O AND Ne IN AN H-He FAST SOLAR WIND

Journal Article · Tue Dec 20 04:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/743/2/205· OSTI ID:22004394

Byhring, H S; Esser, R ^[1]; Lie-Svendsen, O ^[2]

---

1. Department of Physics and Technology, University of Tromso, NO-9037 Tromso (Norway)
2. Norwegian Defense Research Establishment, P.O. Box 25, NO-2027 Kjeller (Norway)

We have studied the abundances and ion fractions of O and Ne in an H-He fast solar wind with emphasis on gravitational settling in the chromosphere and corona. We use a time-dependent numerical model that spans the mid- to upper chromosphere, transition region, corona, and solar wind and calculates the particle density, flow velocity, parallel and perpendicular temperature, and heat flux for all particle species simultaneously. We investigate the effect of including He on the O and Ne abundances in the solar wind for two different flux tube expansion factors and find that He has a modest effect, which nevertheless becomes important for low expansion factors. The He, O and Ne abundances in the solar wind can be modulated by varying the magnetic flux tube expansion factor, but we have not been able to reproduce the observed solar wind abundances of He, O and Ne simultaneously. Furthermore, we find that unless O is heated to temperatures higher than those observed in polar coronal holes, there will be an O abundance enhancement in the corona, at about 1.6 R{sub Sun }. Finally, we find that we can reproduce the in situ ion fractions for O and Ne in H-He background solutions with a modest He heating rate, which implies a coronal He abundance of about 20-40%.

• OSTI ID: 22004394
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 743; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
CHROMOSPHERE
HEAT FLUX
HEATING RATE
MAGNETIC FLUX
SOLAR WIND
SUN
TIME DEPENDENCE