UPFLOWS IN THE CENTRAL DARK LANE OF SUNSPOT LIGHT BRIDGES
- Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway)
We use high spatial and spectral resolution observations obtained with the CRisp Imaging SpectroPolarimeter at the Swedish 1 m Solar Telescope to analyze the velocity profile of granular light bridges (LBs) in a sunspot. We find upflows associated with the central dark lanes of the LBs. From bisectors in the Fe I 630.15 nm line we find that the magnitude of the upflows varies with height, with the strongest upflows being deeper in the atmosphere. Typical upflow velocities measured from the 70% bisector are around 500 m s{sup -1} with peaks above 1 km s{sup -1}. The upflows in the central dark lane are surrounded by downflows of weaker magnitude, sometimes concentrated in patches with enhanced velocities reaching up to 1.1 km s{sup -1}. A small spatial offset between the upflows and the continuum dark lane is interpreted as a line-of-sight effect due to the elevated nature of the dark lane and the LB above the umbral surroundings. Our observations show that the central dark lane in granular LBs is not equivalent to the intergranular lanes of normal photospheric granulation that host convective downflows. These results support recent MHD simulations of magneto-convection in sunspot atmospheres.
- OSTI ID:
- 21451024
- Journal Information:
- Astrophysical Journal Letters, Vol. 718, Issue 2; Other Information: DOI: 10.1088/2041-8205/718/2/L78; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
Similar Records
LATERAL DOWNFLOWS IN SUNSPOT PENUMBRAL FILAMENTS AND THEIR TEMPORAL EVOLUTION
TEMPORAL EVOLUTION OF VELOCITY AND MAGNETIC FIELD IN AND AROUND UMBRAL DOTS