[MGSA-L] New Greek observatory sheds light on old star

June Samaras june.samaras at gmail.com
Thu Feb 28 12:24:42 PST 2013


http://www.ras.org.uk/news-and-press/224-news-2013/2223-new-greek-observatory-sheds-light-on-old-star

New Greek observatory sheds light on old star


Wednesday, 27 February 2013 11:40


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 Pelοponnese 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. The researchers, Panos Boumis of the National
Observatory of Athens and John Meaburn of the University of
Manchester, publish the first scientific result from the telescope in
the journal Monthly Notices of the Royal Astronomical Society.

An image of the enclosure of the new 2.3-m Aristarchos telescope,
sited at Helmos Observatory. Credit: P. Boumis, National Observatory
of Athens. Click for a larger version of this image.
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. 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.
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
Space Telescope.
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. 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."

Science Contact

Dr Panayotis Boumis
Senior Researcher
Inst. Astronomy, Astrophysics, Space Applications & Remote Sensing
National Observatory of Athens,
Greece
Tel: +30 210 810 9162
Mob: +30 6946934309
ptb at astro.noa.gr

Media contact

Dr Robert Massey
Royal Astronomical Society
Tel: +44 (0)20 7734 3307 x214
Mob: +44 (0)794 124 8035
rm at ras.org.uk

Images

https://www.ras.org.uk/images/stories/press/telescope2.jpg
An image of the enclosure of the new 2.3-m Aristarchos telescope,
sited at Helmos Observatory. Credit: P. Boumis, National Observatory
of Athens
https://www.ras.org.uk/images/stories/press/kjpn8_col.jpg
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.
------------------------------------
June Samaras
2020 Old Station Rd
Streetsville,Ontario
Canada L5M 2V1
Tel : 905-542-1877
E-mail : june.samaras at gmail.com


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