Continuing a tradition stretching back more than 25 centuries, astronomers have used the new 2.3-m 'Aristarchos'
telescope, sited at Helmos Observatory (2340m high) in the Peloponnese Mountains in Greece, to determine the
distance to and history of an enigmatic stellar system, discovering it to likely be a binary star cocooned
within an exotic nebula.
Stars of a similar mass to the Sun end their lives by ejecting much of their outer atmosphere into space, leaving
behind a remnant core that eventually becomes a so called white dwarf.
Aristarchos Telescope located at the top of Chelmos Mountain in Achaia, Kalavryta, Greece (altitude: 2340m/7677ft.)
The shells of ejected material sometimes have the superficial appearance of planets so were named planetary nebulae.
Astronomers can study the motion and appearance of the material in planetary nebulae to deduce how the remnant stars have changed over time.
Click on image to enlarge
Bipolar Planetary Nebula KjPn8 (PN G112.5-00.1)
KjPn8 (also known as PN G112.5-00.1) is located in the constellation of Cassiopeia.
In the 1950s the planetary nebula KjPn8 was discovered on Palomar Observatory Sky Survey plates. Follow up work
in the 1990s by Mexican astronomers at the San Pedro Martir Observatory led to the discovery of giant lobes around
the system, one quarter of a degree across, while in 2000 the central star was finally revealed by the Hubble
Dr Boumis and Prof. Meaburn set out to study this system, installing a narrowband imaging camera on the Aristarchos
telescope, the largest aperture instrument in south-eastern Europe, to measure the expansion more accurately.
By measuring the velocity and increasing size of the expanding material, the two scientists were able to deduce
the distance to the system and date the history of the three ejected lobes.
They found that KjPn8 is around 6000 light years away and that the material was thrown out in three phases 3200,
7200 and 50000 years ago.
The inner lobe of material is expanding at 334 km per second, suggesting it originates in an Intermediate
Luminosity Optical Transient (ILOT) event.
ILOTs are caused by the transfer of material from a massive star to
its less massive companion, in turn creating jets that flow in different directions.
Click on image to enlarge
An image of the giant lobes of the planetary nebula KjPn 8 in the light of the emission
lines of hydrogen and singly ionised nitrogen, obtained with the narrowband camera on the new 2.3-m
Aristarchos telescope. Detailed measurements of the lobes have allowed the determination of their
expansion velocity, distance and ages. The results indicate their origin in a remarkable eruptive
binary system. (Credit: P. Boumis / J. Meaburn)
Boumis and Meaburn believe that the core of KjPn8 is therefore a binary system, where every so often ILOT
events lead to the ejection of material at high speed.
Dr Boumis is delighted to see the first results from the new telescope giving clues to the history of such an
intriguing system. He comments: "Greece is one of the global birthplaces of astronomy, so it is fitting that
research into the wider universe continues in the 21st century.
With the new telescope we expect to contribute to that global effort for many years to come."