provide astronomers with this unprecedented view of its stars.
This has been made possible thanks to the
combination of two specific characteristics
of GeMS: First, the capability of operating
at near-infrared wavelengths (especially in
the K pass-band); second, an innovative and
revolutionary way to remove the distortions
(blurriness) that the Earth’s turbulent atmosphere inflicts on astronomical images.
To compensate for the degrading effects of
the Earth’s atmosphere, the GeMS system
uses three natural guide stars, a constellation of five laser guide stars, and multiple
deformable mirrors. The correction is so fine
that astronomers are provided with images
of unparalleled sharpness.
In the best K-band exposures of Liller 1, stellar images have an angular resolution of
only 75 milliarcseconds, just slightly larger
than the theoretical limit (known as the diffraction limit) of Gemini’s 8-meter mirror.
This means that GeMS almost perfectly corrected Earth’s atmospheric distortions.
The international research team published
the results in the June 15 issue of The Astrophysical Journal (volume 806, page 152).
The astro-ph version of the article can be
found here.
The results achieved on Liller 1 have been so
important that the research team is currently expanding their work to other globular
clusters, which promise to deliver even more
exciting science.
for instance, are old stars that mysteriously
appear younger than they should be; these
exotic stars may be formed by nearly headon collisions that cause the stars to merge,
mixing their nuclear fuel and restoking the
fire of the nuclear fusion. But collisions can
also involve binary systems, with the effect
of shrinking the initial size of the system,
promoting the two components to interact
and producing a variety of objects like lowmass X-ray binaries, millisecond pulsars, etc.
In particular, millisecond pulsars are old neutron stars in a binary system whose rotation
periods have been reaccelerated to milliseconds by matter accreting onto them from a
companion star. Astronomers suspect that
Liller 1 harbors a large population of these
exotic objects. Although no millisecond pulsar has been directly observed up to now,
the detection of intense gamma-ray emission (the most intense detected so far from
a globular cluster) suggests a large hidden
population. The Gemini observations confirm that this is possible.
“Indeed, our observations confirm Liller 1 as
one of the best ‘laboratories’ where the impact of star cluster dynamics on stellar evolution can be studied: It opens the window
to a sort of stellar sociology study, aimed at
measuring the impact of the reciprocal influence of stars when they are forced to live in
conditions of extreme crowding and stress,”
concluded Ferraro.
Additional information can be found at
http://www.cosmic-lab.eu/Cosmic-Lab/
Liller1.html
Background:
Stellar Collisions
Stellar collisions are important because
they can provide the key to understanding how certain exotic objects, which cannot be explained by the passive evolution
of single stars, originate. “Blue Stragglers,“
July 2015
GeminiFocus
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