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BINARY CENTRAL STARS OF PLANETARY NEBULAE DISCOVERED THROUGH PHOTOMETRIC VARIABILITY. V. THE CENTRAL STARS OF HaTr 7 AND ESO 330-9

Journal Article · · The Astronomical Journal (Online)
; ;  [1];  [2];  [3];  [4]
  1. Department of Physics and Astronomy, Valparaiso University, Valparaiso, IN 46383 (United States)
  2. Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong SAR (China)
  3. Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom)
  4. Gemini Observatory, Southern Operations Center, Casilla 603, La Serena (Chile)
We find the central stars (CSs) of the planetary nebulae (PNe) HaTr 7 and ESO 330-9 to be close-binary systems. Both have orbital periods of less than half a day and contain an irradiated cool companion to the hot CS. We provide light curves, spectra, radial velocity curves, orbital periods, and binary modeling results for both systems. The binary modeling leads to system parameters, or ranges of allowed parameters for each system. We find that for the CS of HaTr 7 we need to use limb-darkening values for the cool companion that are different than the expected values for an isolated star. We also fit the CS spectrum to determine logg and temperature values independent of the binary modeling. For ESO 330-9 we find that based on our binary modeling, the hot CS is most likely a post-red giant branch (RGB) star with a mass of around 0.4 M{sub ⊙}. We discuss our derived stellar and nebular parameters in the broader context of close-binary CSs and their surrounding planetary nebulae (PNe). We also discuss the present status of known or suspected post-RGB stars in PNe.
OSTI ID:
22863158
Journal Information:
The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 1 Vol. 153; ISSN 1538-3881
Country of Publication:
United States
Language:
English

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