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.
The
research is detailed in a paper to appear in the science journal Astronomy
and Astrophysics and was posted online.
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