Polaris

 Polaris

I chose Polaris because it is famously known as the North Star and is easily identified for not staying relatively still in the night sky.
Chemicals: mainly Nitrogen
Location: RA 2° 31' 49" | Dec 89° 15.846'
Stellar Classification: yellow supergiant star, F7

Polaris (α Ursae Minoris, α UMi, commonly the North Star or Pole Star) is the brightest star in the constellation Ursa Minor, and the 50th brightest star in the night sky. It is very close to the north celestial pole, making it the current northern pole star and is located at RA 2° 31' 49" | Dec 89° 15.846'.

Polaris is not a single star, but a multiple star system. The main component, Alpha Ursae Minoris Aa, is an evolved yellow supergiant star belonging to the spectral class F7. It is 2,500 times more luminous than the Sun, 4.5 times more massive, and has a radius 46 times that of the Sun. The star is classified as a Cepheid variable, showing pulsations over a period of about four days.


From high signal-to-noise coude Reticon spectral obtained at Lick Observatory, the chemical composition of the bright Population I Cepheid Polaris (Alpha UMi) has been determined. The chemical abundances in Polaris are found to be completely typical of normal F-G supergiants. The iron abundance is solar (Fe/H = 0.0), and other metals are present in essentially solar ratios. Carbon is deficient (C/H = -0.4) and nitrogen overabundant (N/H = +0.4) relative to solar abundances, indicating the presence of CN-cycle products at the surface. Oxygen shows an underabundance (O/H = -0.2) that is also typical of F-G supergiants, but is not as easily understood.

Sources:
Wikipedia, the free encyclopedia. (2015, September 23). Polaris. Retrieved September 27, 2015, from https://en.wikipedia.org/wiki/Polaris

E., L. R., & E., B. H. (1986, April). The chemical composition of Polaris. Retrieved September 27, 2015, from http://adsabs.harvard.edu/abs/1986PASP...98..442L

Admin. (2014, July 28). Polaris: The North Star. Retrieved September 27, 2015, from http://www.constellation-guide.com/polaris-the-north-star/

 Visible Spectra of the Elements. (n.d.). Retrieved September 28, 2015, from http://www.umop.net/spctelem.htm