Astronomy: First "close-up" of a star outside the Milky Way
So far, there have only been magnified images of a few stars that show more than one pixel. Now the first one from outside the Milky Way has been added.
The photograph on the left, an artistic reconstruction on the right
(Image: ESO/K. Ohnaka et al., L. Calçada)
A new instrument from the European Southern Observatory has succeeded for the first time in taking a "close-up" of a star outside the Milky Way. It shows the dying star WOH G64 in the Great Maggellanic Cloud and makes it clear that it has changed noticeably lately, writes the research institute. The responsible research team also discovered an egg-shaped cocoon surrounding the star using the Very Large Telescope Interferometer (VLTI). It is now exciting to find out the connection between the state of the star and the imminent supernova explosion.
Only a few stars more than a dot
The star that has now been photographed is a so-called "red supergiant" 160,000 light years away from us. This means that the star, which is 2000 times the size of our sun, is at the end of its development and – in astronomical terms – shortly before its final explosion as a supernova. This is another reason why it has long been of interest to astronomers, explains the team. However, in analyses from 2005 and 2007, WOH G64 was only resolved as a point source, like the vast majority of stars. Enlarged images have so far only been possible of around two dozen stars –, the best known of which is certainly Betelgeuse, all of which are in the Milky Way.
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WOH G64 is one of the most extreme stars of its kind, co-author Jacco van Loon from Keele University in the UK explains. Any change is therefore of interest. The team has now discovered that the appearance of the star has changed considerably since the earlier analyses. The research group believes that ejected material obscures the star from our point of view. As a result, its luminosity is becoming weaker and weaker and it is becoming increasingly difficult to image it – even for the GRAVITY instrument currently in use. However, future devices such as GRAVITY+ promise a remedy and a sustained view of the dying star. The close-up image is now presented in Astronomy and Astrophysics.
(mho)
