Thursday, December 3, 2009

Trumpler 14 : New Image from MAD Telescope

"Young Star Cluster Trumpler 14 Revealed in Stunning Image"
Science News, ScienceDaily (December 3, 2009)

"The young star cluster Trumpler 14 is revealed in another stunning ESO image. The amount of exquisite detail seen in this portrait, which beautifully reveals the life of a large family of stars, is due to the Multi-conjugate Adaptive optics Demonstrator (MAD) on ESO's Very Large Telescope. Never before has such a large patch of sky been imaged using adaptive optics [1], a technique by which astronomers are able to remove most of the atmosphere's blurring effects.

"Noted for harbouring Eta Carinae -- one of the wildest and most massive stars in our galaxy -- the impressive Carina Nebula also houses a handful of massive clusters of young stars. The youngest of these stellar families is the Trumpler 14 star cluster, which is less than one million years old -- a blink of an eye in the Universe's history. This large open cluster is located some 8000 light-years away towards the constellation of Carina (the Keel).

"A team of astronomers, led by Hugues Sana, acquired astounding images of the central part of Trumpler 14 using the Multi-conjugate Adaptive optics Demonstrator (MAD, [2]) mounted on ESO's Very Large Telescope (VLT). Thanks to MAD, astronomers were able to remove most of the blurring effects of the atmosphere and thus obtain very sharp images. MAD performs this correction over a much larger patch of the sky than any other current adaptive optics instrument, allowing astronomers to make wider, crystal-clear images...."

This is a pretty big deal on two counts:
  • The Trumpler 14 star cluster puts a great many stars with similar origins, at a very early phase of their development, in a relatively small patch of sky.
  • That MAD telescope is a technological marvel, making it possible to make (some) observations from Earth's surface that normally are possible only for telescopes orbiting above Earth's atmosphere.
The ScienceDaily article explains just how densely-packed stars in Trumpler 14 are:

"...The astronomers counted about 2000 stars in their image, spanning the whole range from less than one tenth up to a factor of several tens of times the mass of our own Sun. And this in a region which is only about six light-years across, that is, less than twice the distance between the Sun and its closest stellar neighbour!..."

(While I'm at it, something to watch for in other places running this story: I've seen the size of Trumpler 14 (six light years across) described as 'less than the distance between the Sun and its closest stellar neighbor.' That's why, when I copy from another source, I do a digital cut-and-paste - and put quotes around the copied text. It's 'way too easy to leave something out, when re-keying something.)

Kudos to ScienceDaily, for the level of detail in their article - and for footnotes. I happen to know what adaptive optics are - but then, I've been following astronomy news for over four decades.

Bottom line about the article? It's the best coverage I found, about the new Templer 14 images.

With MAD Telescopes, You Don't Have to Go to Orbit: But It Helps

Some of the resources in "more," below are on Harvard's Chandra website. The Chandra observatory is a robot, orbiting about a third of the way from Earth to the Moon, and can "see" X-rays - which Earth's atmosphere filters out. (Top 10 Facts about Chandra," Chandra X-ray Observatory (CX0))

The Chandra X-ray Observatory is named after Subrahmanyan Chandrasekhar. If you haven't heard of him, you haven't been paying much attention to astrophysics. Which many people don't. Interestingly, although Dr. Chandrasekhar was born in India, "Subrahmanyan Chandrasekhar" is a regular American name. And has been since 1953, when Dr. Chandrasekhar became an American citizen.

(For what it's worth, my spellcheckers catch it when I misspell Chandrasekhar.)

From a micro-biography on the CXO website:

"...Trained as a physicist at Presidency College, in Madras, India and at the University of Cambridge, in England, he was one of the first scientists to combine the disciplines of physics and astronomy. Early in his career he demonstrated that there is an upper limit - now called the Chandrasekhar limit - to the mass of a white dwarf star...." (" Subrahmanyan Chandrasekhar / The Man Behind The Name" CXO website)

The big deal about the Chandra X-ray Observatory is that it can "see" wavelengths that don't reach the ground - even up where the ESO's MAD telescope is. On the other hand, it's a whole lot easier to get at ESO's equipment, if repairs are needed.

  • The Very Large Telescope Project
  • Trumpler 14
    • "Trumpler 14: Bright Young Stars Mix It Up"
      Chandra::Photo Album, Harvard-Smithsonian Center for Astrophysics (August 2005, revised February 20, 2009)
      • Dare I point this out? They're Americans:
        • "Operated for NASA by SAO [Smithsonian Astrophysical Observatory]
          "This site was developed with funding from NASA under Contract NAS8-03060."
    • As politically incorrect as it is to feel this way, I'm rather glad when my country does something right.
  • "The Eta Carinae Nebula and Trumpler 14"
    AAT (Anglo-Australian Observatory)
    • I'm glad when people in other countries do something right, too.
  • "Bright Young Stars in Trumpler 14"
    Universe Today (September 1, 2005)
    THE ASTROPHYSICAL JOURNAL, 549:578È589 (March 1, 2001)
    • This is a bit more technical than the other resources listed: but gives pretty good detail.
      • "H-R diagrams are presented for the very young galactic clusters Trumpler 14 and Trumpler 16, which are the two most populous clusters in the region of vigorous star formation surrounding η Carinae...."


"[1] Telescopes on the ground suffer from a blurring effect introduced by atmospheric turbulence. This turbulence causes the stars to twinkle in a way that delights poets but frustrates astronomers, since it smears out the fine details of the images. However, with adaptive optics techniques, this major drawback can be overcome so that the telescope produces images that are as sharp as theoretically possible, i.e. approaching conditions in space. Adaptive optics systems work by means of a computer-controlled deformable mirror that counteracts the image distortion introduced by atmospheric turbulence. It is based on real-time optical corrections computed at very high speed (several hundreds of times each second) from image data obtained by a wavefront sensor (a special camera) that monitors light from a reference star.

"[2] Present adaptive optics systems can only correct the effect of atmospheric turbulence in a very small region of the sky -- typically 15 arcseconds or less -- the correction degrading very quickly when moving away from the reference star. Engineers have therefore developed new techniques to overcome this limitation, one of which is multi-conjugate adaptive optics. MAD uses up to three stars instead of one as references to remove the blur caused by atmospheric turbulence over a field of view thirty times larger than that available to existing techniques (ESO PR 19/07)...."

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