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J/A+A/506/1469      theta Cyg radial velocity variations     (Desort+, 2009)

Extrasolar planets and brown dwarfs around A-F type stars. VII. theta Cygni radial velocity variations: planets or stellar phenomenon? Desort M., Lagrange A.-M., Galland F., Udry S., Montagnier G., Beust H., Boisse I., Bonfils X., Bouchy F., Delfosse X., Eggenberger A., Ehrenreich D., Forveille T., Hebrard G., Loeillet B., Lovis C., Mayor M., Meunier N ., Moutou C., Pepe F., Perrier C., Pont F., Queloz D., Santos N.C., Segransan D., Vidal-Madjar A. <Astron. Astrophys. 506, 1469 (2009)> =2009A&A...506.1469D
ADC_Keywords: Stars, double and multiple ; Planets ; Radial velocities Keywords: techniques: radial velocities - stars: early-type - stars: planetary systems - stars: individual: theta Cygni Abstract: In the frame of the search for extrasolar planets and brown dwarfs around early-type main-sequence stars, we present the results obtained on the early F-type star theta Cygni. ELODIE and SOPHIE at Observatoire de Haute-Provence (OHP) were used to obtain 91 and 162 spectra, respectively. Our dedicated radial-velocity measurement method was used to monitor the star's radial velocities over five years. We also use complementary, high angular resolution and high-contrast images taken with PUEO at CFHT. We show that theta Cygni radial velocities are quasi-periodically variable, with a ∼150-day period. These variations are not due to the ∼0.35M stellar companion that we detected in imaging at more than 46AU from the star. The absence of correlation between the bisector velocity span variations and the radial velocity variations for this 7km/s vsini star, as well as other criteria indicate that the observed radial velocity variations are not due to stellar spots. The observed amplitude of the bisector velocity span variations also seems to rule out stellar pulsations. However, we observe a peak in the bisector velocity span periodogram at the same period as the one found in the radial velocity periodogram, which indicates a probable link between these radial velocity variations and the low amplitude lineshape variations which are of stellar origin. Long-period variations are not expected from this type of star to our knowledge. If a stellar origin (hence of new type) was to be confirmed for these long-period radial velocity variations, this would have several consequences on the search for planets around main-sequence stars, both in terms of observational strategy and data analysis. An alternative explanation for these variable radial velocities is the presence of at least one planet of a few Jupiter masses orbiting at less than 1AU; however this planet alone does not explain all observed features, and the theta Cygni system is obviously more complex than a planetary system with 1 or 2 planets. The available data do not allow to distinguish between these two possible origins. A vigourous follow-up in spectroscopy and photometry is needed to get a comprehensive view of the star intrinsic variability and/or its surrounding planetary system. Objects: ---------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------- 19 36 26.5 +50 13 16 theta Cyg = HR 7469 ---------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file elodie.dat 33 91 Relative radial velocity measured with ELODIE sophie.dat 33 162 Relative radial velocity measured with SOPHIE
See also: J/A+A/491/883 : Radial velocities of HD 60532 (Desort+, 2008) Byte-by-byte Description of file: elodie.dat sophie.dat
Bytes Format Units Label Explanations
1- 14 F14.6 d JD Julian Date 16- 24 F9.6 km/s RV Relative Radial velocity 26- 33 F8.6 km/s e_RV rms uncertainty on RV
Acknowledgements: Morgan Desort, mdesort(at) References: Galland et al., Paper I 2005A&A...443..337G Galland et al., Paper II 2005A&A...444L..21G Galland et al., Paper III 2006A&A...447..355G Galland et al., Paper IV 2006A&A...452..709G Desort et al., Paper V 2008A&A...491..883D, Cat. J/A+A/491/883 Lagrange et al., Paper VI 2009A&A...495..335L
(End) Morgan Desort [LAOG, France], Patricia Vannier [CDS] 01-Sep-2009
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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