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Thread: Stellar age translation

  1. #1
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    Stellar age translation

    Confused of York writes:
    I want to know the age of a particular star, which seems to be given in a reference I've found; but I don't understand the units.
    The star is HD 155902, the reference is
    https://books.google.co.uk/books?id=...%20age&f=false

    and the figure for the system's age is 9.27 +/- 0.30 (log Myr^-1). What is that in good old vanilla years?

  2. #2
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    Link not working for me

  3. #3
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    Quote Originally Posted by eburacum45 View Post
    Confused of York writes:
    I want to know the age of a particular star, which seems to be given in a reference I've found; but I don't understand the units.
    The star is HD 155902, the reference is
    https://books.google.co.uk/books?id=...%20age&f=false

    and the figure for the system's age is 9.27 +/- 0.30 (log Myr^-1). What is that in good old vanilla years?
    Hmmm. link didn't work for me either. Maybe this will work: Link to page 159 of "Brown Dwarf Companions..."

    Concerning the actual question, it would help to know the method of age determination being referenced by the book/paper in question.
    See for example: (2013) Chromospheric Activity as an Age Indicator
    Forming opinions as we speak

  4. #4
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    Quote Originally Posted by antoniseb View Post
    Hmmm. link didn't work for me either. Maybe this will work: Link to page 159 of "Brown Dwarf Companions..."
    That looks like a nice book. Pages 18 - 22 address methodology for age determination.
    We know time flies, we just can't see its wings.

  5. #5
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    That's the right book, but the data I want to decode is on page 32.
    Here's a snapshot. The star I want to discuss is right at the top.
    Attached Images Attached Images

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    Not seeing that either...
    Forming opinions as we speak

  7. #7
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    I'd guess that this was the log of 1/age in megayears - which would make it 1.28Myr. But that is really young.

    Have you tried http://exoplanets.astro.yale.edu/sci...spocs_evol.php ? That has the age of the star as 12Gy, which seems more feasible. Also has high/low estimates on it.

  8. #8
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    That looks to me as if 9.27 ought to be the logarithm (base 10) of the age in years. So, the age would be

    age = 10^(9.27) = 1.86 billion years

    However, this guess doesn't agree with the "Myr^-1" part of the quoted value.

  9. #9
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    Once again, a publication aimed at colleagues is using some dubious notation the rest of us don't recognize.

  10. #10
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    The book is about brown dwarf companions of young Sunlike stars, so I'd guess that the 1.86 Gyr figure is correct. Thanks!

  11. #11
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    My money says it's simply a typo that didn't intend the mysterious Myr^-1. So I agree with StupendousMan, it should just be log yr. Sometimes it's not that people are using mysterious units only their colleagues know, it is that they are using conventions their colleagues know so well that they don't bother to check their axis labels!

  12. #12
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    Did you all hear that broom sound , the actual age just flew right over my head

  13. #13
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    Well, the Sun is about 4.6 billion years old, and this star is only 1.86 billion years old, so it is significantly younger. I was hoping it would be a bit older than that, but no such luck.

    The 'Gyr' term is a quick way of saying 'a billion years'; it is short for 'gigayears'.

  14. 2020-Jan-22, 03:23 AM

  15. #14
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    So that’s what gyr means

  16. #15
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    Quote Originally Posted by Sinbad View Post
    So that’s what gyr means
    1 gyr = 1 billion years (one gigayear)
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