Nav: Home

A blue whirlpool in The River

August 01, 2012

The galaxy NGC 1187 [1] is seen almost face-on, which gives us a good view of its spiral structure. About half a dozen prominent spiral arms can be seen, each containing large amounts of gas and dust. The bluish features in the spiral arms indicate the presence of young stars born out of clouds of interstellar gas.

Looking towards the central regions, we see the bulge of the galaxy glowing yellow. This part of the galaxy is mostly made up of old stars, gas and dust. In the case of NGC 1187, rather than a round bulge, there is a subtle central bar structure. Such bar features are thought to act as mechanisms that channel gas from the spiral arms to the centre, enhancing star formation there.

Around the outside of the galaxy many much fainter and more distant galaxies can also be seen. Some even shine right through the disc of NGC 1187 itself. Their mostly reddish hues contrast with the pale blue star clusters of the much closer object.

NGC 1187 looks tranquil and unchanging, but it has hosted two supernovae explosions since 1982. A supernova is a violent stellar explosion, resulting from the death of either a massive star or a white dwarf in a binary system [2]. Supernovae are amongst the most energetic events in the Universe and are so bright that they often briefly outshine an entire galaxy before fading from view over several weeks or months. During this short period a supernova can radiate as much energy as the Sun is expected to emit over its entire life span.

In October 1982, the first supernova seen in NGC 1187 -- SN 1982R [3] was discovered at ESO's La Silla Observatory and more recently, in 2007, the amateur astronomer Berto Monard in South Africa spotted another supernova in this galaxy -- SN 2007Y. A team of astronomers subsequently performed a detailed study and monitored SN 2007Y for about a year using many different telescopes [4]. This new image of NGC 1187 was created from observations taken as part of this study and the supernova can be seen, long after the time of maximum brightness, near the bottom of the image.

These data were acquired using the FORS1 instrument attached to the ESO's Very Large Telescope at the Paranal Observatory in Chile.



[1] This galaxy was discovered in England by William Herschel in 1784.

[2] One class of supernova explosions occur at the end of a massive star's lifetime -- stars more massive than eight solar masses -- when its nuclear fuel is exhausted and the star is not longer able to counteract gravitational collapse, producing a violent explosion. Alternatively, a supernova explosion can also occur in a binary star system, in which a carbon-oxygen white dwarf is pulling matter from a higher-mass companion star. If enough matter is transferred, the star will begin to collapse, producing the supernova explosion.

[3] The International Astronomical Union is responsible for naming supernovae after they are discovered. The name is formed by the year of discovery, followed by a one or two letter designation. The first 26 supernovae of the year get an upper case letter from A to Z. Subsequent supernovae are designated with two lower-case letters.

[4] Further information about SN 2007Y is available in a paper by Stritzinger et al. (

More information

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".


Photos of the VLT:

Other images taken with the VLT:


Richard Hook
ESO, La Silla, Paranal, E-ELT and Survey Telescopes Public
Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591

The big star that couldn't become a supernova
For the first time in history, astronomers have been able to watch as a dying star was reborn as a black hole.
Seeing quadruple: Four images of the same supernova, a rare find
Galaxies bend light through an effect called gravitational lensing that helps astronomers peer deeper into the cosmos.
Explosive material: The making of a supernova
Pre-supernova stars may show signs of instability for months before the big explosion
Search for stellar survivor of a supernova explosion
Astronomers have used the NASA/ESA Hubble Space Telescope to observe the remnant of a supernova explosion in the Large Magellanic Cloud.
Wispy remains of supernova explosion hide possible 'survivor'
This image, taken with NASA's Hubble Space Telescope, shows the supernova remnant SNR 0509-68.7, also known as N103B.
The dawn of a new era for Supernova 1987a
Three decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years.
The supernova that wasn't: A tale of 3 cosmic eruptions
Long-term observations with the Hubble Space Telescope revealed that Eta Carinae, a very massive star system that has puzzled astronomers since it erupted in a supernova-like event in the mid 19th century, has a past that's much more violent than they thought.
Blue is an indicator of first star's supernova explosions
An international collaboration led by the Kavli Institute for the Physics and Mathematics of the Universe have discovered that the color of supernovae during a specific phase could be an indicator for detecting the most distant and oldest supernovae in the Universe -- more than 13 billion years old.
Nearby supernova ashes continue to rain on Earth
Traces of 60Fe detected in space indicate that a nearby supernova occurred within the last few million years.
Supernova iron found on the moon
Approximately two million years ago a star exploded in a supernova close to our solar system: Its traces can still be found today in the form of an iron isotope found on the ocean floor.

Best Science Podcasts 2017

We have hand picked the best science podcasts for 2017. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.

Now Playing: Radiolab

Truth Trolls
Today, a third story of folks relentlessly searching for the truth. But this time, the truth seekers are an unlikely bunch... internet trolls.

Now Playing: TED Radio Hour

Rethinking School
For most of modern history, humans have placed smaller humans in institutions called schools. But what parts of this model still work? And what must change? This hour, TED speakers rethink education.TED speakers include teacher Tyler DeWitt, social entrepreneur Sal Khan, international education expert Andreas Schleicher, and educator Linda Cliatt-Wayman.