Flatulence in Space (III)

It’s sad to beg, but sadder is to beg over and over again, until exhausting our audience… It’s my case, I admit. It’s my fault. In my quest to increase the number of followers of the ASTROMOL’s Facebook account (wink-wink), I embarked on a smelly adventure in which I promised articles about stinky gases if I overcame every challenge. The first,  “Flatulence in Space (I)”,was published in August 2015. January 2016 saw the birth (or, rather, smelled the birth) of “Flatulence in Space (II)” and, since there are no two without three, we tried again. The last one was hard, but we’ve made it. And since I do what I promise, here’s the third (and who knows if the last one, snif) deliver of “Space Flatulences”. Don’t cry for me 😉


“Nature never ceases to amaze us.” As if it were the script of a documentary, I see myself pronouncing this phrase as I choose the title of this report. I know it’s a little scatological, but it’s totally true: let’s talk about some of the gases that are in our flatulence. Watch out, in our flatulence there’s not just gas, there are more things, but we’re not going to talk about those. The compounds that give farts that smell (not all smell the same, it will all depend on what we have ingested) are well known. And some of them are also in space. Now you’ll understand why I, who usually talk about Astrophysics and Astrochemistry, get into these issues.

Hydrogen sulfide and carbonyl sulfide are the two pestilent compounds we have already talked about in this series. But today we do not bring sulfide, today we bring methyl mercaptan or methanethiol (CH3SH), a second cousin of methanol (CH3OH), which replaces sulfur (S) with oxygen (O). This mercaptan, from the thiol family, is a colorless gas that smells of rotten cabbage (although, in truth, I’ve never smelled a rotten cabbage, anyone with experience? Comments, please).

It appears to be in numerous plant and animal tissues and occurs in some processes of bacterial breakdown of proteins from methionine (as Wikipedia faithfully tells us), that is, a zombie would stink of CH3SH. It’s in the poop and farts (and in the stinky breaths) but, pay attention, it’s also in our brains (I see the joke coming) and in the blood.

There are also some cheeses that contain it and smell like this, to methyl mercaptan (you have an example in the Beaufort’s cheese) because of the action of some unleashed microorganism. Swamps emanate this smelly compound, but exposure would only be dangerous if we talk about industrial issues (and yet the danger of methyl mercaptan is not demonstrated). It is used as a precursor to pesticides, in the manufacture of plastics and feed, to break down wood in paper factories and is added to jet aircraft fuels. 

Methanethiol is one of the gases added to the butane (remember that butane smells nothing) so that we get the olfactory alarms in case of leakage. (That reminds me of an olfactory fire alarm designed for deaf people who let out a wasabi spray. This research won an Ig Nobel Prize in 2011).

What about space?

Methyl mercaptan was detected in 1979 by Linke and collaborators in Sagittarius B2, a molecular cloud of the galactic center known to be one of the most productive massive star formation areas in the galaxy. So, we could already say that it had been detected in the interstellar medium.

Subsequent studies also detected the presence of methyl mercaptan towards the hot core of G327.3-0.6, a region of massive stars formation (this was the first time that methanethiol was found outside the galactic center).

It was also detected in the cold molecular cloud B1 (this cloud is located in the so-called First Hydrostatic Core stage, formed when the collapse phase at the star’s birth stage is stopped. We had already spoken before about this detection).

And, very recently, methyl mercaptan has been found in the protostar IRAS 16293-2422. Its finding suggests that there may be entire families of Sulphur-carrying molecules that have not yet been detected in protostars and would form from CH3SH.

It has been searched in other environments but, so far, has not yet been detected. Although there are proposals to use it as a biomarker when researching the surface of Mars. As a result of a biological process (you know, farts and so on) this, and other compounds of its kind, can help find signs of life on Mars or in the atmospheres of exoplanets. The linked work above explains that methanethiol may be involved in the origin of life in places with hydrothermal activity at low temperatures caused by serpentinization (a process that consumes water and releases heat). This process could take place on Mars, in icy oceans of moons or satellites, and in other smaller bodies, as well as on Earth.

Thus, detecting the presence of methyl mercaptan could be a tool for detecting signs of life. Although, honestly, we return to the usual: detecting a particular compound that we associate with the presence of life does not necessarily imply that there is life. There are many processes, in addition to farts, that can lead to the formation of methyl mercaptan. In this series of “flatulence in space” we always get to the same point: the origin of life.

And this because, dear friends, it seems that life, although it can be wonderful, sometimes stinks. 😉


Image 1: Space-filling model of the methanethiol molecule. Credits: Ben Mills.


List of molecules detected in space on the astrochymist web.

The methyl mercaptan on the “astrochymist” website.

Information on the toxicity of methyl mercaptan on the “Agency for Toxic Substances and Disease Registry” website of the Centers for Disease Control and Prevention (Atlanta, USA). Public Health Summary

Originally published in Spanish on the Naukas website: “Flatulencias espaciales (III) (2016/05/10).

The torus around a supermassive black hole, observed for the first time

Using the ALMA (Atacama Large Millimeter-Submillimeter Array) array, a team of researchers, led by Santiago García-Burillo (of the National Astronomical Observatory (OAN-IGN), Spain) has managed to observe, for the first time, the dust and gas torus surrounding a supermassive black hole, in this case the one at the center of galaxy NGC 1068 (also known as Messier 77).

The core of galaxy NGC 1068.

Active Galactic Nuclei (AGN) galaxies are those that harbor a supermassive black hole at their core with signs of recent activity. These types of black holes accrete material while emitting a large amount of energy over a wide spectrum of wavelengths. It is believed that all galaxies, at some point in their lives, can be active galaxies.

For a period of activity to be triggered, the central supermassive black hole must be “fed” and, for a long time, it has been postulated that the fuel should be stored on a dust and gas disc surrounding the black hole. Although the immediate environment of the black holes of active galaxies may be as bright as the entire galaxy that houses it, some of these nuclei appear to be hidden behind a ring-shaped structure of dust and gas, called a “torus”.

The torus (or doughnut) shape, adopted in many theoretical models, would explain many of the enigmatic and spectacular features observed in active galaxies. But, due to the great distance that separates us from these objects, to isolate that small structure we need advanced instrumentation and the use of interferometric techniques, capable of achieving a very high angular resolution [1].  This has finally been made possible by the ALMA (Atacama Large Millimeter/submillimeter Array) antenna array.  

This is the first time that a circumnuclear disc of this type -its composition, dust emission, gas distribution and even its movement- is clearly observed [2].

NGC 1068 or Messier 77

This galaxy is one of the most active and, at the same time, one of the closest to us (it is about 50 million light years away), so, for decades, it has been the subject of numerous observational studies that have tried to detect the presence of that disc of torus-shaped material at its center, surrounding the supermassive black hole.

For Santiago García-Burillo, astrophysicist at the National Astronomical Observatory (OAN-IGN), member of ASTROMOL and principal investigator of this work, “These observations are an evidence of what ALMA can do, managing to spatially detect and solve very small structures in nearby galaxies. We will be able to know more about the behavior of these discs and how they stabilize around the supermassive black holes, feeding them to create monsters whose mass can reach from millions to billions of times the mass of our Sun.”

These observations demonstrate the existence of these discs. However, the torus discovered in NGC1068 appears to be much more complex than expected. The next step will be to study other similar galaxies to see if this uncovered complexity is a common phenomenon in galaxies with active nuclei or whether, on the contrary, NGC 1068 is an exception.


[1] Better than 0.1″ (arcseconds).

2] The emission in the continuum of dust from the torus has been obtained, but, most notably, the torus has also been spatially resolved in the emission of molecular gas. To do this, the 6-5 rotational line of carbon monoxide (CO) was used as a dense gas tracer (n(H2)~1×105 cm-3). This allowed to derive the size of the torus (about 7-10 pc ~ 26 light-years in diameter) and study the kinematics of the gas, which turns out to be very complex: the gas would be expected to rotate regularly at these distances around the black hole, however, in addition to the gas disc appears to be praised, the gas has strong non-circular movements superimposed on rotation.

More information:

Paper: ALMA resolves the torus of NGC 1068: continuum and molecular line emission.

Other links:

NewScientist: Dusty doughnut around massive black hole spied for first time (Shannon Hall).


Image 1: The NASA/ESA Hubble Space Telescope has captured this vivid image of spiral galaxy Messier 77 — a galaxy in the constellation of Cetus, some 45 million light-years away from us. The streaks of red and blue in the image highlight pockets of star formation along the pinwheeling arms, with dark dust lanes stretching across the galaxy’s starry centre. The galaxy belongs to a class of galaxies known as Seyfert galaxies, which have highly ionised gas surrounding an intensely active centre. Credit: NASA/JPL-Caltech. Link to the original image.

Image 2: Emission on the continuum of the dust captured by ALMA on the circumnuclear disc of NGC1068 from scales of ~200 parsec ~ 600 light-years (panel-a) to the scales of the torus ~7-10 parsecs ~ 26 light-years (panels b and c).

Image 3: Emission (a) and speed field (b) of molecular gas detected by ALMA on the circumnuclear disc of NGC1068.