The Argo’s hidden cargo
Copyright: JAXA
Copyright: JAXA
The constellation of the great ship Argo Navis used to bob along the
watery southern horizon of the Mediterranean during times of antiquity.
Said
to represent the ship used by Jason and the Argonauts in the quest for
the Golden Fleece, it was included by Greek astronomer Ptolemy in his
2nd century AD list of the constellations.
French star-mapper
Nicolas Louis de Lacaille split the giant constellation into three
pieces in 1752 and this image shows Carina, the keel of the ship. Taken
by Japan’s Akari space observatory, it shows a hidden cargo:
star-forming dust.
This dust is part of the interstellar medium,
which also contains gas. The bright knots reveal dense cores, just a few
tenths of a light-year across. These dusty cocoons are where gravity is
incubating new stars. They are invisible at optical wavelengths because
the dust blocks the light from escaping.
However, the dust’s low
temperature means it gives off far-infrared radiation, making it visible
to the special detectors on Akari.
This false-colour image,
spanning 20x15°, is constructed from three far-infrared bands: blue
represents 65 micrometres, green shows 90 micrometres and red codes the
140 micrometre wavelength. The image is part of Akari’s recently
released all-sky survey.
This
is the first far-infrared all-sky survey since the Infrared
Astronomical Satellite (IRAS) was launched by the US, the UK and the
Netherlands in 1983. IRAS’s final release of image data was made in 1993
and astronomers have been using it ever since.
Akari’s all-sky survey is both higher resolution and contains longer wavelengths than the IRAS survey.
Akari
observed more than 99% of the sky over a period of 16 months. The
all-sky images have a resolution of 1–1.5 arcminutes (0.017–0.025º), in
four wavelengths: 65, 90, 140 and 160 micrometres.
Akari was the
second space mission for infrared astronomy from the Institute of Space
and Astronautical Science of the JAXA Japan Aerospace Exploration
Agency, this time with ESA’s participation.
Source: ESA
