Temperature Bias and the Primordial Helium Abundance Determination

Details Temperature Bias and the Primordial Helium Abundance Determination Temperature Bias and the Primordial Helium Abundance Determination

2001-07-10

arxiv.org/abs/astro-ph/0107189v2

Astronomy and Astrophysics

Astrophysics

28 pages + 4 figures. Revised version, accepted for publication in The Astrophysical Journal

Scientific paper

10.1086/324601

We study the effect that the temperature structure has on the determination of the primordial helium abundance, Yp. We provide an equation linking T(OIII), the temperature derived from the [OIII] lines, and T(HeII), the temperature of the He I lines, both for HII regions with O++ only and for HII regions where a fraction of O+ is present. By means of T(HeII), which is always smaller than T(OIII), we derive the helium abundances of 5 objects with low and very low metallicity (NGC 346, NGC 2363, Haro29, SBS 0335-052, and I Zw 18); these objects were selected from the literature because they include the 3 low metallicity objects with the best line determinations and the 2 objects with the lowest metallicity. From these abundances we obtain that Yp(nHc)=0.2356+-0.0020, a value 0.0088 lower than that derived by using T(OIII). We call this determination Yp(nHc) because the collisional contribution to the Balmer line intensities has not been taken into account. All the recent Yp determinations in the literature have not taken into account the collisional contribution to the Balmer line intensities. By considering the collisional contribution to the Balmer line intensities of these five objects we derive that Yp(+Hc)=0.2384+-0.0025.

Affiliated with

Also associated with

No associations

Rating

Temperature Bias and the Primordial Helium Abundance Determination does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Temperature Bias and the Primordial Helium Abundance Determination, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temperature Bias and the Primordial Helium Abundance Determination will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-537409