Soap bubbles and jellyfish galaxies
Using the detailed eyes of the Atacama Large Millimeter/submillimeter Array (ALMA) and ESO’s Very Large Telescope (VLT), astronomers have mapped the intense tails of a cosmic jellyfish: a number of knotty streams of gas spewing outwards from a spiral galaxy named ESO 137-001. This celestial cnidarian is shown here in beautiful detail. The various elements making up this image were captured by different telescopes. The galaxy and its surroundings were imaged by the NASA/ESA Hubble Space Telescope; its tails, which trace streams of hydrogen and show up in hues of bright purple, by the MUSE instrument mounted on the VLT; and bright hotspots of carbon dioxide emission from within the system, which show up as flares of orange-red, were spotted by ALMA. These tails are caused by a dramatic phenomenon known as ram-pressure stripping. The space between galaxies in a cluster is not empty, but full of material that acts like a viscous fluid. As a galaxy travels through this resistant environment, gas is stripped out of the galaxy to form a wake that creates beautiful, intricate systems such as that seen here around ESO 137-001 (which resides in the Norma galaxy cluster). The direction and position of the tail shed light on the way in which the galaxy is moving — with galaxies usually falling towards the centre of the cluster itself. This image offers the first high-resolution map of the cold molecular gas lurking within a ram-pressure stripped system. ESO 137-001 is one of the nearest jellyfish galaxies to Earth, and is particularly interesting because its long, extended tails of gas contain features known as ‘fireballs’: bursts of star formation. The precise mechanisms governing how stars form within jellyfish tails are mysterious, and this map thus provides a new window onto the conditions needed for new stars to form in such intense, changeable environments.  The ALMA array comprises 66 antennas, and is located on the Chajinator plateau in the Chilean Atacama Dese

Soap bubbles and jellyfish galaxies

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You probably know how to make soap bubbles. First, you put a ring of plastic or metal into a soap bath, and gently pull it out again. The ring is now filled with a thin film of soap. If you hold the ring still, nothing will happen. But if you start walking, holding the ring above your head, it leaves a beautiful trail of soap bubbles behind.

The reason, of course, is the pressure of the air. It isn’t hard at all to move the ring itself through the air. However, the feeble soap film is easily pushed back by the air that you’re moving through. That’s why the soap is blown out of the ring.

In a remote cluster of galaxies, astronomers have studied a cosmic equivalent of a soap bubble toy. The space between the galaxies in the cluster is filled with a very hot, tenuous gas – that’s the ‘air’. One of the galaxies in the cluster is moving through this gas at a pretty high velocity – that’s the ‘ring’. As a result, the thin gas in the galaxy – the ‘soap film’ – is pushed out and left behind. Astronomers call this process ‘ram-pressure stripping’.

The galaxy and its cosmic ‘soap bubbles’ have been imaged in detail by the Hubble Space Telescope. Together, they look a little bit like a jellyfish, with thin ‘tails’ trailing behind. Using the European Very Large Telescope in Chile, astronomers have also detected the glow of hot hydrogen gas in the tails.

Now, ALMA has also studied the jellyfish galaxy. ALMA detected the submillimeter radiation from carbon monoxide molecules within the gas flows (shown as orange knots in the image). It is the first time that cold, molecular gas has been detected in a ram-pressure stripped galaxy.

The new observations provide scientists with more information on the motion of the galaxy, and on the interaction between the galaxy and the tenuous gas in the cluster. They may also shed light on the unexplained bursts of star formation that occur in the ‘tails’.


The jellyfish galaxy studied by ALMA is officially known as ESO 137-001. The galaxy is part of the Norma cluster. The Norma cluster is named after the southern constellation Norma, in which it is located, at a distance of some 220 million light-years. The cluster contains many hundreds of galaxies. ESO 137-001 is moving towards the center of the cluster at a velocity of seven million kilometers per hour. As a result of this fast motion, gas is pushed out of the galaxy, forming a 250,000 light-year long tail.


The ALMA observations of carbon monoxide in the tail of the jellyfish galaxy ESO 137-001 were carried out by Pavel Jáchym and his colleagues. Pavel is an astronomer at the Czech Academy of Sciences in Prague. He teamed up with ten other astronomers, from the United States, Canada, the United Kingdom, Australia, Portugal, and France. The new observations are published in The Astrophysical Journal.

Check this in ALMA site