A recent
image taken by the Hubble Space Telescope reveals the perfect dust laboratory
in the sky and could help astronomers pin down the raw ingredients needed to
give birth to baby stars.
The stellar
photo is a composite of four images taken with different filters by Hubble's Advanced
Camera for Surveys. The resulting close-up shot reveals the northwest region of
the Iris Nebula, or NGC 7023. The nebula is a region of star formation that
lies about 1,400 light-years away in the constellation of Cepheus. (A light-year
is the distance light will travel in a year, which is about 6 trillion miles,
or 10 trillion km).
The image
shows billowing mounds of cosmic dust. Such dust is made up of tiny particles
of solid matter ranging in size from 10 to 100 times smaller than the dust
grains you might find blanketing household furniture on terra firma.
The
scientists were particularly interested in parts of the nebula that appeared
redder than expected. Considered a reflection nebula, NGC 7023 scatters light
from a massive nearby star, which in this case is a star called HD 200775
that's 10 times the mass of the sun. Typically, reflection nebulae appear blue,
because dust grains scatter blue light more efficiently than red.
(The other
variety of nebula, called emission nebulae, are hot enough to emit light
themselves and tend to appear red.)
Some
hydrocarbon-based compound must be causing these dusty filaments to take on the
red tinge, the researchers figure.
In addition
to studying the detailed Hubble image, the astronomers also used Hubble's Near
Infrared Camera and Multi-Object Spectrometer instrument to try to determine the
chemical make-up of the nebula.
In general,
where there are clumps of dust, stars can sprout up as the material collapses
inward due to gravity. Over time if the clump gets massive enough, it ignites nuclear
fusion, at which point a full-fledged star is born. And so the results could
also add to knowledge of star birth.
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