No planet for HD 166435

“…we began a campaign of highprecision photometric observations with an automatic photoelectric telescope (APT) at Fairborn Observatory in Arizona to search for planetary transits and made tentative plans to announce the new planet at the Protostars and Planets IV conference (Mannings et al. 2000).”

“This phenomena is observed on the Sun to a lesser degree where leader spots tend to be larger and to live longer than follower spots, resulting in a displacement up to 5 0 between the photocenters of the spot and the associated plages (Dobson-Hockey & Radick 1986).”

“From 1998 June to 1998 August, 141 Ca II H and K measurements were made on 20 nights with the 100-inch telescope at Mount Wilson Observatory as part of the HK Project (Baliunas et al. 1998).”

“In addition to the stellar radial velocity, the cross-correlation function (CCF) provides additional information about features in the averaged spectral lines (see Queloz 1994 for a review).”

“…stars are bright enough to permit precise photometric and chromospheric monitoring by telescopes of modest size, permitting careful assessment of velocity jitter, starspots, and possible transits, e.g., Henry (1999); Henry et al. (2000); Queloz et al. (2001); Eaton, Henry, & Fekel (2003).”

“While its barycenter measures the radial-velocity, its bisector inverse slope (BIS – Queloz et al. 2001) and its full width half maximum (FWHM) can diagnose inhomogeneities of the stellar surface.”

“When RV variations are the result of a blended spectrum between a star and an eclipsing binary, we expect the bisectors to reveal a phasemodulated line asymmetry (Queloz et al. 2001; Mandushev et al. 2005).”

“…Observatory, University of California at Santa Cruz, Santa Cruz, CA 95064 – 2 – stellar surface can produce variations in the measured radial velocity of a star and may even mimic the signature of planetary companions (Henry, Donahue, & Baliunas (2002); Queloz et al. (2001); Santos et al. (2003)).”

“Queloz et al. (2001) and Paulson et al. (2004) have shown that photospheric features such as spots and plages on solartype stars can result in low-amplitude, periodic radial velocity variations capable of mimicking the presence of a planetary companion.”

“Finally, we checked that the radial velocity variations are not partly due to stellar radial velocity jitter by computing the bisector velocity span of the cross-correlation function, which traces possible line shape variations 18 .”

“…to right are given: Julian date, radial-velocity RV , the estimated error σRV on the RV, the full width at half-maximum (FWHM) and the line bisector of (BIS) of the cross-correlation function (as defined in Queloz et al. (2001)), the Ca II activity indicator log(R′HK) and its error σlog(R′ HK ).”

“Queloz et al. (2001) reported the remarkable case of HD 166435, a young G0V star with quasi-period radial velocities that were correlated to line bisector variations and Ca II emission.”

“Currently, if significant signals can be detected in activity diagnostics, it is at least a warning that prospective Doppler signals may be spurious (Queloz et al. 2001).”

“For example, Queloz et al. (2001) and Paulson et al. (2004) have shown that photospheric features were the source of periodic RV variations in the young G0 V star HD 166435 and in several Hyades dwarfs.”

“As for the case of HD 166435 presented in Queloz et al. (2001), an anti-correlation between spans and velocities is expected in the case of star-spot induced line-profile variations.”

“We measured the asymmetries of the CCF peaks using the line-bisector method of Queloz et al. (2001).”

“…velocities is “jitter” due, in part, to flows and inhomogeneities on the stellar surface that can produce variations in the measured radial velocity of a star, and can even mimic the signature of planetary companions (Henry, Donahue, & Baliunas (2002); Queloz et al. (2001); Santos et al. (2003)).”

“In this case it has been shown (e.g. Queloz et al. 2001) that the bisector span (BS) of spectral lines in the blended spectrum varies in phase with the radial velocity signal itself, with similar amplitude.”

“Blending of the light with other stars is the most serious concer”

“Finally, any asymmetries in the line profiles were explored by measuring the velocity span of the line-bisector (Gray 1988) according to the techique outlined in Queloz et al. (2001).”

“These periodic variations induce signals in the RV data that could be wrongly interpreted as of planetary origin (e.g. Queloz et al. 2001; Robertson et al. 2014; Sarkis et al. Article number, page 1 of 15 ar X iv :1 81 0.”

“First, the bisector shape of the lines is estimated on the cross-correlation function (inverse bisector slope) in the same way as in Queloz et al. (2001a).”

“The typical precision obtained with CORALIE is ∼ 3m s−1 for bright stars (Queloz et al. 2001b).”

“As the star rotates, a spot, or a plage, moves across the stellardisk and produces an apparent Doppler shift (Saar & Donahue 1997; Queloz et al. 2001; Huélamo et al. 2008; Lagrange et al. 2010).”

“The anti-correlation that exists between RV and bisector span (the measurement of the spectral line asymmetry) is currently used as a signature of RV variations induced by stellar activity (e.g. Queloz et al. 2001; Hatzes et al. 2002).”

“Queloz et al. (2001) and Paulson et al. (2004) have published several examples of periodic radial velocity variations in solar-type stars caused by photospheric spots and plages.”

“To test the hypothesis that the RV variations are due to spectral line distortions caused by a blended eclipsing binary, a line-bisector analysis (Queloz et al. 2001) of the CORALIE and HARPS cross-correlation functions was performed.”

“To test this, we computed the BIS values for our CORALIE measurements (for the definition see Queloz et al. 2001).”

“Following the method outlined by Queloz et al. (2001), we computed the bissector of the photospheric cross-correlation function (CCF) at each phase (cf. Fig.”

“Spectroscopy is often a crucial step in the vetting process, as it allows not only to measure the mass of a planet but also to examine any changes in the line profiles (bisector spans) that might indicate a false positive (see Queloz et al. 2001; Torres et al. 2005).”

“To distinguish between these hypotheses, we use two well-known diagnostics, the bisector velocity span of the cross-correlation function (Hatzes 1996; Queloz et al. 2001) and the CaII H&K activity index (S-index).”

“In that case the “bisector span” of the average spectral line should vary periodically with amplitude and phase similar to the measured velocities themselves (Queloz et al. 2001; Mandushev et al. 2005).”

“Queloz et al. (2001) and Paulson et al. (2004) have presented several examples of periodic radial velocity variations in solar-type stars caused by photospheric spots and plages.”

“Observationally, these inhomogeneities translate into flux variations, as well as into changes of both the shape and the centroid of spectral lines (Saar & Donahue 1997; Queloz et al. 2001).”

“This case is similar to the one of HD 166 435 (Queloz et al. 2001).”

“…measurements were carried out with the HARPS spectrograph on the 3.6m telescope (La Silla, Chile) in order to perform the line-bisector analysis to look for asymmetries in the spectral line profiles, as could be caused by contamination from an unresolved eclipsing binary (Queloz et al. 2001).”

“The profile of Ca II H and K lines is used as an observational proxy of the activity (e.g., Wilson, 1966; Kraft, 1967; Saar and Fischer, 2000; Queloz et al., 2001; Wright et al., 2004), while Ha line is also becoming more widely used as an activity tracer for low-mass stars (e.”

“Within the measurement error (∼0.5 km s 1), the RVs are constant with a mean velocity of and a scatter of 10.56 km s 0.55 .”

“…profiles arising from contamination of the spectrum by the presence of a binary with a period of 5.63 days, we would expect the bisector spans (which measure line asymmetry) to vary with this period and with an amplitude similar to the velocities (see, e.g., Queloz et al. 2001; Torres et al. 2005).”

“• Detached eclipsing binaries: He lminiak et al. (2014) and Coronado et al. (2015) presented the orbital and physical parameters of two new detached eclipsing systems that were identified from ASSAS photometry, and then followed-up with the FEROS, CORALIE, HARPS and PUCHEROS spectrographs.”

“The cross-correlation function (CCF) bisector span (Queloz et al. 2001) and FWHM values are plotted in Fig.”

“Queloz et al. (2001) and Paulson et al. (2004) have documented several examples of solar-type stars whose periodic radial velocity variations were caused by stellar activity.”

“We measured the asymmetries of the CCF peaks using the linebisector method as a function of RV (Gray 1988), as applied by Queloz et al. (2001).”

“These correlations are often a powerful diagnostic to decide if the observed RV signal is of activity or planetary origin (e.g. Boisse et al. 2009; Bonfils et al. 2007; Queloz et al. 2001).”

“C-0488(E) duced by extra-solar planets (Queloz et al. 2001; Bonfils et al. 2007; Huélamo et al. 2008).”

“Queloz et al. (2001) and Paulson et al. (2004) have found periodic radial velocity variations in solartype stars that are caused by starspots.”

“This fact isin agreement with an observed stellar activity (Queloz et al. 2001) and model of a dark spot rotating with the stellar surface and moving in and out of view.”

“Since the 8.6- day stellar rotation period and the 3.4-day planetary orbital period are well separated, the radial velocity variations are clearly due to planetary reflex motion with very little jitter caused by surface activity (e.g., Queloz et al. 2001; Paulson et al. 2004).”

“As shown by Queloz et al. (2001) and Paulson et al. (2004), such photospheric features can result in periodic radial velocity variations capable of mimicking the presence of a planetary companion.”

“One effective technique to distinguish between the planetary hypothesis and the others is to examine variations of spectral line shapes via line bisectors (e.g., Queloz et al. 2001).”

“Table 1 presents the RV measurements of WASP-19 at each Barycentric Julian date, the 1σ Poisson errors on the velocities, and the line bisector span measurements (Gray 1988; Queloz et al. 2001).”

“Photometric variations in the young rapidly rotating stars HD 166435 (Queloz et al. 2001) and HD 19632 (Butler et al. 2002b) argue against Keplerian motion as the cause of the 51 Peg–like velocity variations.”

“Line bisector variations helped establish that surface features were the cause of the RV variations in the main sequence star HD 166435 (Queloz et al. 2001) and the K giant HD 78647 (Setiawan et al. 2004).”

“This has resulted in several false detections (see Queloz et al. (2001); Bonfils et al. (2007); Huélamo et al. (2008); Boisse et al. (2009, 2011); Gregory (2011); Haywood et al. (2014); Santos et al. (2014); Robertson et al. (2014) and many others).”

“These intrinsic variations mimic real radial velocity changes and are very confusing for planet searches (e.g. Queloz et al. 2001; Paulson et al. 2004; Wright 2005).”

“…University Press on behalf of the Royal Astronomical Society its mass.1 A series of diagnostics such as the study of the bisector velocity span (Queloz et al. 2001), or the comparison of the RV signatures obtained using different correlation masks (Bouchy et al. 2009; Dı́az et al. 2012) are…”

“To improve signal-to-noise in the bisector analysis, it is common practice to compute the bisector of the spectrum cross correlation function (Queloz et al. 2001; Santos et al. 2002; Mandushev et al. 2005).”

“These effects may inhibit or even provide false detections (Walker et al. 1992; Santos et al. 2000b; Queloz et al. 2001; Paulson et al. 2002, 2004).”

“…ec 2 01 It can, however, be coherent over the ∼months-long time-scale of the stellar rotation, or over the ∼years-long time-scale of a stellar activity cycle, and can thus be mistaken for the signature of a planetary companion (e.g., Queloz et al. 2001; Bonfils et al. 2007; Robertson et al. 2014).”

“…planets there has always been a concern that the intrinsic variability of the stellar surface (Baliunas et al. 1997) could render impossible the detection of the low amplitude radial velocity (RV) signals caused by terrestrial planets (Queloz et al. 2001; Dumusque et al. 2012; Santos et al. 2014).”

“Briefly, the BIS is a measure of the asymmetry of the average spectral line and should correlate with the RV if the observed offsets are caused by spots or plages rotating with the star (Queloz et al. 2001).”

“Similar disproving evidence has recently been found in at least two other cases that appeared initially to be substellar companions as well (Queloz et al. 2001; Santos et al. 2002).”

“No significant correlation is observed between the radial velocity and the line bisector, suggesting the signal’s origin as planetary rather than due to a blended eclipsing binary system or to stellar activity (see Queloz et al. 2001).”

“If the velocities were the result of a blend with an eclipsing binary, we would expect the line bisectors to vary in phase with the photometric period with an amplitude similar to that of the velocities (Queloz et al. 2001; Mandushev et al. 2005).”

“There is no evidence of a correlation between the velocities and the bisectors, which supports the interpretation that the velocity variations are due to a planetary companion (e.g. Queloz et al. 2001)”

“Stellar noise can conceal and even mimic planetary orbits in RV surveys, and has resulted in many false detections (e.g. CoRoT-7d, Haywood et al. 2014; Alpha Centauri Bb, Rajpaul et al. 2015; HD166435, Queloz et al. 2001; HD99492, Kane et al. 2016; HD200466, Carolo et al. 2014; TW Hydra, Huélamo et al. 2008; HD70573,…”

“The FWHM and BIS are often used as stellar activity indicators (e.g., Queloz et al. 2001).”

“If the velocity variations were the result of a stellar blend, we would expect the bisector spans to vary in phase with the photometric period with an amplitude similar to that seen in the RVs (Queloz et al. 2001; Mandushev et al. 2005).”

“If the RV variations were caused by a background blend (Mandushev et al. 2005) or star spots (Queloz et al. 2001), we would expect the shape of the star’s line bisector to vary in phase with the radial velocities.”

“BIS values indicate the line asymmetry and can be used as a signature of variations caused by stellar activity (e.g. Queloz et al. 2001; Boisse et al. 2011).”

“HD166435 Queloz et al. (2001) published RV variations with a period of 3.7987 days of HD166435 observed during two years.”

“As the star rotates, a spot group, or a plage, moves across the stellar disk and produces an apparent Doppler shift (Saar & Donahue 1997; Queloz et al. 2001; Huélamo et al. 2008; Lagrange et al. 2010).”

“Queloz et al. (2001) and Paulson et al. (2004) have presented several examples of periodic RV variations in solar-type stars caused by photospheric spots and plages.”

“If the RV variations were the result of a blend with an eclipsing binary, we would expect the line bisectors to vary in phase with the photometric period with an amplitude similar to that of the velocities (Queloz et al. 2001; Mandushev et al. 2005).”

“This result indicates that the periodic-radialvelocity change is not due to an blended background binary (as HD41004 - see Santos et al. 2002) nor a dark photospheric stellar spot (as HD166435 - see Queloz et al. 2001).”

“In order to ensure that the radial-velocity variations are not caused by star spots we checked the CCF bisector spans (shown in Figure 4) according to the method described by Queloz et al. (2001).”

“Several studies have shown that those indicators are useful to assess the stellar or planetary nature of a RV signal (e.g. Queloz et al. 2001; Desort et al. 2007; Meunier et al. 2010; Dumusque et al. 2014).”

“…which have a different flux than the solar surface, will break this balance and introduce a variation in the RVs coupled with rotation (Boisse et al. 2011; Queloz et al. 2009; Henry et al. 2002; Queloz et al. 2001; Saar et al. 1998; Saar & Donahue 1997; Baliunas et al. 1983; 1 Vaughan et al. 1981).”

“These inhomogeneities then translate into rotationally modulated changes of both the shape and the centroid of spectral lines (e.g. Saar & Donahue 1997; Queloz et al. 2001).”

“Significant peaks found in the RV data were compared to those found in the activity indicators (log(R′HK), BIS SPAN, and FWHM).”

“Queloz et al. (2001) and Paulson et al. (2004) have found several examples of periodic radial velocity variations in solar-type stars caused by photospheric spots and plages.”

“The most obvious step is to check for periodic modulation in these indicators, which can reveal that a suspected planetary signal is in fact due to activity (see e.g. Queloz et al. 2001; Bonfils et al. 2007).”

“For each star, we tested the hypothesis that the RV variations are due to spectral-line distortions caused by a blended eclipsing binary or star-spots by performing a line-bisector analysis of the crosscorrelation functions (Queloz et al. 2001).”

“The inverse bisector slope is estimated on the crosscorrelation function and its timeseries is also examined, in order to exclude the stellar variability as origin of the observedra ialvelocity variation (Queloz et al. 2001).”

“In the most extreme cases, shifting line centroids can masquerade as dynamical Doppler variations (Queloz et al. 2001).”

“It has been found that chromospheric activity can mask or in some cases exhibit planetary radial-velocity signatures (e.g. Queloz et al. 2001; Henry et al. 2002).”

“Briefly, BIS is a measure of the stellar line asymmetry and should correlate with the RVs if the observed offsets are caused by spots or plages rotating with the star (Queloz et al., 2001).”

“…published after, as the present one, reject this detection. face inhomogeneities, such as plages and spots, which can bre k the balance between light emitted in the red-shifted and the blue-shifted parts of a rotating star (e.g. Saar & Donahue 1997; Queloz et al. 2001; Desort et al. 2007).”

“In particular, the line bisector has become a common tool for confirming exoplanet discoveries (e.g. Hatzes, Cochran, & Bakker 1988; Queloz et al. 2001).”

“The RV measurements were performed using cross-correlation against a numerical mask generated from a G2-type star are given in Table 1, where we also provide the bisector span, BS, which measures the asymmetry of the cross-correlation function (Queloz et al. 2001).”

“…et al. 2012; Boisse et al. 2009), bisector of spectral lines or of the cross correlation function depending on the activity level of the star (e.g., Dumusque et al. 2014a; Figueira et al. 2013; Queloz et al. 2001; Vogt et al. 1987), or the calcium chromospheric activity index (Noyes et al. 1984).”

“When radial velocity variations are the result of a blended spectrum between a star and an eclipsing binary, we expect the bisectors to reveal a phase-modulated line asymmetry (Queloz et al. 2001; Mandushev et al. 2005).”