Distance to neighbor galaxy measured more accurately

March 8, 2013  |   |  2 Comments
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Artist’s impression of eclipsing binary (courtesy of European Southern Observatory)

Artist’s impression of eclipsing binary (courtesy of European Southern Observatory)

After nearly a decade of careful observations, an international team of astronomers has measured the distance to our neighboring galaxy, the Large Magellanic Cloud, more accurately than ever before. Astronomers Rolf-Peter Kudritzki and Fabio Bresolin, from the University of Hawaiʻi at Mānoa’s Institute for Astronomy, are part of that team. These results appear in the March 7 issue of the journal Nature.

Astronomers ascertain the scale of the universe by first measuring the distances to close-by objects and then using them as standard candles—objects of known brightness—to pin down distances farther and farther out in the universe.

This chain is only as accurate as its weakest link. Up to now, finding an accurate distance to the Large Magellanic Cloud, a satellite galaxy to the Milky Way, has proved elusive. Stars in that galaxy are used to fix the distance scale for more remote galaxies, so it is crucially important.

“For extragalactic astronomers, the distance to the Large Magellanic Cloud represents a fundamental yardstick with which the whole universe can be measured,” said Bresolin. “Obtaining an accurate value for it has been a major challenge for generations of scientists. Our team has overcome the difficulties using an exquisitely accurate method, and is already working to cut the small remaining uncertainty by half in the next few years.“

Careful observations of a rare class of double star have now allowed a team of astronomers to deduce a much more precise value for the Large Magellanic Cloud distance—163,000 light-years.

“This is a true milestone in modern astronomy. Because we know the distance to our nearest neighbor galaxy so precisely, we can now determine the rate at which the Universe is expanding—the Hubble constant—with much better accuracy,” says Kudritzki. “This will allow us to investigate the physical nature of the enigmatic dark energy, the cause of the accelerated expansion of the Universe.”

—Adapted from a UH Mānoa Institute for Astronomy news release

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Category: Research

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  1. Mr. Raymond Kenneth Petry says:

    163,000 lightyears to–What:

    The Center of Mass (total mass)?
    The Center of Number (total stars)?
    The Center of Luminance (observable)?
    The Center of Modal Bunchiness (‘arms’)?
    The Center of Magellanic-local dark matter?
    The Center of Eclipsing Binaries (eight)?
    The Center of Standard-Candle Moments?

    Is that today–or–to where it was 163,000 years ago?
    Does that account for Stellar Aberration (galaxy scale)?
    Is that accounting for 163,000 years of Hubble Expansion?

    And just technically speaking–What, is the “geometrical center” looking broadside? (It’s not in the dictionary like ‘geometric mean’ is for lengthwise from our point), And, How significant is it when taking only eight cases?

    (I mean–from the standpoint of walking away from this article with a reference number ’163,000 lightyears’?)

    So–What’s the distance to the center of our Milky Way galaxy, Or is that still less-accurate itself…?

    Ray.

    • Dear Mr. Petry,

      I understand that you have discussed some of your questions already with my colleague Dr. Fabio Bresolin in or after his class. Dr. Bresolin is co-author of this paper as I am. I suggest that you contact him directly should you have more questions.

      With kind regards

      Rolf Kudritzki

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