ON MOLECULAR HYDROGEN FORMATION AND THE MAGNETOHYDROSTATIC EQUILIBRIUM OF SUNSPOTS
- Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
- National Solar Observatory, Sacramento Peak, P.O. Box 62, Sunspot, NM 88349 (United States)
We have investigated the problem of sunspot magnetohydrostatic equilibrium with comprehensive IR sunspot magnetic field survey observations of the highly sensitive Fe I lines at 15650 A and nearby OH lines. We have found that some sunspots show isothermal increases in umbral magnetic field strength which cannot be explained by the simplified sunspot model with a single-component ideal gas atmosphere assumed in previous investigations. Large sunspots universally display nonlinear increases in magnetic pressure over temperature, while small sunspots and pores display linear behavior. The formation of molecules provides a mechanism for isothermal concentration of the umbral magnetic field, and we propose that this may explain the observed rapid increase in umbral magnetic field strength relative to temperature. Existing multi-component sunspot atmospheric models predict that a significant amount of molecular hydrogen (H{sub 2}) exists in the sunspot umbra. The formation of H{sub 2} can significantly alter the thermodynamic properties of the sunspot atmosphere and may play a significant role in sunspot evolution. In addition to the survey observations, we have performed detailed chemical equilibrium calculations with full consideration of radiative transfer effects to establish OH as a proxy for H{sub 2}, and demonstrate that a significant population of H{sub 2} exists in the coolest regions of large sunspots.
- OSTI ID:
- 22011903
- Journal Information:
- Astrophysical Journal, Vol. 745, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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