ALMA explores a Cosmic Jellyfish
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ALMA explores a Cosmic Jellyfish

30 September, 2019 / Read time: 3 minutes

Scientific Paper

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 cnidaria 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 Desert at an altitude of 5000 meters. ALMA observes the night sky from this remote location to unlock the secrets of how the Universe — and its weird and wonderful residents, ESO 137-001 included — formed and evolved, revealing more about our cosmic origins.

Additional Information

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.


Credit:ALMA (ESO/NAOJ/NRAO), P. Jachym (Czech Academy of Sciences) et al.


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