An Investigation of the Small Eccentricity in the Spectroscopic Binary System ζ TrA

Details An Investigation of the Small Eccentricity in the Spectroscopic Binary System ζ TrA An Investigation of the Small Eccentricity in the Spectroscopic Binary System ζ TrA

Aug 2007

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007iaus..240..118k&link_type=abstract

Binary Stars as Critical Tools and Tests in Contemporary Astrophysics, International Astronomical Union. Symposium no. 240, he

Astronomy and Astrophysics

Astrophysics

Scientific paper

The orbital eccentricity of the SB1 system ζ TrA (S.T. F9V, P ~ 13 d) was found by Skuljan et al. (2004) to be e = 0.01398 ± 0.00019. Lucy (2005) devised a statistical test of the significance of this result based on the amplitude and phase of the third harmonic in the Fourier analysis of the radial velocity data, and concluded that the non-zero eccentricity measured does not arise from a slightly eccentric Keplerian orbit, but from proximity effects in the binary. He therefore believes a circular orbit should be assigned to this system. In this paper, we investigate one possible proximity effect, namely the tidal distortion of the primary star, such that the measured Doppler shift does not accurately indicate the centre of mass radial velocity of the star as a whole. The code of Wilson and Devinney (2003) was used to model the tidal distortion of the measured radial velocities, assuming a range of possible secondary masses, corresponding to M dwarf companions. The result is that even for the lowest possible mass secondary of 0.09 M[Sun] with sini = 1 (this gives the greatest tidal distortion, as it is closest to the primary) there is no significant effect on the radial velocities (the differences are of order 1 m/s as a result of the tidal effects). Similar negligible tidal effects arise using a white dwarf companion. We note that the difference between a circular orbit and the observations amounts to as much as 140 m/s at some phases, which is essentially the amplitude of the second harmonic in the data. Our conclusion is that this strong and highly significant second harmonic is most probably the result of a small orbital eccentricity as reported by Skuljan et al. (2004). We note that the observed third harmonic according to Lucy (2005) has an amplitude of only 5.2 ± 2.0 m/s, which is just over twice the error bar of its measurement, and that the predicted third harmonic for an eccentric orbit is only 1.6 m/s.

Affiliated with

Also associated with

No associations

Rating

An Investigation of the Small Eccentricity in the Spectroscopic Binary System ζ TrA does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with An Investigation of the Small Eccentricity in the Spectroscopic Binary System ζ TrA, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and An Investigation of the Small Eccentricity in the Spectroscopic Binary System ζ TrA will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-975610