Posted by Davin Flateau on 1 Jun 2005 at 12:12 pm.
Filed under Astronomy.
Stars spin. For instance, our own sun takes about a month to rotate , but that’s a snail’s pace compared to some. Pulsars, the leftover cores of exploded stars, can spin hundreds of times a second. This rotational energy changes the shape of a star from spherical to somewhat egg-shaped. Actually measuring the exact shape of stars in the Universe isn’t easy because of the great distances involved. Even to powerful telescopes, stars usually appear as just pinpoints of light.
But thanks to an amazing natural phenomenon, nature has created its own telescope, one powerful enough to let us see the smallest details in the Universe. Astronomers have shown that even from thousands of light years away, we can measure the actual shapes of distant stars.
The phenomenon that made this possible is called microlensing. When a massive object appears in front of another object, the gravity from the foreground object can bend and magnify the light from the background object (Einstein predicted this might happen all the way back in 1936). This event only lasts a short time, and the alignment of the two objects must be exact. Luckily, there are plenty of stars and galaxies, so astronomers patiently watch the skies for these “lensing” events to occur.
In 2002, a binary star moved in front of a star 16,000 light years away, twisting and magnifying the faint pinpoint of light. Together with ground based observations and the Hubble Space Telescope, astronomers were able to unwrap the magnified light of the background star and extract its shape – almost, but not quite, spherical.
Microlensing events are emerging to be a powerful astronomical tool. Recently, astronomers announced that a similar microlensing event led to the discovery of planet around a star 15,000 light years away (the discovery was assisted by observations from amateur astronomers).
Davin Flateau
