[{"_id":1,"last_name":"Bernard","first_name":"Emil","year_born":1868,"year_died":1941,"nationality":"France"},{"_id":2,"last_name":"Rippl-Ronai","first_name":"Joszef","year_born":1861,"year_died":1927,"nationality":"Hungary"}]

db.collection.aggregate([{$bucket:{groupBy:"$year_born",/** Field to group by*/boundaries:[1840,1850,1860,1870,1880],/** Boundaries for the buckets*/default:"Other",/** Bucket ID for documents which do not fall into a bucket*/output:{/** Output for each bucket*/"count":{$sum:1},"artists":{$push:{"name":{$concat:["$first_name"," ","$last_name"]},"year_born":"$year_born"}}}}},{$addFields:{upperBound:{"$arrayElemAt":[[1840,1850,1860,1870,1880],{$sum:[{"$indexOfArray":[[1840,1850,1860,1870,1880],"$_id"]},1]}]}}}])