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Title: THE PTI CARBON STAR ANGULAR SIZE SURVEY: EFFECTIVE TEMPERATURES AND NON-SPHERICITY

We report new interferometric angular diameter observations of 41 carbon stars observed with the Palomar Testbed Interferometer. Two of these stars are CH carbon stars and represent the first such measurements of this subtype. Of these, 39 have Yamashita spectral classes and are of sufficiently high quality that we can determine the dependence of effective temperature on spectral type. We find that there is a tendency for the effective temperature to increase with increasing temperature index by ∼120 K per step, starting at T{sub EFF} ≅ 2500 K for C3, y, although there is a large amount of scatter in this relationship. Overall, the median effective temperature of the carbon star sample is 2800 ± 270 K and the median linear radius is 360 ± 100 R{sub ☉}. We also find agreement, on average within 15 K, with the T{sub EFF} determinations of Bergeat et al. and a refinement of the carbon star angular size prediction based on V and K magnitudes is presented that is good to an rms of 12%. A subsample of our stars have sufficient (u, v) coverage to permit non-spherical modeling of their photospheres, and a general tendency for detection of statistically significant departures frommore » sphericity with increasing interferometric signal-to-noise is seen. The implications of most—and potentially all—carbon stars being non-spherical is considered in the context of surface inhomogeneities and a rotation-mass-loss connection.« less
Authors:
 [1] ; ;  [2] ;  [3] ;  [4]
  1. Lowell Observatory, 1400 W. Mars Hill Rd., Flagstaff, AZ (United States)
  2. Institut für Astronomie, Türkenschanzstr. 17, A-1180 Vienna (Austria)
  3. INAF-OAPD, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy)
  4. California Institute of Technology, 770 South Wilson Avenue, Pasadena, CA (United States)
Publication Date:
OSTI Identifier:
22270932
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 775; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; CARBON STARS; INDEXES; INTERFEROMETERS; INTERFEROMETRY; MASS TRANSFER; PHOTOSPHERE; POTENTIALS; RESOLUTION; ROTATION; SPHERICAL CONFIGURATION; STELLAR WINDS; TEMPERATURE DEPENDENCE