The NASA/ESA Hubble Space Telescope has imaged a set of enigmatic quasar ghosts — ethereal green objects which mark the graves of these objects that flickered to life and then faded. The eight unusual looped structures orbit their host galaxies and glow in a bright and eerie goblin-green hue. They offer new insights into the turbulent pasts of these galaxies.
Hubble Space Telescope has discovered manifestations from the remote past, bright streams of gas, which look like immense looped objects glowing green, once ionized by quasars that no longer exist.
The telescope, which will turn 25 in 20 days, has taken photos of eight unusual space objects glowing emerald in the depths of space. Light emitting space areas dubbed ‘Hanny’s Voorwerp’ are tens of thousands of light years across.
The first object of this kind was spotted by Dutch schoolteacher Hanny van Arkel in 2007.
The ethereal wisps in these images were illuminated, perhaps briefly, by a blast of radiation from a quasar — a very luminous and compact region that surrounds a supermassive black hole at the center of a galaxy. Galactic material falls inwards towards the central black hole, growing hotter and hotter, forming a bright and brilliant quasar with powerful jets of particles and energy beaming above and below the disc of infalling matter.
In each of these eight images a quasar beam has caused once-invisible filaments in deep space to glow through a process called photoionisation. Oxygen, helium, nitrogen, sulphur and neon in the filaments absorb light from the quasar and slowly re-emit it over many thousands of years. Their unmistakable emerald hue is caused by ionised oxygen, which glows green.
hese objects were found in a spin-off of the Galaxy Zoo project, in which about 200 volunteers examined over 16 000 galaxy images in the SDSS to identify the best candidates for clouds similar to Hanny’s Voorwerp. A team of researchers analysed these and found a total of twenty galaxies that had gas ionised by quasars. Their results appear in a paper in the Astronomical Journal.
Source : RT , Spacetelescope.org