A Tale of two Stars

[robin_astro]

To answer a question raised in another post about the possibility of using the Star Analyser to do spectral classification, here is an example of a couple of stars I attempted to classify using spectra  at the same resolution as a typical Star Analyser spectrum (~45A).  It is rather long so I have put it in a pdf but the executive summary is

"Spectral classification is based on what spectral lines are present and at what strength, not the shape of the spectrum continuum and this needs sufficient resolution to resolve these lines (Typically 10A or better). Spectra at typical Star Analyser resolution can contain clues as to the approximate spectral type but in general they are not good enoigh for precise spectral classification. The discovery in the early 20th century that the lines in the spectrum could be used to measure the temperature of a star and its size revolutionised stellar astrophysics"

Cheers

Robin

A Tale of Two Stars.pdf

[robin_astro]

I can now reveal Star B is 2MASS J19095965+0437597,  a previously unknown variable, co-discovered with Adam Nowak

https://www.aavso.org/vsx/index.php?view=detail.top&oid=1498835

Note the brightness of this star at ~mag 19 g  which would make it by far the faintest object recorded spectroscopically using amateur equipment.  This is a bit of a cheat though as my spectrum mainly covers the R and I bands where the star is significantly  brighter (This is an M6 star, further reddened significantly by the interstellar medium, which explains its presence in the 2MASS catalogue of objects detectable in the IR at 2 microns. 

Cheers

Robin