Primordial 4He abundance: a determination based on the largest sample of H II regions with a methodology tested on model H II regions

Free Access

Table 1

Input parameters for the grid of the photoionised H ii region models.

Parameter	Value

log Q(H)^a	52, 53, 54
Starburst age, Myr	1.0, 2.0, 3.5, 4.0
N _e ^b	10, 10², 10³, var
log f^c	−0.5, −1.0, −1.5, −2.0
Oxygen abundance 12+log O/H	7.3, 7.6, 8.0, 8.3
⁴He mass fraction Y	0.254

Notes.

^(a)

Log of the number of ionising photons in units s^-1.

^(b)

The electron number density in units cm^-3. The electron number density in models labelled “var” is varied along the radius according to Eq. (1).

^(c)

Log of volume-filling factor.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.