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Observation by Kevin Gurney: Metallic A-type star

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Kevin Gurney


Kevin Gurney


2018 Mar 21 - 01:03


2018 Mar 23 - 18:48

  • Altair Astro 10in RC truss tube
  • Alpy 600 Spectrograph
  • Mesu 200 mount
  • Atik 460EX

12 x 120sec sub-exposures


West Sheffield

Target name

HD 93901


Metallic A-type star

About this image

HD 93901 is an Am-type star - that is, class A, but with strong metallicity (I love the way astrophysics can't count beyond 3 , and calls anything other than H or He, a 'metal' :). This is manifest in the spectrum by the increased amplitude of features between the Balmer lines. The full spectrum is given as kA4hA7mF5 (which gives relative stengths of the k -line, H, and metallicity, m).

The top panel of the figure shows the (instrument-corrected) spectrum in red, and a 'standard' A-type star for comparison (HD103478, A3V, taken on the same night). Below, are the rectified spectra (continuum removed) where I have also scaled the Am-type star to have the same amplitude  range as its standard counterpart, and shifted it up slightly to ease comparison. [Is the general increase in amplitude of the A3V star a luminance effect? I couldnt see a luminance given in the spectrum...].

I still remain astounded at how much you can see from your backyard with a low-res spectroscope... :)

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