9:45 AM - 10:15 AM
[PCG22-04] ALMA-Hinode-IRIS coordinated observations of solar nanoflares in cycle 4
Keywords:The Sun, Nanoflare, Coronal heating
The observation for this project was executed in March 19, 2017, successfully coordinated with observations by space-borne Hinode and IRIS. The ALMA antenna configuration was C40-1 with compact baseline lengths of 15-155 m, providing a beam size of 3.7 arcsec. An ephemeral active region on the solar disk, which was the only bright region because of extremely low solar activity condition, was the target and the time series of band 3 (100GHz) map data was obtained for about 3 hours in total. The verification of the co-alignment among ALMA, Hinode, and IRIS data was the first challenging step in the data analysis, but owing to efforts on verification of the solar coordination, we finally confirmed the reliable co-alignement. Microflares did not take place in the field of view during the observation, but we found a lot of smaller increases in ALMA temperature map. The largest one is in order of 30 K, which is sufficiently above the noise level (10K). It was located at the magnetic polarity inversion line where a positive magnetic polarity island is located next to a negative island. Smaller ALMA temperature increases are observed at the area beside magnetic islands, rather than inside the islands. The spatial size of temperature increase events is similar to the beam size. Assuming that the temperature increase is due to energy input to the upper chromosphere, the observed temperature increase may correspond to the energy input in order of 10^22 erg. Moreover, we also found a part of temperature increase shows periodic changes, which may suggest compressional waves. In this talk, we present an initial result from our ALMA-Hinode-IRIS observation and discuss the energy evaluation of solar nanoflares and the signature of waves.