Physical properties of a fan-shaped jet backlit by an X9.3 flare

Abstract

Fan-shaped jets can be observed above light bridges and are driven by reconnection of the vertical umbral field with the more horizontal field above the light bridges. Because these jets are not fully opaque in chromospheric lines, one cannot study their spectra without the highly complex considerations of radiative transfer in spectral lines from the atmosphere behind the fan. We get around this by taking advantage of a unique set of observations of the H$\alpha$ line along with the Ca II 8542 and Ca II K lines obtained with the Swedish 1-m Solar Telescope where a fan-shaped jet was backlit by an X9.3 flare. The H$\alpha$ flare ribbon emission profiles from behind the fan are highly broadened and flattened, allowing us to investigate the fan as if it were backlit by continuous emission. Using this model we derived the opacity and velocity of the material in the jet and what we believe to be the first observationally derived estimate of the mass and density of material in a fan-shaped jet. Using inversions of Ca II 8542 emission via STiC, we were also able to estimate the temperature in the jet. Finally, we use the masses and POS and LOS velocities as functions of time to investigate the downward supply of energy and momentum to the photosphere in the collapse of this jet, and evaluate it as a potential driver for a sunquake beneath. We found that the physical properties of the fan material are reasonably chromospheric in nature, with a temperature of 7050 $\pm$ 250 K and a mean density of 2 $\pm$ 0.3 $\times$ 10${}^{-11}$ g cm${}^{-3}$. The total mass observed in $\mathrm{H}\alpha$ was found to be 3.9 $\pm$ 0.7 $\times$ 10${}^{13}$g and the kinetic energy delivered to the base of the fan in its collapse was nearly two orders of magnitude below typical sunquake energies. We therefore rule out this jet as the sunquake driver, but cannot completely rule out larger fan jets as potential drivers.

Accepted in A&A

References in corpus (14)

• CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
• CRISPRED: A data pipeline for the CRISP imaging spectropolarimeter
• Non-LTE inversions of the Mg II h&k and UV triplet lines
• Simulations of solar filament fine structures and their counterstreaming flows
• Detection of opposite polarities in a sunspot light bridge: evidence of low-altitude magnetic reconnection
• Small-scale chromospheric jets above a sunspot light bridge
• Explosive events associated with a surge
• Diagnostic potential of the Ca II 8542A line for solar filaments
• H$\alpha$ and H$\beta$ emission in a C3.3 solar flare: comparison between observations and simulations
• Estimating the temperature and density of a spicule from 100 GHz data obtained with ALMA
• The chromosphere above a $\delta$-sunspot in the presence of fan-shaped jets
• Solar surges related to UV bursts: Characterization through k-means, inversions and density diagnostics
• Diagnostic of Homologous Solar Surge Plasma as observed by IRIS and SDO
• Homologous flaring activity over a sunspot light bridge in an emerging active region

Cited by in corpus (6)

• A comparative study of two X2.2 and X9.3 solar flares observed with HARPS-N: Reconciling Sun-as-a-star spectroscopy and high-spatial resolution solar observations in the context of the solar-stellar connection
• Center-to-limb variation of spectral lines and continua observed with SST/CRISP and SST/CHROMIS
• Spectral variations within solar flare ribbons
• COCOPLOT: COlor COllapsed PLOTting software : Using color to view 3D data as a 2D image
• Solar flare ribbons structured by uncombed chromospheric loops
• Specialist Discussion Meeting: 3D structure of the flare chromosphere