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A Spectral Classification Syntax for Binaries

  1. Apr 6, 2017 #1
    for α Cnc one gets from


    a spectral type of

    I don't get behind this special use of "/" - Syntax - what's that that meant to denote?

    kA7Vm+F02III xor kA7Vm+F02IVSr?
    Anything else?
    Last edited: Apr 6, 2017
  2. jcsd
  3. Apr 7, 2017 #2
    I think the / is intended to separate the spectral class of the components but this one looks strange. If you look up the star here http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=B/mk you will see a range of classifications.
    You can follow the links to the papers the last reference has it as Am (A5/A9/F0) in the body of the paper.
    I tried to follow the link to your clasification but you had to pay for access.
    Regards Andrew
  4. Apr 7, 2017 #3
    Yes, of course. It's generally used both for separating alternative subclasses and luminosities - "alternative" here as opposed to "between" (that would be "-").

    Here however it's unclear, especially because the "A" and" "F" classification are given en suite without such any seperator.

    But talking about it - maybe the tail means

    one of (F0III, F2III, F0IVSr, F2IVSr)


    What however combining "A" and "F" without a separator shall denote ... well...

  5. Apr 7, 2017 #4
    I think your only option is to look up the reference if you want to clarify the meaning.
    Regards Andrew
  6. Apr 7, 2017 #5
    Yep, So more precisely, I think the only option for me is to an accessible version of the doc ...

    And indeed! There indeed is one:

    [RA91] Rao, S. S. & Abhyankar, K. MK morphological study of Am stars at 66 Å/mm. Journal of Astrophysics and Astronomy, Springer, 1991, 12, 133-178. doi: http://citeseerx.ist.psu.edu/viewdoc/download?doi=

    So by [RA91] Table. 3, Simbad's encoding

    "kA7VmF0/2III/IVSr" means:

    K line: A7 V
    m (i.e m 39) line: F0 III
    m (i.e. m 43) line: F2 III/IV

    and Sr line present.

    So the "/" operator binds and only binds to the rightmost class ("F") or subclass ("0", "2") token to its left.

    And it's nothing about "Binaries".
    Last edited: Apr 7, 2017
  7. Apr 16, 2017 #6

    stefan r

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    kA7VmF0/2III/IV Sr

    I am not an astronomer. Would like a better answer.

    k Spectra with interstellar absorption features
    A7 Main sequence star spectral class A7
    V luminosity class five

    m Enhanced metal feature
    F0/2 spectral classes F0 and F2
    III/IV luminosity class III/IV
    Sr Strontium

    This could mean the strontium emission line has a signal strength equivalent to a star with luminosity class III/IV. Emission line spectra contain more than one peak so you could measure more than one spectral class. Would look purple than an A7 should look.
  8. Apr 17, 2017 #7
    Then I would propose you read the paper Solkar gave the link to.

    Regards Andrew
  9. Apr 17, 2017 #8

    stefan r

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    Gold Member

    I did that before commenting.
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