CLASSIFICATION
Nine stars were reclassified. This is due to the change in the resolution of the survey. All of the stars of this study (with the exception of BD +06 0648) were taken from the Henry Draper Catalogue. The HD survey used a 2 Å resolution, whilst the Coude Feed has a resolution of 1 Å. The higher resolution allows for a more specific and detailed look as to the spectral and luminosity classification of the stars.
The following are explanations of the classification (or subsequent reclassification) of the stars based on spectral analysis.
HD 74462
The first stars did leave remnants behind. There were high abundances of carbon and oxygen in the universe for stars to form. Some of these stars formed are now considered “Carbon Stars”. This is one such star. It is an R carbon star. It can’t be an N carbon star because it doesn’t break up the spectrum. It has high abundances of carbon with central depths that exceed the solar model. It also has low Iron. These stars are becoming prevalent. It is also in the correct temperature range. It also has a high amount of hydrogen in its spectrum. Its classification of G5IV corresponds with the carbon classification of C0.
HD 15596
The depth of the Balmer series corresponds with the depth of a G8III star. Also, the relative depth of Sr 4215 and and Ca I 4226 ally the star with the G8 spectral type. The CH band also plays a role in its classification, with the depth and breadth of the lines.
HD 218857
This is classified as having wide lines, and it is apparent from its spectrum. It retains strong Balmer lines, whilst the H and K lines reach towards their peak. It is a delicate balance between iron and hydrogen. This star is in the middle, leaning towards the higher metallicity with a classification of G6w.
HD 235397
The H and K lines rise to prominence in this star, becoming one of the easily detected spectral features. Hydrogen is still present, but in waning amounts. This star also has a strong ultraviolet region of its spectrum. The width of its lines indicates that it is not a giant and rather a G5V.
HD 8724
This star has strong H and K lines and strong Balmer lines. The G- band is visible and it highlights the spectrum. The width of the lines indicate that it cannot be a dwarf and is most likely not a subgiant. This star can be classified as a G5III.
HD 37634
The star has broadening spectral features. This star required only luminosity classification (from simply a G5 star to a G5 dwarf). It is classified as a dwarf due to the strengths of 4045 Fe I, H 4340.
HD 216143
The relative strength of the H and K lines show that the star cannot be earlier than a G3, because the lines are narrow and sharp, indicating giant status. Also the star has strong Balmer lines, indicating that it’s an “early” star, placing its classification at G3III
BD +06 0648
This G0III star has very strong H-Balmer lines. The prominent H and K lines also indicate that it is closer to A than K. It has narrow lines as well, placing it in the category of “giant”
HD 191615
This star has incredibly strong iron as compared to its hydrogen. This abundance of iron indicates that it is a very late G star, or possibly a K star. However, the strength of its ultraviolet region indicates that it fits better as a late G. Its line width is also narrow, although it can be said that it is not as narrow as that of a giant star. It was not reclassified and fits with its original classification of G8IV.
HD 196658
Given the central depth of the iron lines as compared with the hydrogen lines, this star is a K star. The strength of the Ca H and K lines is large. H and K reach their peak at K0. This star is not far from K0 due to the strength of these lines. The ultraviolet section of its spectrum is diminished as to indicate that the star is later than its original classification of K0. Using the Yerkes system, this star fits into the category of K1V, with its lines being wider than that of a giant or subgiant.
HD 251383
The disparity between the Hydrogen Balmer series and the iron lines in this star are even more exaggerated than in the two previous stars. This star is also past the K0 Ca H and K peak, with the two strong lines losing depth in comparison to earlier K stars. The width of these lines, especially those near the red end of the spectrum (those lines which attenuate) indicate that this star is also a dwarf. The size of the ultraviolet section of the spectrum is also diminished in comparison to earlier stars. Its classification as K2V is apt.
HD 219953
This star is a balance between the two previous (HD 196658 and HD 251383). The H and K lines are very strong, but not at their peak and the discrepancy between iron and hydr0gen series is more than evident. The ultraviolet section is diminished in comparison with later stars; however, it is increased in comparison with HD 196658. This star falls between the classification of K1V (dwarf due to its width) and K2V. K1.5V may seem appropriate; however, it is rarely used. It is more closely categorized with K1V, due to the central depth of the Ca H and K lines.
HD 204894
The Ca H and K lines are wide and weakening. It shows the signs of a mid to late K star due to the diminished violet section. A case could be made for K7 status based on the H and K lines; however, its hydrogen abundance is still too large to be considered that late of a K. Also, the TiO feature is also relatively weak. Its lines are also much narrower than that of a dwarf star. This star is best classified as a K4III.
HD 204587
The Ca H and K lines are barely recognizable in comparison with earlier K stars. This star also has an incredibly diminished ultraviolet section. The TiO and MgH features are also much more prominent than in the earlier stars, including the ones in this survey. The hydrogen lines are also weaker in comparison and the Ca I 4226 line becomes a very prominent feature. The lines are broader in this star and indicate it is a dwarf. This star is best classified as a K7V.
HD 191570
The star has strong Ca H and K lines which are stronger than the Balmer series. This places the star at later than spectral class A. The width of the lines indicates that it is not a giant, yet not a dwarf, placing it at a subgiant. The appearance of the CH band, albeit weak, makes it a F5 star. This star is best classified as F5IV.
HD 285246
This star has prevalent C and K lines as well as very strong Balmer lines. The balance between the two indicates an A5 star. The width of the lines indicates that it is a giant star placing it as an A5III.
HD 28663
The Balmer lines weaken in this star as compared with A stars. It is an early F star. There is a great disparity between the Ca H and K lines and the hydrogen lines. The width of these lines places it in the subgiant category. This star is a F2IV.
HD 48236
This star also has a balance between the Ca H and K lines and the Balmer series, however the strength of the Balmer lines indicate that it is of the A spectral class. It is a late A star and a subgiant at A5IV.