Abstract
We search for mass segregation in the intermediate-aged open cluster NGC 6819 within a carefully identified sample of probable cluster members. Using photometry from Gaia, Pan-STARRS, and the Two Micron All Sky Survey as inputs for a Bayesian statistics software suite, BASE-9, we identify a rich population of (photometric) binaries and derive posterior distributions for the cluster age, distance, metallicity, and reddening, as well as star-by-star photometric membership probabilities, masses, and mass ratios (for binaries). Within our entire sample, we identify 2632 cluster members and 777 binaries. We then select a main-sequence “primary sample” with 14.85 <G < 19.5, containing 1342 cluster members and 250 binaries with mass ratios q > 0.5, to investigate mass segregation. Within this primary sample, we find the binary radial distribution is significantly shifted toward the cluster center as compared to the single stars, resulting in a binary fraction that increases significantly toward the cluster core. Furthermore, we find that within the binary sample, more massive binaries have more centrally concentrated radial distributions than less massive binaries. The same is true for the single stars. We verify the expectation of mass segregation for this stellar sample in NGC 6819 through both relaxation time arguments and by investigating a sophisticated N-body model of the cluster. Importantly, this is the first study to investigate mass segregation of the binaries in the open cluster NGC 6819.
| Original language | English (US) |
|---|---|
| Article number | 44 |
| Journal | Astrophysical Journal |
| Volume | 967 |
| Issue number | 1 |
| DOIs | |
| State | Published - May 1 2024 |
Funding
This material is based upon work supported by the National Science Foundation (NSF) under grant No. AST-2149425, a Research Experiences for Undergraduates (REU) grant, and under NSF AAG grant No. AST-2107738. The material contained in this document is also based upon work supported by a National Aeronautics and Space Administration (NASA) grant awarded to the Illinois/NASA Space Grant Consortium. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF or NASA. This research was supported in part through the computational resources and staff contributions provided for the Quest high performance Computing Cluster at Northwestern University which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. We would also like to thank Elizabeth Jefferey, Roger Cohen, Elliot Robinson, and the rest of the BASE-9 group for their insights and support.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science