Small grouping of (typically 100 or less) stars, spanning up to a few tens of parsecs across, usually rich in very young stars.
Jets of material expelled from a protostar perpendicular to the surrounding protostellar disk.
Remnants of fragments of collapsing gas and dust that did not contain enough mass to initiate core nuclear fusion. Such objects are then frozen somewhere along their pre-main-sequence contraction phase, continually cooling into compact dark objects. Because of their small size and low temperature they are extremely difficult to detect observationally.
A graphical representation of a star's life, as a path on the H-R diagram.
Tightly bound, roughly spherical collection of hundreds of thousands, and sometimes millions, of stars spanning about 50 parsecs. Globular clusters are distributed in the halos around the Milky Way and other galaxies.
Loosely bound collection of tens to hundreds of stars, a few parsecs across, generally found in the plane of the Milky Way.