{
  "id": "2210.11649",
  "version": "v1",
  "published": "2022-10-21T00:35:38.000Z",
  "updated": "2022-10-21T00:35:38.000Z",
  "title": "Evolved Eclipsing Binaries and the Age of the Open Cluster NGC 752",
  "authors": [
    "Eric L. Sandquist",
    "Andrew J. Buckner",
    "Matthew D. Shetrone",
    "Samuel C. Barden",
    "Catherine A. Pilachowski",
    "Constantine P. Deliyannis",
    "Dianne Harmer",
    "Robert Mathieu",
    "Soren Meibom",
    "Soren Frandsen",
    "Jerome A. Orosz"
  ],
  "comment": "34 pages, 23 figures, accepted for Astronomical Journal",
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA"
  ],
  "abstract": "We present analyses of improved photometric and spectroscopic observations for two detached eclipsing binaries at the turnoff of the open cluster NGC 752: the 1.01 day binary DS And and the 15.53 d BD $+$37 410. For DS And, we find $M_1 = 1.692\\pm0.004\\pm0.010 M_\\odot$, $R_1 = 2.185\\pm0.004\\pm0.008 R_\\odot$, $M_2 = 1.184\\pm0.001\\pm0.003 M_\\odot$, and $R_2 = 1.200\\pm0.003\\pm0.005 R_\\odot$. We either confirm or newly identify unusual characteristics of both stars in the binary: the primary star is found to be slightly hotter than the main sequence turn off and there is a more substantial discrepancy in its luminosity compared to models (model luminosities are too large by about 40%), while the secondary star is oversized and cooler compared to other main sequence stars in the same cluster. The evidence points to non-standard evolution for both stars, but most plausible paths cannot explain the low luminosity of the primary star. BD $+$37 410 only has one eclipse per cycle, but extensive spectroscopic observations and the TESS light curve constrain the stellar masses well: $M_1 = 1.717\\pm0.011 M_\\odot$ and $M_2 = 1.175\\pm0.005 M_\\odot$. The radius of the main sequence primary star near $2.9R_\\odot$ definitively requires large convective core overshooting ($> 0.2$ pressure scale heights) in models for its mass, and multiple lines of evidence point toward an age of $1.61\\pm0.03\\pm0.05$ Gyr (statistical and systematic uncertainties). Because NGC 752 is currently undergoing the transition from non-degenerate to degenerate He ignition of its red clump stars, BD $+$37 410 A directly constrains the star mass where this transition occurs.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-10-21T00:35:38.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "open cluster ngc",
      "evolved eclipsing binaries",
      "spectroscopic observations",
      "evidence point",
      "main sequence primary star"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 34,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}