Friday, February 23rd, 2018

Ho-hum or Omigosh?


New planet In a press release dated June 29, 2020, the Gemini Observatory announced the first confirmed planet in orbit around a sun-like star.

A planet only about eight times the mass of Jupiter has been confirmed orbiting a Sun-like star at over 300 times farther from the star than the Earth is from our Sun. The newly confirmed planet is the least massive planet known to orbit at such a great distance from its host star. The discovery utilized high-resolution adaptive optics technology at the Gemini Observatory to take direct images and spectra of the planet.

As with most such bland announcements, the words don’t do justice to the awe and wonder we might feel if we could truly appreciate what is going on here.

For instance, the Gemini Observatory itself is a unique astronomical observatory consisting of two, huge, 8.1-meter (27 ft) telescopes at different sites in Hawaii and Chile. Together, the twin Gemini telescopes provide almost complete coverage of both the northern and southern skies. They are currently among the largest and most advanced optical/infrared telescopes available to astronomers. This is what it took to finally confirm that the apparent solar system first observed in 2008 was that in fact.

Consider that it is far from a trivial matter to determine whether that tiny speck above the distant star is really locked in an orbit around the star or not. Telescopes have no depth perception. That speck of a planet might have been many light-years nearer or farther from the larger star. It took a series of proper motion plots of the pair over a period of several years to confirm the existence of orbital motion. That may not sound impressive to you, but to this quasi-scientific mind it is.

The image above shows that the sun itself appears very tiny as viewed by even the largest telescopes, as attested by the little scale bar at the lower left, which is only one arc-minute wide. (Let’s see now, one degree of arc divided by 60…) The distant star is so tiny that resolving it from its even smaller planet is impossible using an earth-mounted telescope due to turbulence in the earth’s atmosphere.

So how did they do it? A technique called adaptive optics is used to improve the resolution by slightly distorting the shape of a secondary mirror many times a second to compensate for the atmosphere’s distortions. Sound impossible? Well it was until not too many years ago. Now, the view from earth using adaptive optics rivals the view from orbiting telescopes well above the distorting effects of the earth’s atmosphere. Amazing, is it not?

Some more details: The host star-Sun is about 500 light-years away in a group of young stars called the Upper Scorpius association that formed about five million years ago. The new-born planet in orbit is slowly cooling down by radiating infrared light, the light that is being observed by the Gemini Observatory. In billions of years, the planet will eventually reach a temperature similar to that of Jupiter.

Dave, which he will have to take that last assertion on trust.


2 Responses to “Ho-hum or Omigosh?”
  1. Linda says:

    My vote… Omigosh!

  2. Dave says:

    Ditto. Having had to sweat out the design of servo systems in the past, the idea of warping the shape of a mirror in anticipation of wavering atmospheric turbulence is almost beyond my ken. Maybe not almost. There is a diagram of the hardware to accomplish this in the companion book to Alex’s astronomy course, which mainly served to increase my wonder.

    May we never get to the point of ho-hum in the face of such accomplishments.

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