High Resolution Observations of Chromospheric Jets in Sunspot Umbra

Abstract

Recent observations of sunspot's umbra suggested that it may be finely structured at a sub-arcsecond scale representing a mix of hot and cool plasma elements. In this study we report the first detailed observations of the umbral spikes, which are cool jet-like structures seen in the chromosphere of an umbra. The spikes are cone-shaped features with a typical height of 0.5-1.0 Mm and a width of about 0.1 Mm. Their life time ranges from 2 to 3 min and they tend to re-appear at the same location. The spikes are not associated with photospheric umbral dots and they rather tend to occur above darkest parts of the umbra, where magnetic fields are strongest. The spikes exhibit up and down oscillatory motions and their spectral evolution suggests that they might be driven by upward propagating shocks generated by photospheric oscillations. It is worth noting that triggering of the running penumbral waves seems to occur during the interval when the spikes reach their maximum height.

References in corpus (17)

• The formation of the Halpha line in the solar chromosphere
• Dynamic Fibrils are driven by Magnetoacoustic Shocks
• Magneto-convection in a sunspot umbra
• Physical Properties of a Sunspot Chromosphere with Umbral Flashes
• Subsurface magnetic field and flow structure of simulated sunspots
• Wave Propagation and Jet Formation in the Chromosphere
• Short dynamic fibrils in sunspot chromospheres
• Precursor of Sunspot Penumbral Formation discovered with Hinode SOT Observations
• Direct Imaging of Fine Structure in the Chromosphere of a Sunspot Umbra
• Characteristic Dependence of Umbral Dots on their Magnetic Structure
• Temporal Evolution of Velocity and Magnetic Field in and around Umbral Dots
• Evidence for Fine Structure in the Chromospheric Umbral Oscillation
• Spectroscopic measurements of dynamic fibrils in the Ca {\small{II}} 8662 Å line
• Fine structures in the atmosphere above a sunspot umbra
• Properties of Umbral Dots as Measured from the New Solar Telescope Data and MHD Simulations
• Properties of Umbral Dots from Stray Light Corrected Hinode Filtergrams
• Can overturning motions in penumbral filaments be detected?

Cited by in corpus (21)

• Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
• Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST)
• The European Solar Telescope
• Frequently Occurring Reconnection Jets from Sunspot Light Bridges
• Inference of the chromospheric magnetic field orientation in the Ca II 8542 A line fibrils
• On the Active Region Bright Grains Observed in the Transition Region Imaging Channels of IRIS
• A Hot Downflowing Model Atmosphere For Umbral Flashes And The Physical Properties Of Their Dark Fibrils
• Dynamics in Sunspot Umbra as Seen in New Solar Telescope and Interface Region Imaging Spectrograph Data
• Chromospheric Plasma Ejections in a Light Bridge of a Sunspot
• Umbral chromospheric fine structure and umbral flashes modelled as one: the corrugated umbra
• The formation of small-scale umbral brightenings in sunspot atmospheres
• The Propagation of Coherent Waves Across Multiple Solar Magnetic Pores
• On Modeling the Kelvin--Helmholtz Instability in Solar Atmosphere
• Stable Umbral Chromospheric Structures
• Alfvénic motions arising from asymmetric acoustic wave drivers in solar magnetic structures
• Downflowing umbral flashes as an evidence of standing waves in sunspot umbrae
• Spatial Distribution of Origin of Umbral Waves in a Sunspot Umbra
• First Observation of Chromospheric Waves in a Sunspot by DKIST/ViSP: The Anatomy of an Umbral Flash
• Fine wave dynamics in umbral flash sources
• The dynamics of 3-minute wavefronts and their relation to sunspot magnetic fields
• Behaviour of oscillations in loop structures above active regions