New Image Reveals Nebula's Double Star Heart


This new image, centred on the B[e] star HD 87643, beautifully shows the extended nebula of gas and dust that reflects the light from the star. The nebula appears at the upper right. The image was released by the European Southern Observatory on Aug. 5, 2009. Credit: ESO

A new look at a distant nebula has revealed not one, but two stars locked in a cosmic dance that has shaped their dusty surroundings.

Astronomers with the European Southern Observatory used several telescopes to build the clearest image yet of a region of space around the odd star HD 87643, whose light reflects off surrounding material to illuminate it in a so-called reflection nebula of wispy tendrils of gas and dust. The star also appears to shape the nebula around it through solar winds and by regularly belching matter into space every 15 to 50 years.

Those ejections, astronomers said, may be caused by a companion star found to be circling the main star in a highly elliptical orbit and at a distance about 50 times larger than that separating the Earth and the sun. The Earth is typically about 93 million miles (150 million km) from the sun.

The two stars likely orbit each other about once every 20 to 50 years and may be encircled by a disc of dust, with the companion star triggering eruptions from HD 87643 whenever it draws near.

The star HD 87643 sits about 4,900 light-years from Earth in the constellation Carina, or the Keel. One light-year is the distance light travels in one year, or about six trillion miles (9.7 trillion km).

A team of researchers led by astronomer Florentin Millour used the European Southern Observatory's Very Large Telescope Interferometer in Paranal and the 2.2-meter telescope at the La Silla Observatory in Chile to observe the reflection nebula and its double star heart.

To build the close-up image of HD 87643, astronomers used adaptive optics to cancel out the interfering effects of Earth's atmosphere by making small changes in their telescope's mirror surface. They also used a wide field imaging camera to photograph the panoramic view of the star's surrounding nebula and stellar neighborhood.