XMM-Newton and Hubble view of Jupiter’s Ghost
Copyright: ESA/XMM-Newton & Y.-H.
Chu/R.A. Gruendl/M.A. Guerrero/N. Ruiz (X-ray); NASA/ESA Hubble Space
Telescope & A. Hajian/B. Balick (optical)
Names of astronomical objects are often ambiguous, especially when
the historical designation of a certain class of celestial body preceded
their physical understanding and was based on their appearance in the
sky.
A notoriously abstruse case of nomenclature is that of
planetary nebulas, the picturesque remains of low- and intermediate-mass
stars. In contrast to what happens to their more massive counterparts,
stars with masses from 0.8 to 8 times that of the Sun do not end their
life exploding as powerful supernovas but peacefully puff up, releasing
their outer layers in the surrounding space and creating beautifully
shaped clouds in the process.
Although these stellar demises have
nothing to do with planets, astronomers in the 18th century, who first
noticed them, were baffled by their roundish appearance, and gave them
the misleading name of planetary nebulas.
And just to make it more
complicated, the planetary nebula shown in this image carries an even
more peculiar name. Since it spans a disc on the sky roughly as large as
that covered by the planet Jupiter, it received the curious moniker
Jupiter’s Ghost. Of course, this object is also known through its
catalogue designations, the most recent of which, since the late 19th
century, is NGC 3242.
The image reveals how mighty winds released
by the dying star – the white dwarf star at the centre – are shaping the
double-shell structure of the nebula. The blue glow filling the inner
bubble represents X-ray emission from hot gas, heated up to over two
million degrees by shocks in the fast stellar winds, gusting at about
2400 km/s against the ambient gas.
The green glow marks cooler
concentrations of gas seen in optical light through the emission of
oxygen, revealing the edge of the inner shell in contrast to the more
diffuse gas making up the outer shell. The two flame-shaped features,
visible in red to the upper right and lower left of the inner bubble,
are pockets of even cooler gas, seen also in optical light through the
emission of nitrogen.
Jupiter's Ghost lies some 3000 light-years away, and it is visible in the southern constellation Hydra, the water snake.
This
image combines X-ray data collected in 2003 by ESA’s XMM-Newton (blue)
with optical observations from the NASA/ESA Hubble Space Telescope
(green and red). It was first published on the XMM-Newton image gallery.
Source: ESA - Space Images
