Teegarden's Star is an M-type red dwarf star located about 12 light years away in the constellation Aries.
main sequence stars
Barnard's star is a red dwarf, M-type main sequence star.
Barnard's Star is a red dwarf star
A delta star is a mathematical technique to simplify the analysis of an electrical network, not a "real" star.A delta star is not a its a mathematical formula see related link