2001A&A...379..279Q


Query : 2001A&A...379..279Q

2001A&A...379..279Q - Astronomy and Astrophysics, volume 379, 279-287 (2001/11-3)

No planet for HD 166435.

QUELOZ D., HENRY G.W., SIVAN J.P., BALIUNAS S.L., BEUZIT J.L., DONAHUE R.A., MAYOR M., NAEF D., PERRIER C. and UDRY S.

Abstract (from CDS):

The G0V star HD 166435 has been observed by the fiber-fed spectrograph ELODIE as one of the targets in the large extra-solar planet survey that we are conducting at the Observatory of Haute-Provence. We detected coherent, low-amplitude, radial-velocity variations with a period of 3.7987days, suggesting a possible close-in planetary companion. Subsequently, we initiated a series of high-precision photometric observations to search for possible planetary transits and an additional series of CaII H and K observations to measure the level of surface magnetic activity and to look for possible rotational modulation. Surprisingly, we found the star to be photometrically variable and magnetically active. A detailed study of the phase stability of the radial-velocity signal revealed that the radial-velocity variability remains coherent only for durations of about 30days. Analysis of the time variation of the spectroscopic line profiles using line bisectors revealed a correlation between radial velocity and line-bisector orientation. All of these observations, along with a one-quarter cycle phase shift between the photometric and the radial-velocity variations, are well explained by the presence of dark photospheric spots on HD 166435. We conclude that the radial-velocity variations are not due to gravitational interaction with an orbiting planet but, instead, originate from line-profile changes stemming from star spots on the surface of the star. The quasi-coherence of the radial-velocity signal over more than two years, which allowed a fair fit with a binary model, makes the stability of this star unusual among other active stars. It suggests a stable magnetic field orientation where spots are always generated at about the same location on the surface of the star.

Abstract Copyright:

Journal keyword(s): stars: activity - individual: HD 166435 - planetary systems

Simbad objects: 10

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Number of rows : 10
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 BD+19 641 SB* 04 00 39.5296216176 +20 22 49.525011912   9.33   8.2   G4V 76 0
2 Cl Melotte 25 OpC 04 29 47.3 +16 56 53           ~ 3050 0
3 HD 30809 PM* 04 51 23.2149431232 +15 26 00.473427888   8.418 7.886 7.591 7.302 F8 99 0
4 NGC 2632 OpC 08 40 13.0 +19 37 16           ~ 1546 0
5 BD+20 2181 Ro* 08 41 25.8429243867 +19 56 36.848107538   11.342 10.687     G0V 72 0
6 * ksi Boo A PM* 14 51 23.3884659504 +19 06 01.619801424   5.40 4.675     G7Ve 529 0
7 NGC 6475 OpC 17 53 47.3 -34 50 28           ~ 381 0
8 * b Her SB* 18 07 01.5906608928 +30 33 43.584892488 5.52 5.67 5.13 4.61 4.28 F6V 461 0
9 HD 166435 PM* 18 09 21.3816898440 +29 57 06.166145376   7.457 6.829     G1IV 189 0
10 * 51 Peg PM* 22 57 27.9804852576 +20 46 07.797040104 6.39 6.16 5.46 4.97 4.61 G2IV 1154 1

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