% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Arunima:1008566,
      author       = {Arunima, Arunima and Pfalzner, Susanne and Govind, Amith},
      title        = {{U}nbound stars hold the key to young star cluster history},
      journal      = {Astronomy and astrophysics},
      volume       = {670},
      issn         = {0004-6361},
      address      = {Les Ulis},
      publisher    = {EDP Sciences},
      reportid     = {FZJ-2023-02399},
      pages        = {A128},
      year         = {2023},
      abstract     = {Aims.Gaia delivers the positions and velocities of stars at
                      an unprecedented precision. Therefore, for star clusters,
                      there exists much higher confidence in whether a specific
                      star is a member of a particular cluster or not. However,
                      membership determination is still especially challenging for
                      young star clusters. At ages 2−10 Myr, the gas is
                      expelled, ending the star formation process and leading to
                      their expansion, while at the same time, many former members
                      become unbound. As a first step, we aim to assess the
                      accuracy of the methods commonly used to distinguish between
                      bound and unbound cluster members; after identifying the
                      most suitable technique for this task, we wish to understand
                      which of the two populations is more suited to provide
                      insights into the initial configuration and the dynamical
                      history of a cluster starting from its currently observed
                      properties. Methods: Here, we perform N-body simulations of
                      the dynamics of such young star clusters. We investigate how
                      cluster dynamics and observational limitations affect the
                      recovered information about the cluster from a theoretical
                      perspective. Results: We find that the much-used method of
                      distance and velocity cutoffs for membership determination
                      often leads to false negatives and positives alike. Often
                      observational studies focus on the stars remaining bound.
                      However, bound stars quickly lose the memory of the pre-gas
                      expulsion phase due to their ongoing interaction with their
                      fellow cluster members. Our study shows that it is the
                      unbound stars that hold the key to charting a cluster's
                      dynamic history. Backtracking unbound stars can provide the
                      original cluster size and determine the time of gas
                      expulsion - two parameters that are currently still poorly
                      constrained. This information is lost in the bound
                      population. In addition, former members are often better
                      indicators for disc lifetimes or initial binary fractions.
                      We apply the backtracking analysis, with varying success, to
                      the clusters: Upper Scorpius and NGC 6530. For highly
                      substructured clusters such as Upper Scorpius, backtracking
                      to the individual subcluster centres will provide better
                      results in future.},
      cin          = {JSC},
      ddc          = {520},
      cid          = {I:(DE-Juel1)JSC-20090406},
      pnm          = {5111 - Domain-Specific Simulation $\&$ Data Life Cycle Labs
                      (SDLs) and Research Groups (POF4-511)},
      pid          = {G:(DE-HGF)POF4-5111},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000940896300006},
      doi          = {10.1051/0004-6361/202245242},
      url          = {https://juser.fz-juelich.de/record/1008566},
}