Carrington Maps in H i Lyα and Their Relationships with Extreme-ultraviolet and Magnetic-field Maps

Abstract

H i Ly α emission in the chromosphere and transition region is a key ingredient of the incident radiation to coronal neutral hydrogen for modeling corona Ly α emission. The Ly α emission distribution across the solar disk can be obtained from a Ly α Carrington map. Before the launch of the Advanced Space-based Solar Observatory (ASO-S), such a Ly α Carrington map was derived from the Carrington map at He ii 30.4 nm and sometimes is even assumed to be uniform. We construct the first Ly α Carrington map based on full-disk Ly α images acquired by the Solar Disk Imager (SDI) on board ASO-S and present two versions: the standard one is for a CR, and the other is daily updated. For modeling Ly α intensities during eruptions, the Carrington map with incorporated flare region is produced. Furthermore, we evaluate the difference between the Ly α Carrington map derived with SDI observations and that synthesized from the 30.4 nm data based on an empirical relationship between Ly α and He ii 30.4 nm intensities, particularly extended to flare intensities that have not been investigated before. The average difference of 38% proves the importance of the Ly α Carrington map built from observations directly. However, the synthetic Ly α Carrington map can be used as an approximation before SDI data are available. The comparison between the SDI Ly α Carrington map and the corresponding magnetic field synoptic map indicates that active regions in general are brighter in Ly α , while the sunspot umbras with strong magnetic field strength are usually weaker in Ly α .

Keywords

• Solar physics
• Astronomy image processing
• Solar ultraviolet emission