The pti carbon star angular size survey: effective temperatures and non-sphericity

van Belle, Gerard T. and Paladini, Claudia and Aringer, Bernhard and Hron, Josef and Ciardi, David (2013) The pti carbon star angular size survey: effective temperatures and non-sphericity. The Astrophysical Journal, 775 (1). pp. 45-63. ISSN 0004-637X

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Abstract

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 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. We also find agreement, on average within 15 K, with the T 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 from 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.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty / Department / School: No Faculty
Date Deposited: 09 Jun 2017 07:23
Last Modified: 27 Jun 2017 04:40
Uncontrolled Keywords: infrared: stars; high angular resolution; interferometers; carbon stars; star distances; star fundamental parameters
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020102 Astronomical and Space Instrumentation
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1088/0004-637X/775/1/45
URI: http://eprints.usq.edu.au/id/eprint/32203

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