On the generation of umbral flashes and running penumbral waves
From a review of the observed properties of umbral flashes and running penumbral waves it is proposed that the source of these periodic phenomena is the oscillatory convection which Danielson and Savage (1968) and Savage (1969) ave shown is likely to occur in the superadiabatic subphotospheric layers of sunspot umbras. Periods and growth rates are computed for oscillatory modes arising in a simple two-layer model umbra. Finally, the results suggest that umbral flashes result from disturbances produced by oscillatory convection occurring in the upper subphotospheric layer of the umbra where the superadiabatic temperature gradient is much enhanced over that in lower layers, while running penumbral waves are due to oscillations in a layer just below this upper layer.
- Research Organization:
- Hale Observatories, Pasadena, CA
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-001211
- OSTI ID:
- 4416507
- Journal Information:
- Solar Physics, Journal Name: Solar Physics Journal Issue: 2 Vol. 30; ISSN 0038-0938
- Publisher:
- Springer
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
Solar Records: The Wolf Sunspot Index and Umbral/Penumbral Ratio
Observations of oppositely directed umbral wavefronts rotating in sunspots obtained from the new solar telescope of BBSO
The influence of the magnetic field on running penumbral waves in the solar chromosphere
Dataset
·
Sun Dec 31 23:00:00 EST 2017
·
OSTI ID:1389514
Observations of oppositely directed umbral wavefronts rotating in sunspots obtained from the new solar telescope of BBSO
Journal Article
·
Sun Jan 31 23:00:00 EST 2016
· Astrophysical Journal
·
OSTI ID:22887105
The influence of the magnetic field on running penumbral waves in the solar chromosphere
Journal Article
·
Thu Dec 19 23:00:00 EST 2013
· Astrophysical Journal
·
OSTI ID:22348445