| Name: | Sandeep Kumar Dubey |
| Affiliation: | Physical Research Laboratory, Ahmedabad |
| Conference ID : | ASI2024_770 |
| Title : | Spectral scans of umbral flashes in chromospheric heights, a study using using MAST CaII 8542 Å narrow-band observation |
| Authors : | 1. Shibu K. Mathew
2. Sandeep Kumar Dubey |
| Authors Affiliation: | Udaipur Solar Observatory, Physical Research Laboratory, Ahmedabad, 380009, India |
| Mode of Presentation: | Poster |
| Abstract Category : | Sun, Solar System, Exoplanets, and Astrobiology |
| Abstract : | Umbral flashes are one of the most dynamic phenomena observed in the sunspot umbrae in the chromospheric heights. We analyzed the spectroscopic observations of umbral flashes in the Ca II 8452 Å line recorded by a narrow-band imager working with the Multi-Application Solar Telescope (MAST). The deduced data is analyzed to obtain various properties of the umbral flashes. An intensity enhancement up to 30% or more is observed in umbral flashes, and was also found to have a periodicity of ≈ 3 min. The bi-sector analysis of the observed profiles after the removal of the mean umbral profile revealed line-of-sight velocities in the umbral flashes, with an average value of -0.9 km/sec . We also observed horizontally propagating line-of-sight velocity disturbances in the penumbra, which might be associated with the umbral flashes, even though we could not establish a one-to-one correspondence. The visual effect of running penumbral waves could be produced by the horizontally propagating line-of-sight velocity disturbances, which in effect produces intensity fluctuations in the images when it is observed at the line-center wavelength. By looking at the simultaneous photospheric SDO/HMI observations, we did not find any similar intensity enhancements corresponding to the flashes observed in the Ca II chromospheric line. |
