Sun 2015 - ESRI:104975

WKT

GEOGCS["Sun_2015", 
	DATUM["Sun_2015", 
		SPHEROID["Sun_2015", 695700000.0, 0.0]], 
	PRIMEM["Reference_Meridian", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["Sun_2015", 
	DATUM["Sun_2015", 
		ELLIPSOID["Sun_2015", 695700000.0, 0.0]], 
	PRIMEM["Reference_Meridian", 0.0], 
	CS[ellipsoidal, 2], 
	AXIS["Longitude (lon)", east, 
		ORDER[1]], 
	AXIS["Latitude (lat)", north, 
		ORDER[2]], 
	ANGLEUNIT["Degree", 0.0174532925199433], 
	ID["Esri", "104975"]]

Data from @esri/proj-codes

{
  "wkid": 104975,
  "latestWkid": 104975,
  "macro": "PE_GCS_XT_SUN",
  "name": "Sun_2015",
  "wkt": "GEOGCS[\"Sun_2015\",DATUM[\"Sun_2015\",SPHEROID[\"Sun_2015\",695700000.0,0.0]],PRIMEM[\"Reference_Meridian\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"Sun_2015\",DATUM[\"Sun_2015\",ELLIPSOID[\"Sun_2015\",695700000.0,0.0]],PRIMEM[\"Reference_Meridian\",0.0],CS[ellipsoidal,2],AXIS[\"Longitude (lon)\",east,ORDER[1]],AXIS[\"Latitude (lat)\",north,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433],ID[\"Esri\",\"104975\"]]",
  "description": "Sun 2015",
  "authority": "Esri",
  "version": "10.7.0",
  "deprecated": "no",
  "areaname": "Body",
  "extent": {
    "slat": -90,
    "nlat": 90,
    "llon": -180,
    "rlon": 180
  }
}