Title of article :
What is 4He from H II regions? What needs to be done to better understand the systematic errors?
Author/Authors :
Gary J. Ferland، نويسنده , , Yuri Izotov، نويسنده , , Antonio Peimbert، نويسنده , , Manuel Peimbert، نويسنده , , Ryan L. Porter، نويسنده , , Evan Skillman، نويسنده , , Gary Steigman، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2009
Abstract :
Here we summarize the discussion that took place after the presentation of papers discussing measurement of abundances from emission lines in H II regions. A cosmological test using 4He is harder than those using the other light elements due to the small dynamic range over which He/H varies for cosmologically interesting parameters. A precision of much better than 1% is needed. This precision challenges both observations and theory. Several of the major uncertainties were identified and methods of improving the accuracy were described.
Keywords :
ISM: abundances , HII regions , galaxy: abundances
Journal title :
Proceedings of the International Astronomical Union
Journal title :
Proceedings of the International Astronomical Union