The relation of the Alpha Persei star cluster with the nearby stellar stream

Abstract

A map of 100 degrees on a side extracted from Gaia DR2 and centred on Alpha Persei reveals two distinct structures | the Alpha Persei star cluster and a conspicuous stellar stream, as widely documented in recent literature. In this work we employ DBSCAN to assess individual stars' membership and attempt at separating stars belonging to the cluster and to the stream from the general field. In turn, we characterize the stream and investigate its relation with the cluster. The stream population turned out to be significantly older (5+/-1Gyr) than the cluster, and to be positioned ~90 pc away from the cluster, in its background. The stream exhibits a sizeable thickness of ~180 pc in the direction of the line of view. Finally, the stream harbours a prominent population of white dwarf stars. We estimated an upper limit of the stream mass of ~6000 solar masses?. The stream would therefore be the leftover of a relatively massive old cluster. The surface density map of the Alpha Persei evidences the presence of tidal tails. While it is tempting to ascribe them to the interaction with the disrupting old star cluster, we prefer to believe, conservatively, they are of Galactic origin.

arXiv comment14 pages, 12 figures, 3 tables. Accepted to The Astronomical Journal

References in corpus (16)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Gaia Data Release 2: using Gaia parallaxes
• Parallaxes and proper motions for 20 open clusters as based on the new Hipparcos catalogue
• The Gaia-ESO Survey: Kinematic structure in the Gamma Velorum Cluster
• Expanding associations in the Vela-Puppis region: 3D structure and kinematics of the young population
• A 5D view of the Alpha Per, Pleiades, and Praesepe clusters
• Uncovering a 260 pc wide, 35 Myr old filamentary relic of star formation
• A stellar relic filament in the Orion star forming region
• Ruprecht 147: a paradigm of dissolving star cluster
• Open-cluster density profiles derived using a kernel estimator
• The low-mass pre-main-sequence population of Sco OB1
• On the mass of the Galactic star cluster NGC 4337
• Determination of Galactic Rotation Parameters and the Solar Galactocentric Distance Ro from 73 Masers
• The Gould Belt

Cited by in corpus (6)

• Lithium depletion boundary, stellar associations, and Gaia
• Tidal tails in the disintegrating open cluster NGC 752
• A $Gaia$ EDR3 search for tidal tails in disintegrating open clusters
• Extended Tidal Tails of IC 4756 detected by {\it Gaia} EDR3
• Unresolved Binaries and Multiples in the Intermediate Mass Range in open clusters: Pleiades, Alpha Per, Praesepe, and NGC 1039
• Photometric Identification of Unresolved Binary Stars in Nearby Open Star Clusters