In August 2005 I bought a 'Star Analyser' diffraction grating from Patten Hawksley and tried some spectroscopy.

Example Spectrum	Spectral Type or Temperature Class
	O
	B. The star 59 Cygni has spectral classification B0p. It has been the subject of considerable research and apparently has a cool H Alpha emitting envelope. Most of the research is aimed at understanding the structure and cause of this envelope. My result clearly shows the H Alpha emission line.
	A. The spectra of type A stars are dominated by lines of neutral hydrogen HI. These lines reach their maximum intensity at A2. There are also some lines of ionized metals and neutral metals also increase throughout the class. The effective temperature is about 8500K. This makes the peak wavelength of 340nm beyond the range of the HX516 camera. Examples Vega A0V, Sirius A1 and Altair A7V. My spectrum of Vega clearly shows the hydrogen lines from HA to HE and possibly HZ
	F
	G
	K Neutral metals are still dominant, with iron particularly prominent. After K5 molecular bands such as TiO appear.  The effective temperature is 4000K. In my example there appear to be many indistinct lines at least one of which may be iron. Also well seen is the atmospheric oxygen band at 757 to 770nm. Other examples are Arctrurus at K2 and Aldeberan at K5
	M
	Wolf Rayet

Notes 

Spectral Classification

Stars are classified according to spectral class, then a subclass numbered from 0 to 9. A subsequent roman numeral from 1 to 5 indicates the Luminosity class. The luminosity classes are I=Super giants, II Bright giants, III Giants, IV Sub-giants and V main sequence. An additional letter is sometimes used such as e=emission, p=peculiar, m=metallic lines etc. 

Effective Temperature and the peak wavelength are related by Wien's displacement law:   T (K) = 2897768/lambda (nm) 

Balmer Series. The four most prominent lines associated with hydrogen where accurately measured around 1862 by AJ Angstrom. In 1885 Johann Jakob Balmer announced that he had found a formula that accurately predicted the observed wavelengths. The formula is 

f= R ( 1/n_f²-1/n_i² )

where he chose n_f=2 and n_i=3,4,5,6. R was given the value 3.29163x10¹⁵. 

Later in 1914 Niels Bohr explained Balmer's empirical result by a combination of classical physics and the new quantum theory. The constant R was now given by R=2*pi²m q⁴ /h³. Where h is Plancks constant, and m and q the mass and charge of the electron. The integers n_f and n_i represent the final and initial orbit numbers of an electron. Quantum theory prompted Bohr to postulate that only certain orbits with specific radii where allowed. He then used classical physics to calculate the energy associated with those orbits. The energy of a photon is given by E=hf, so when an electron decays from an orbit with a high energy, E_i, to a lower energy orbit, E_f, the photon frequency can be calculated from hf=E_i=E_f. Following this calculation through to completion gives Balmer's formula.

 My spectrum of Vega shows the first 6 lines of the Balmer series

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