Title: Absorption-Line Intensities in B-Type Stars
Abstract: view Abstract Citations (41) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Absorption-Line Intensities in B-Type Stars Williams, E. G. Abstract Tables of equivalent widths are given for all measurable lines on photometer trac- ings of i 14 spectra of 84 B- and 0-type stars. In addition, line depths are tabulated for H and He. The interval investigated is A 4922 to X 3820. Balmer lines below X 3820 I have been measured when their wings do not overlap. I Systematic total intensity differences between spectra obtained on four different scales are appreciable oniy for the weakest lines recorded with the camera of smallest I dispersion (65 A/mm). Investigation of the instrumental effect on line depth shows that I with the dispersion of 39 A/mm at Hy the true line depth for hydrogen in no case I exceeds the observed by more than 15 per cent. In most stars the instrumental filling is probably much less. I The probable error increases with decreasing total absorption; for the hydrogen I lines Thy to H~ it is 5.7 per cent. The average percentage deviation from 67 published I hydrogen intensities is 19 per cent, but for nine stars, each measured by three other I observers, the deviations from their means are only 7.3 arithmetic and 1.7 algebraic. The contours for both hydrogen and helium lines are exponential in form, although I in n stars the lines are blunt at the center. The total intensities of the Balmer lines Hy to HO, expressed in equivalent ang- I stroms, coincide within the limits of observational error. For unbiended lines farther I down the series, the intensity drops rapidly. Published results for Ha are collected. H13, and probably Ha, are stronger than succeeding lines in the hottest stars; while in those with strong H lines (dwarfs) of later subtypes and in those of class A, Ha has decidedly low intensities. I These results are compared with recent theoretical work on Stark effect by Panne- I koek and Verwey. The relative intensities, Ha to Ho, agree well with prediction. Quantitative intensity agreement exists for the normal A stars, but calculated line widths in early B types and in A giants are too great. The theoretical contours, though I closely exponential in form, have nearly black centers; and the explanation of the observed high central intensities remains the outstanding problem. Publication: The Astrophysical Journal Pub Date: May 1936 DOI: 10.1086/143728 Bibcode: 1936ApJ....83..279W full text sources ADS | data products SIMBAD (2) Related Materials (1) Reprint: 1936CMWCI.540....1W