On the
Tholen and
SMASS taxonomic scheme,
Boreas is classified as a common
S-type asteroid with a stony composition. It has also been characterized as a Sw-subtype. Several rotational
lightcurves gave a
rotation period between 3.4741 and 3.49 hours with a brightness variation between 0.25 and 0.35
magnitude (). In 1994, astronomer
Tom Gehrels estimated
Boreas to measure 3.5 kilometers in diameter, based on an assumed
albedo of 0.15. The
Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 3.07 kilometers with an
absolute magnitude of 14.93. == Naming ==