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Wolf-Rayet star WR124 and the surrounding nebula M1-67. Credit:
Yves Grosdidier (University of Montreal and Observatoire de Strasbourg),
Anthony Moffat (Universitie de Montreal), Gilles Joncas (Universite
Laval), Agnes Acker (Observatoire de Strasbourg), and NASA
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In 1998, the Hubble Space Telescope website published a spectacular image of the
turbulent and chaotic cloud of gas surrounding the massive star WR124. The news
release was accompanied by the following caption:
Resembling an aerial fireworks explosion, this dramatic NASA Hubble Space
Telescope picture of the energetic star WR124 reveals it is surrounded by hot
clumps of gas being ejected into space at speeds of over 100,000 miles per
hour.
Also remarkable are vast arcs of glowing gas around the star,
which are resolved into filamentary, chaotic substructures, yet with no
overall global shell structure. Though the existence of clumps in the winds of
hot stars has been deduced through spectroscopic observations of their inner
winds, Hubble resolves them directly in the nebula M1-67 around WR124 as 100
billion-mile wide glowing gas blobs. Each blob is about 30 times the mass of
the Earth.
The massive, hot central star is known as a Wolf-Rayet
star. This extremely rare and short-lived class of super-hot star (in this
case 50,000 degrees Kelvin) is going through a violent, transitional phase
characterized by the fierce ejection of mass. The blobs may result from the
furious stellar wind that does not flow smoothly into space but has
instabilities which make it clumpy.
The surrounding nebula is
estimated to be no older than 10,000 years, which means that it is so young it
has not yet slammed into the gasses comprising the surrounding interstellar
medium.
As the blobs cool they will eventually dissipate into space
and so don't pose any threat to neighboring stars.
The star is
15,000 light-years away, located in the constellation Sagittarius. The picture
was taken with Hubble's Wide Field Planetary Camera 2 in March 1997. The image
is false-colored to reveal details in the nebula's structure.
About ten years later, the same object was imaged with the
Very Large Telescope, from the Atacama Desert in Chile.
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WR124 and its nebula, called M1-67, imaged with the VLT. Credit:
ESO
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The picture release, published on December 2009 on the European Southern
Observatory website and ironically titled 'Gone with the Wind', contained the
following caption:
M1-67 is the youngest wind-nebula around a Wolf-Rayet star, called WR124, in
our Galaxy. These Wolf-Rayet stars start their lives with dozens of times
the mass of our Sun, but loose most of it through a powerful wind, which is
ultimately responsible for the formation of the nebula.
Ten years
ago, Hubble Space Telescope observations revealed a wealth of small knots
and substructures inside the nebula. The same team, led by Cédric Foellmi
(ESO), has now used ESO's Very Large Telescope (VLT) to watch how these
structures have evolved and what they can teach us about stellar winds,
their chemistry, and how they mix with the surrounding interstellar medium,
before the star will eventually blow everything away in a fiery supernova
explosion.
The image is based on FORS1 data obtained by the
Paranal Science team with the VLT through 2 wide (B and V) and 3 narrow-band
filters.
Sources:
