view Abstract Citations (6) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Spectrum of Arcturus Hacker, Sidney G. Abstract This paper summarizes with critical comments the atomic and molecular spectra I identified in Arcturus (a Bootis; Draper class Ko) in the region XX 4119-6743. The spec- trograms were taken with the 15-foot auto-collimating spectrograph at the coudé focus of the 100-inch Mount Wilson reflector. They consist of (i) a set of low dispersion plates I (exposure: 0h42m) mapping the region XX 4119-6743 with a dispersion increasing from I 2.30 A/mm at X 4120 to 13.10 A/mm at X 66oo and (2) a set of high-dispersion plates (exposure: 61~I6m) mapping the two regions XX 4245-4520 and XX 4525-4975 with a dispersion of 0.97 A/mm at X 4200 and 2.17 A/mm at X 4900. The plates were meas- I ured on a Hilger comparator and reduced by the Hartmann formula in the usual way. I Visual estimates of the intensities on an arbitrary scale were made at the time of meas- urement. I On the high-dispersion plates 397 unbiended lines gave a weighted mean of -5.36 I ± 0.03 km/sec for the radial velocity. On the low-dispersion plates 702 lines gave -6.63 ± 0.22 km/sec, and the weighted mean for the 1099 lines is -6.17 ± 0.20 km/sec. I The following twenty-eight elements have been identified on these plates as present I in Arcturus: H, Na, Mg, Al, Si, Ca, Sc, Sc+, Ti, Ti+, V, V+, Cr, Cr+, Mn, Mn+, Fe, Fe+, I Co, Ni, Cu, Zn, Sr, Sr+, V+, Zr, Zr+, Cb, Ru, Ba+, ~j+, Ce+, Nd+, Sa+, Eu+, Gd+. From the available evidence the following seem to be absent: Sit, Y, Mo, La, Yb, Lu~, HJ+, W, Ti. I The following may be present or absent (the available evidence is insufficient for definiteness): Li, Mg+, Ni+, Ga, Ge, Mo+, J~, Ba, Pr+, Tb+, Dy+, Ho+, vb+. I The following ten are not available on these plates: K, C&, Cot, Rb, Rh, Pd, Ag, Cd, Er~, Pb. Ca~ has very strong lines beyond the violet limit of the plates. I Five molecular spectra have been found to be present on these plates: CH, CN, C2 SiF, BO. There may possibly be a trace of A10 and TiO; but the evidence, which is discussed, is found to be far from definite. CaH, MgH, and ZrO are absent. Of the 350 or so unbiended lines otherwise unidentified, about 100 coincide, within I the errors of measurement, with lines noted as band lines in the sun-spot spectrum. I More than 200 unidentified solar lines seem to be present in Arcturus; and those which are strengthened in the spot spectrum relative to the disk are, in general, stronger in I Arcturus. Throughout the stellar spectrum the relative intensities of the arc lines are strikingly I similar to those in the sun-spot spectrum, but the enhanced lines are stronger. Altogether, about 3000 lines have been identified. Approximately 30 unblended lines I of moderate strength remain unidentified Publication: The Astrophysical Journal Pub Date: March 1936 DOI: 10.1086/143709 Bibcode: 1936ApJ....83..140H full text sources ADS |