Astronomy and Astrophysics – Astronomy
Scientific paper
Mar 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993apj...405..803c&link_type=abstract
Astrophysical Journal v.405, p.803
Astronomy and Astrophysics
Astronomy
Errata, Addenda
Scientific paper
In the paper "On Determining the primordial Helium Abundance from the Spectra of H II Galaxies" by Alison Campbell (ApJ,401,157(1992]) a correction should be made to one of the values given for (He/HN)_p_. The value (He/N)_p_ = 0.0738 +/- 0.0016 which was quoted from the work of B. E. J. Pagel, E. A. Simonson, R. J. Terlevich, & M. Edmunds (MNRAS 255,325(1992]) is their standard least-squares fit to the 19 object O/H-He/H data set (Table 16). They prefer a value (He/N)_p_ = 0.0738+/-0.0021, based on the average of O/H-He/H and N/H-He/HN regressions and obtained by a maximum-likelihood technique which B. Pagel (private communication) has informed the author correctly accounts for errors in both y and x. This value for (He/N)_p_ is 2.0 σ, rather than 2.7 σ, below the theoretical lower limit of 0.078+/-0.0004. (The uncertainty in the theoretical (He/H)_p_ reflects the 1 σ experimental uncertainty in the neutron lifetime; T. P. Walker, G. Steigman, D. N. Schramm, K. A. Olive, & H. Kang, ApJ, 376, 5I (1991), and references therein.] Further, the ~2% overestimate of the true value of (He/H)_p_ which arises from the neglect of x uncertainties (Sections III and VI of the author's paper) does not apply to Pagel et al.'s result. The presence of an intrinsic dispersion in helium abundance at a given oxygen abundance was noted by B. E. J. Pagel, R. J. Terlevich, & J. Melnick (PASP, 98,1005(1986]) and was associated by them with winds from WolfRayet (WR) stars. Pagel et al. (1992) exclude from their regression analysis all H II galaxies exhibiting WR emission features and find that the remaining objects in their sample show no physical scatter.
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