away. Interestingly I have had several discussion with folks about planets around distant stars. Most believe we now have the telescopes where we can actually see such planets around other stars, not that the astronomers are basically using proxy data to determine whether such planets exist or not. The same folks also believed we will soon be traveling, with in their life times, to such distant stars and planets. They believe it should be a priority since we are destroying earth with carbon dioxide emissions.

  7. It’s not clear how the presence of methyl chloride can be considered a precursor to life. Life on earth requires amino acids (compounds of carbon, nitrogen, oxygen and hydrogen, with some containing sulfur) and DNA (compounds of carbon, oxygen, hydrogen, and phosphorus), but the chlorine atom only plays a minor role in the chemistry of life.

    Most of the naturally-occuring chlorine on earth is bound in inorganic ionic salts, either as solids or dissolved in sea water (as sodium chloride). It’s true that the stomachs of most mammals (including humans) contain hydrochloric acid (HCl), but it is formed from sodium chloride in the diet, rather than from methyl chloride, which is a very rare gas in earth’s atmosphere.

    It is interesting that methyl chloride was found on a comet, far from any human-made refrigerators.

  8. This simply means that detection methods keep improving. Pretty soon the EPA will use them to ban anything containing more than 0.0000001% of Freon or Arsenic.

  9. There are numerous carbon-based molecules produced by stars when they die. For a list of some interesting and unusual ones, see “Up the Starry Chimney”, a New Scientist article. Life on stable planets around stable stars is inevitable.

    • Not to be forgotten the Phoenix area: thanks to freon the base of many military projects in the early 1940’s and the start of Honeywell in both the A/C world and process (military and chemical). Also the origin of the explosion of suburbs around Phoenix for the end-of-life awaiting pensioners…

  10. So someone 400 light years away has fridges!
    We are not alone!
    Lets put Oliver Macron, Leonardo DiCaprio, Al Gore and a bunch of UN officials on a space ship to get them to sign up to the Paris accord.

  11. All this nonsense has much more to do with the economics of selling R-134a at $1.50/oz instead of R-12 at $0.68/lb than anything to do with science and saving the planet…..

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