Sunday, November 15, 2015

Lyra - Gliese 758 and Subaru Telescope

The Star
Gliese 758 is a 6th magnitude Sun-like star with 97% of the Sun's mass and 88% of the radius of the Sun. Parallax measurements from the Hipparcos mission give it an estimated distance of around 51.4 light-years (15.8 parsecs) from Earth

The spectrum matches a stellar classification of G8V, identifying it as a G-type main sequence star that is generating energy through the nuclear fusion of hydrogen at its core. It is radiating this energy into space from its outer envelope at an effective temperature of 5425 K.

Estimates of its age put it at about 7.7–8.7 billion years old, although some measurements give it an age as low as 720 million years. The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, are 51% higher than in the Sun.

Are Gliese 759 b and c planets?
In November 2009, a team using the HiCIAO instrument of the Subaru Telescope imaged a substellar companion orbiting the star. This object, designated Gliese 758 b, was estimated to be of approximately 10-40 Jupiter masses.

A second candidate object was also detected, which was given the designation Gliese 758 C. Follow-up studies of the system suggested the mass range of Gliese 758 b, indicating it to be a companion with approximately 30 to 40 Jupiter masses and revealed that Gliese 758 C is a background star which is not physically associated with the Gliese 758 system.

On the other hand, a younger age was suggested from the kinematic stellar grouping.

Subaru Telescope

"MaunaKea Subaru" by Denys (fr) - Own work. Licensed under CC BY 3.0 via Commons
Subaru Telescope  is the 8.2 meter flagship telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in the world from its commission 1999 until 2005. Wikipedia

The large single mirror for Subaru was cast by Corning and polished at Contraves Brashear Systems in Pennsylvania.

One of the many instruments is High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO) infrared camera for hunting planets around other stars.

Subaru Telescope official website

List of worlds largest reflecting telescopes

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