J/ApJ/681/562 Orbits of 5 Cet and AX Mon (Eaton, 2008)
Spurious eccentricities of distorted binary components.
Eaton J.A.
<Astrophys. J., 681, 562-569 (2008)>
=2008ApJ...681..562E 2008ApJ...681..562E
ADC_Keywords: Binaries, spectroscopic ; Radial velocities
Keywords: binaries: spectroscopic - stars: oscillations -
stars: individual (5 Cet, AX Mon, TT Hya)
Abstract:
I discuss the effect of physical distortion on the velocities of close
binary components and how we may use the resulting distortion of
velocity curves to constrain some properties of binary systems, such
as inclination and mass ratio. Precise new velocities for 5 Cet
convincingly detect these distortions with their theoretically
predicted phase dependence. We can even use such distortions of
velocity curves to test Lucy's theory of convective gravity darkening.
The observed distortions for TT Hya and 5 Cet require the contact
components of those systems to be gravity darkened, probably somewhat
more than predicted by Lucy's theory, but clearly not as much as
expected for a radiative star. These results imply there is no
credible evidence for eccentric orbits in binaries with contact
components. I also present some speculative analyses of the observed
properties of a binary encased in a nonrotating common envelope, if
such an object could actually exist, and discuss how the limb
darkening of some recently calculated model atmospheres for giant
stars may bias my results for velocity-curve distortions, as well as
other results from a wide range of analyses of binary stars.
Description:
The new data we are using here are radial velocities from the
Tennessee State University (TSU) Automatic Spectroscopic Telescope
(AST). These echelle spectra of roughly 30000 resolution cover the
wavelength range 6000-7100Å. We reduced and analyzed them with
standard pipeline techniques to derive the radial velocities for 5 Cet
(HD 352) and AX Mon (HD 45910), given in Table 1.
Objects:
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RA (2000) DE Designation(s)
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00 08 12.1 -02 26 52 5 Cet = HD 352
06 30 32.9 +05 52 01 AX Mon = HD 45910
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 28 303 Spectroscopic data for 5 Cet and AX Mon
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See also:
J/ApJ/484/394 : AX Mon photometry and UV spectra (Elias+ 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d HJD Heliocentric Julian Date
14- 19 F6.2 km/s RV Radial velocity of the cool star (1)
21- 22 A2 --- --- [HD]
24- 28 I5 --- HD HD identification (352 or 45910)
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Note (1): Velocities measured for bright stars such as 5 Cet have an external
precision of ∼0.11km/s RMS (Eaton & Williamson, 2007PASP..119..886E 2007PASP..119..886E).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 26-Oct-2010