J/MNRAS/460/3706 Radial velocity curves of ν Oct (Ramm+, 2016)
The conjectured S-type retrograde planet in ν Octantis:
more evidence including four years of iodine-cell radial velocities.
Ramm D.J., Nelson B.E., Endl M., Hearnshaw J.B., Wittenmyer R.A., Gunn F.,
Bergmann C., Kilmartin P., Brogt E.
<Mon. Not. R. Astron. Soc., 460, 3706-3719 (2016)>
=2016MNRAS.460.3706R 2016MNRAS.460.3706R (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic ; Radial velocities
Keywords: techniques: radial velocities -
planets and satellites: dynamical evolution and stability -
binaries: spectroscopic - stars: individual: nu Oct
Abstract:
We report 1212 radial-velocity (RV) measurements obtained in the years
2009-2013 using an iodine cell for the spectroscopic binary ν
Octantis (K1 III/IV). This system (abin∼2.6au, P∼1050d) is
conjectured to have a Jovian planet with a semimajor axis half that of
the binary host. The extreme geometry only permits long-term stability
if the planet is in a retrograde orbit. Whilst the reality of the
planet (P∼415d) remains uncertain, other scenarios (stellar
variability or apsidal motion caused by a yet unobserved third star)
continue to appear substantially less credible based on
cross-correlation function bisectors, line-depth ratios and many other
independent details. If this evidence is validated but the planet is
disproved, the claims of other planets using RVs will be seriously
challenged. We also describe a significant revision to the previously
published RVs and the full set of 1437 RVs now encompasses nearly 13
yr. The sensitive orbital dynamics allow us to constrain the 3D
architecture with a broad prior probability distribution on the mutual
inclination, which with posterior samples obtained from an N-body
Markov chain Monte Carlo is found to be 152.5+0.7-0.6°. None
of these samples are dynamically stable beyond 106yr. However, a
grid search around the best-fitting solution finds a region that has
many models stable for 107yr, and includes one model within 1σ
that is stable for at least 108yr. The planet's exceptional nature
demands robust independent verification and makes the theoretical
understanding of its formation a worthy challenge.
Description:
All spectroscopic observations were obtained at University of
Canterbury Mt John Observatory, Lake Tekapo, New Zealand using the 1-m
McLellan telescope and the echelle spectrograph HERCULES.
From the start of operations in 2001 until 2006/7 the detector was a
1kx1k detector. Initial testing of a complete-wavelength-coverage
4kx4k detector began in 2006 October. This detector was then
removed briefly and the original detector used until the 4kx4k CCD
was installed permanently in early 2007.
Objects:
-------------------------------------------
RA (2000) DE Designation(s)
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21 41 28.65 -77 23 24.2 nu Oct = HR 8254
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 48 1180 List of the 1180 austral-processed I2 spectra
acquired during 2009-2013 using the 4kx4k CCD
table4.dat 48 32 List of the relative velocity data of 32 4kx4k
detector observations acquired 2006-2013 using
CCF fitting
table5.dat 48 225 List of the 225 spectra acquired during
2001-2007 using the 1kx1k CCD
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Byte-by-byte Description of file: table3.dat table4.dat table5.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 d JD Barycentric-corrected Julian date (JD-2450000)
13- 19 F7.3 km/s VI2 Corrected I2 relative radial velocity
24- 27 F4.1 m/s e_VI2 Internal error on VI2 (σi)
31- 38 F8.4 km/s bary.corr Barycentric correction
46- 48 I3 --- S/N Signal-to-noise ration in order n=110
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Nov-2017