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7/29/2015

Perfect Time of the Year to Observe "Methuselah star" or HD 140283 / HIP 76976


     Last September, Phil Pliat over at the Bad Astronomer had a good article on the newest oldest star to be given the oldest title or "The Methuselah Star."  Here is a LINK to his incredible explanation of the star, far better then the wack job I am going to put together here.  I will provide several links so you can learn more about this star.

      This truly isn't anything new, James Kaler in his book, Extreme Stars at the Edge of Creation covers this star on page 208 of his book. The book originally came out in the year 2001, reprinted in 2002 and the first paperback edition was released in 2010.  So this star has been known about for around the last 14 to 15 years if not longer. A paper LINK was released about it though I believe in 2014. For a really in depth explanation of the star and why it is so old, please read Phil Pliat's article above. To summarize Dr. Kaler he simply explains that this is a binocular object, so binoculars and telescopes can easily capture it.  Dr. Kaler also explains that the iron content of this star is less than most globular clusters which are naturally metal poor (metal poor being elements higher than helium). Most globular clusters are very old, so old that most if not all O B stars are no longer seen there. In addition, the metal content of those stars in globular clusters are not as enriched in heavy metals as are stars that formed later in the disk of the galaxy. We know the globular clusters are also old because the exist in the halo of the galaxy, and that the halo was formed before the disks were formed.  We know that based on the spectra of the stars in those locations and the degrees of metals heavier than helium found there, which is metal and iron poor since those metal poor stars in the globular clusters. Stars in the disk of the galaxy have far more metals in them above helium than those in the halo of the galaxy.

      HD 140283 thus is poor in metals and iron, making it via spectra one of the oldest stars known. How old? The universe is 13.82 billion years and the age of HD140283 is estimated to be 14.3 by (older than the universe so not right) but with a +/-.8 by.  So best guess is that HD 140283 is about 13.5 billion years old. Dr. James Kaler to quote him states "When you look at the darkened sky, you are looking at one of the oldest single stars in the Galaxy and are looking back to a time shortly after the Galaxy began!" It is also cool as Phil Pliat points out that we are capable of understanding the galaxy and universe around us via science.  So if sometime in the next month you are out in the backyard, or at a dark site, point your scope for a minute to Libra and go to HD 140283 and look at the star and contemplate how old it is. 13.5 billion years, the beginning of our galaxy! That is indeed worthy of a few minutes of your time to look at this object in my opinion! I'll be doing it.

Here are some additional links for this object and a finder chart for it that I created. The hop starts with Beta Libra or Zubeneschamali and you can follow the arrows to HD 140283. The linkes and chart should make this an interesting object to take a look at if you haven't already. Good hunting!

Sky-Map.org Info and Star Chart

NASA March 7th, 2013 Article 

Space.com March 7th Article 

January 10th, 2013 Nature Article (Great Piece!)









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