Press Release
The Soot Enshrouded End of a Sun-like Star
December 15, 2004
Image (96 KB) |
Object: Planetary Nebula BD +303639 Telescope: Subaru (Effective Aperture 8.2 m), Cassegrain Focus Instrument: Coronagraphic Imager with Adaptive Optics (CIAO) Filters: J(1.25 microns), H(1.65 microns), K(2.2 microns) Color Composition: J=Blue, H=Green, K=Red Observation Date: July 9, 2001 (UT) Exposure Time: 30 sec in each filter Filed of View: 10'' x 15'' Image Orientation: Top is North, Left is East Position: alpha=19h35m45.23s delta=+30deg 30'58.9'' (J2000) Constellation: Cygnus (the Swan) |
The Coronagraphic Imager with Adaptive
Optics (CIAO) on the Subaru telescope captured this near-infrared
(wavelengths of 1.25 - 2.2 microns) image of a star at
the end of its life. BD +303639 is a planetary nebula,
similar to the
Ring Nebula in the constellation Lyra, the Harp. It
is about five thousand light years from Earth in the direction
of the constellation Cygnus, the Swan. The surface of
the star in the center of the nebula sizzles at a temperature
of forty two thousand degrees Kelvin, and shines fifty
thousand times brighter than our Sun.
At the end of their lives, comparatively lightweight stars
like our Sun shed dust and gas which pile around the star.
BD +303639 rapidly puffed off its outer layers about nine
hundred years ago. This material, weighing almost a quarter
of the Sun, has now expanded into a shell one hundred
times more extended than the Solar System. The central
star illuminates the material which looks like a life
preserver from our point of view.
With visible light we can only see the light from the
central star scattering off the dust. In infrared light,
we can also see light emitted by the dust itself. CIAO
used a technique called adaptive optics, which removes
the twinkle of light due to turbulence in Earth's atmosphere,
to obtain an extraordinarily sharp image of the dust surrounding
the star. (Note 1)
Spectra of the central star from the Subaru telescope's
High Dispersion Sepctrogrtaph indicates that the sizzling
at the star's surface is generating large quantities of
carbon. This carbon is a likely ingredient of the dust
surrounding the star.
Shedding of material is an integral part of the life of
stars. "Although astronomers have been studying the
dust and gas surrounding stars of different ages and types,
we are only beginning to be able to observe and understand
detailed structures such those in BD +303639," says
Dr. Koji Murakawa, an astronomer at the Netherlands Foundation
for Research in Astronomy. Murakawa adds that "images
like these give us precious insight into the last moments
in a stars life."
Note 1: The coronagraph, a device that blocks the light from a bright central star, was not used to obtain this image.