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Organic Molecules in the Magellanics

If for some reason I had to come up with a different name for Centauri Dreams, I think it might just be Magellanic Dreams. I say this because, like the Alpha Centauri stars themselves, the Magellanics have been something of an obsession since my childhood. Dwarf galaxies orbiting the Milky Way, the Large and Small Magellanic Clouds took my imagination outside our galaxy to a place where it could be viewed in all its splendor (or maybe not: See The Milky Way from Outside for why galaxy viewing can be problematic).

The Large Magellanic Cloud is 160,000 light years away (contrast this with M-31’s 2.5 million light years), while the SMC is about 200,000 light years out. Science fiction brought us Olaf Stapledon’s telepathic aliens living in the LMC — these guys were made to order for the emerging field of Dysonian SETI in that they did engineering on a planetary scale (see Star Maker for more). And remember where the spacecraft in Arthur C. Clarke’s Rendezvous with Rama was heading at the end? It appeared to have used its solar assist to set course for the LMC.

Image: The Large Magellanic Cloud and Supernova 1987A taken by the Kuiper Airborne Observatory (NASA 714) during its New Zealand deployment in 1987. Credit: NASA.

There are too many science fiction references to the Large and Small Magellanics to get into today, from Heinlein’s Have Space Suit Will Travel to Iain Banks’ The Player of Games. I’m now trying to curb my SF enthusiasm (but do read Silverberg’s Collision Course some time to get the backward view of the Milky Way from the LMC). Because what triggered all these thoughts is new work out of the National Radio Astronomy Observatory on the subject of unusual findings in the Large Magellanic Cloud.

Here we’re dealing with data from the Atacama Large Millimeter/submillimeter Array (ALMA). Astronomer Marta Sewiło (NASA GSFC) and colleagues have found clear evidence of complex organic molecules in the Large Magellanic Cloud, including methanol, dimethyl ether, and methyl formate. The finding raises the eyebrows just a bit because the LMC is nowhere near as rich in heavy elements like carbon, nitrogen and oxygen as our Milky Way — in astronomical terms, these dwarf galaxies exhibit low metallicity. While methanol has been studied in the LMC before, the dimethyl ether and methyl formate are new findings.

Image: Astronomers using ALMA have uncovered chemical “fingerprints” of methanol, dimethyl ether, and methyl formate in the Large Magellanic Cloud. The latter two molecules are the largest organic molecules ever conclusively detected outside the Milky Way. The far-infrared image on the left shows the full galaxy. The zoom-in image shows the star-forming region observed by ALMA. It is a combination of mid-infrared data from Spitzer and visible (H-alpha) data from the Blanco 4-meter telescope. Credit: NRAO/AUI/NSF; ALMA (ESO/NAOJ/NRAO); Herschel/ESA; NASA/JPL-Caltech; NOAO.

Focusing on two star-forming ‘embryos’ in the LMC (also known as ‘hot cores’), the astronomers think they’re gaining insights into the formation of complex organic molecules in the early universe. That’s because dwarf galaxies with relatively low masses produce a slower rate of star formation, so the LMC may well be chemically similar to distant, younger galaxies. Seeding a galaxy with heavy elements takes generations of star formation and evolution. Says Sewiło:

“Even though the Large Magellanic Cloud is one of our nearest galactic companions, we expect it should share some uncanny chemical similarity with distant, young galaxies from the early universe… Young, primordial galaxies simply didn’t have enough time to become so chemically enriched. Dwarf galaxies like the LMC probably retained this same youthful makeup because of their relatively low masses, which severely throttles back the pace of star formation.”

The LMC’s N113 Star Formation Region is massive and rich in gas, with a large number of protostars that throw a bright infrared signature. Several of these young stellar objects have produced the spectral evidence for dimethyl ether and methyl formate. The latter two have never been detected at such a distance from Earth, while methanol, a relatively simple compound, is significant because it is essential for the formation of the more complex organic molecules.

Tying these findings to implications for the early universe, the researchers note that the presence of complex organic molecules — molecules containing six or more atoms including carbon — around protostars indicates they would likely be incorporated in emerging protoplanetary disks. Indeed, such molecules may well have been delivered to the young Earth by comets and meteorites. And if chemically primitive regions like the LMC can produce them, then we have the possibility that life could have taken hold early in the history of the cosmos, as these are the building blocks of molecules that are essential to its emergence.

The paper is Sewiło et al., “The Detection of Hot Cores and Complex Organic Molecules in the Large Magellanic Cloud,” Astrophysical Journal Letters Vol. 853, No. 2 (30 January 2018). Abstract.


Comments on this entry are closed.

  • Mike January 31, 2018, 15:31

    Hi Paul. In your travels did you ever spend time far enough south to get a good look at the southern sky? Allowing you to observe the LMC , SMC and the Southern Cross and Centaurus? If so, good for you.

    I find it very suggestive that life apparently arose on Earth as soon as it was possible after the Late Heavy Bombardment according to the fossilized stromatolite evidence. On an early Earth that was harsh and inhospitable to life as we know it. Not a place that was tailor-made and pre-shaped for life.

    The accumulated findings from the various planet hunting projects over the last two decades indicate that planets are ubiquitous. So planets are everywhere and going by our one available sample life arises as soon as it can. Yes, very suggestive indeed. More data needed.

    • Paul Gilster January 31, 2018, 22:49

      Alas no, though a trip to see the southern sky has always been a goal of mine, and one I intend to manage one of these days!

  • David January 31, 2018, 22:50

    LMC is to intergalactic travel what Proxima Centauiri is to interstellar…..Breakthrough Starshot will get there in 800000 years. Not worried about the return signal and while I am optimistic on aging research…. i dont think any of usvwill be around in 960000 years……..deep time.

    • Mark Zambelli February 1, 2018, 12:25

      Speak for yourself ;D (although I am still waiting on my “Graham’s Number Life Extension Kit” to arrive, haha)

      I’m glad Iain M Banks gets a ‘shout-out’ (and IIRC he sets up the notion of the LMC as being a Culture-destination in his first book ‘Consider Phlebas’, right in the closing pages.)… he’ll be sorely missed for a longtime yet, imho.

      • Paul Gilster February 1, 2018, 17:13

        Yes, and I really enjoyed The Player of Games, where the Magellanics are so prominent.

  • Jamrs Franklin February 1, 2018, 2:44

    Very interesting research and most certainly warranting of further efforts, but we need to be mindful when discussing life and chemicals that play an important role as precursors to a poorly understood process not to conflate this research with the search for extrasolar life.

  • DJ Kaplan February 7, 2018, 13:34

    I’m normally pretty skeptical about “life” (rather than “mere” nucleotides), but this study seems interesting.
    The article doesn’t mention where their measurements came from, or how they knew the viruses and bacteria were falling “down” from apparently outer space, but it’s still interesting.