Keck Telescope

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There are two Keck telescopes – Keck I and Keck II; together they make up the W.M. Keck Observatory, though strictly speaking the observatory is a great deal more than just the telescopes (there’s all the instrumentation, especially the interferometer, the staff, support facilities, etc, etc, etc.).

William Myron Keck (1880-1964) established a philanthropic foundation in 1954, to support scientific discoveries and new technologies. One project funded was the first Keck telescope, which was quite revolutionary at the time. Not only was it the largest optical telescope (and it still is) – it’s 10 meters in diameter – but is made up of 36 hexagonal segments, the manufacture of which required several breakthroughs … and all 36 are kept in line by a system of sensors and actuators which adjusts their position twice a second. Keck I saw first light in 1993. Like nearly all modern, large optical telescopes, the Keck telescopes are alt-azimuth. Fun fact: to keep the telescope at an optimal working temperature – no cool-down period during the evening – giant aircons work flat out during the day.

The Keck telescopes are on the summit of Hawaii’s Mauna Kea, where the air is nearly always clear, dry, and not turbulent (the seeing is, routinely, below 1″); an ideal site for not only optical astronomy, but also infrared.

The second Keck telescope – Keck II – saw first light in 1996, but its real day of glory came in 1999, when one of the first adaptive optics (AO) systems was installed on it (the first installed on a large telescope).

2004 saw another first for the Keck telescope – a laser guide star AO system, which gives the Keck telescopes a resolution at least as good as the Hubble Space Telescope’s (in the infrared)!

And in 2005 the two Keck telescopes operated together, as an interferometer; yet another first.

To learn more, I suggest that you start with the official W.M. Keck Observatory website! Revolution in Telescope Design Debuts at Keck After Birth Here is a 1992 Lawrence Berkeley Lab article which captures some the excitement of those early days; and The Keck Telescopes viewed from the North puts the Keck telescopes in the Mauna Kea context.

Universe Today has covered the Keck telescopes, many times, in many different ways; for example, Keck Uses Adaptive Optics for the First Time, Binary Icy Asteroid in Jupiter’s Orbit, and New Technique Finds Farthest Supernovae.

Astronomy Cast has a couple of episodes on the Keck telescopes; check them out! The Rise of the Supertelescopes, and Adaptive Optics.

Cool – Literally – Extrasolar Planet Imaged

Yet another planet outside of our Solar System has been directly imaged, bumping the list up past ten. Given that the first visible light image of an extrasolar planet was taken a little more than a year ago, the list is growing pretty fast. The newest one, planet GJ 758 B is also the coolest directly imaged planet, measuring 600 degrees Kelvin, and it orbits a star that is much like our own Sun. GJ 758 B has a mass of between 10-40 times that of Jupiter, making it either a really big planet or a small brown dwarf.

Unlike many of the other directly imaged planets, GJ 758 B resides in a system remarkably like our own Solar System – the star at the center is Sun-like, and the orbit of the planet is at least the same distance from its star as Neptune is from our own. Current observations put the distance at 29 astronomical units.

“The discovery of GJ 758 B, an extrasolar planet or brown dwarf orbiting a star that is similar to our own sun, gives us an insight into the diversity of substellar objects that may form around Solar-type stars,” said Dr. Joseph Carson, from the Max Planck Institute for Astronomy. “This in turn helps show how our own Solar system, and the environments that are conducive to life, are just one of many scenarios that may be the outcome of planet or brown dwarf formation around Sun-like stars.”

Another object, labeled “C?” in the image above, could potentially be another companion to the star. Further observations will be required to determine whether the object in fact orbits the star or is merely another star in the background of the image which is not part of the system.

The mass of the star still has yet to be exactly determined, thus the 10-40 Jupiter mass range. It is 600 degrees Kelvin, which corresponds to 326 Celsius and 620 Fahrenheit, about the hottest temperature that a conventional oven can reach. Though this may seem hot, it’s actually pretty cool for an extrasolar planet. Even though it is so far away from its Sun that, like Neptune, it receives very little warmth from the star it orbits, GJ 758 B is in a stage of formation where the contraction of the planet due to gravity is converted into heat.

A size comparison of the GJ 758 system and corresponding members of our own Solar System, with the Earth for reference. Image Credit: Credit: MPIA/C. Thalmann
A size comparison of the GJ 758 system and corresponding members of our own Solar System, with the Earth for reference. Image Credit: Credit: MPIA/C. Thalmann

Dr. Markus Janson from the University of Toronto, a co-author of the paper announcing the imaging, said, “This is also why the mass of the companion is not well known: The measured infrared brightness could come from a 700 million year old planet of 10 Jupiter masses just as well as from a 8700 million year old companion of 40 Jupiter masses.” The paper detailing the results will be published in Astrophysical Journal Letters, but is available here on Arxiv.

The planet was imaged using the Subaru Telescope’s new High Contrast Instrument for the Subaru next generation Adaptive Optics (HiCIAO) instrument, which utilizes the technology of adaptive optics to eliminate the interference of our atmosphere that blurs images in ground-based telescopes. The imaging of GJ 758 B is part of the commissioning run of the HiCIAO instrument, which plans to take a larger survey to detect extrasolar planets and circumstellar disks in the next five years.

Source: Max-Planck Institute for Astronomy