Tidal disruption of the aged open cluster Berkeley 17

Abstract

Berkeley 17 is known to show a core-tail morphology. Pan-STARRS 1 photometry complete to gP1 ≈ 21.5 mag reveals the effect of mass segregation between the core and the tail (and an antitail). Furthermore, there is an overall paucity of low-mass member stars — likely as the consequence of tidal stripping by the foreground Perseus arm of this aged (10 Gyr) cluster. Our analysis indicates that about half of the blue straggler candidates suspected to be associated with Berkeley 17 may be field contaminations, and yet some may be confused with blue horizontal-branch stars usually found only in globular clusters. We propose Berkeley 17 to be a remnant super star cluster in the continuing process of disintegration