DISCOVERY OF a 1.6 YEAR MAGNETIC ACTIVITY CYCLE IN THE EXOPLANET HOST STAR Ι HOROLOGII

Metcalfe, T. S.; Basu, Sarbani; Henry, Todd J.; Soderblom, David R.; Judge, P. G.; Knölker, M.; Mathur, S.; Rempel, Matthias

doi:10.1088/2041-8205/723/2/l213

Cited by 127 publications

(120 citation statements)

References 41 publications

Supporting

Mentioning

103

Contrasting

Unclassified

Order By: Relevance

“…12) shows power at periods of 5.7 d as well as 7.94 d and 8.45 d (also found by Boisse et al 2011, based on HARPS RVs). The latter peak coincides with periodic variations (8.5 d) found in the S HK index by Metcalfe et al (2010), which therefore probably indicates the rotation of this star. The residual RVs anti-correlate with BIS which is indeed expected for rotating spots (Boisse et al 2011).…”

Section: Discussion On Individual Targetssupporting

confidence: 77%

“…The orbital period of 307 d is different from the rotation period of ∼8 d (see below), while a relation with the magnetic cycle has to be discussed. Metcalfe et al (2010) reported that a magnetic activity cycle of ∼1.6 yr bears no obvious relation to the orbital period, but we find that there is a moderately significant RV-log R HK correlation (Fig. B.9) and that the refined orbital period (307 d) is half of the formal best-fitting period (630 d) for the combined HARPS and SMARTS S HK -index measurements ( Fig.…”

Section: Discussion On Individual Targetsmentioning

confidence: 48%

“…B.9) and that the refined orbital period (307 d) is half of the formal best-fitting period (630 d) for the combined HARPS and SMARTS S HK -index measurements ( Fig. 10; we use the S HK -index instead of log R HK for the comparison, since Metcalfe et al (2010) published S HK -index measurements). However, if the 307 d RV period were caused by a magnetic cycle, we would expect the same period for the S HK -index and a positive correlation with the BIS , while there is a formal RV-BIS anti-correlation probably artificially induced by the shortterm variations (Fig.…”

Section: Discussion On Individual Targetsmentioning

confidence: 99%

See 2 more Smart Citations

The planet search programme at the ESO CES and HARPS

Zechmeister

Kürster

Endl³

et al. 2013

A&A

View full text Add to dashboard Cite

Context. In 1992 we began a precision radial velocity survey for planets around solar-like stars with the Coudé Echelle Spectrograph and the Long Camera (CES LC) at the 1.4 m telescope in La Silla (Chile) resulting in the discovery of the planet ι Hor b. We have continued the survey with the upgraded CES Very Long Camera (VLC) and the HARPS spectrographs, both at the 3.6 m telescope, until 2007. Aims. In this paper we present additional radial velocities for 31 stars of the original sample with higher precision. The observations cover a time span of up to 15 years and permit a search for Jupiter analogues. Methods. The survey was carried out with three different instruments/instrument configurations using the iodine absorption cell and the ThAr methods for wavelength calibration. We combine the data sets and perform a joint analysis for variability, trends, and periodicities. We compute Keplerian orbits for companions and detection limits in case of non-detections. Moreover, the HARPS radial velocities are analysed for correlations with activity indicators (CaII H&K and cross-correlation function shape). Results. We achieve a long-term RV precision of 15 m/s (CES+LC, 1992-1998, 9 m/s (CES+VLC, 1999, and 2.8 m/s (HARPS, 2003(HARPS, -2009, including archive data), respectively. This enables us to confirm the known planetary signals in ι Hor and HR 506 as well as the three known planets around HR 3259. A steady RV trend for Ind A can be explained by a planetary companion and calls for direct imaging campaigns. On the other hand, we find previously reported trends to be smaller for β Hyi and not present for α Men. The candidate planet Eri b was not detected despite our better precision. Also the planet announced for HR 4523 cannot be confirmed. Long-term trends in several of our stars are compatible with known stellar companions. We provide a spectroscopic orbital solution for the binary HR 2400 and refined solutions for the planets around HR 506 and ι Hor. For some other stars the variations could be attributed to stellar activity, as e.g. the magnetic cycle in the case of HR 8323. Conclusions. The occurrence of two Jupiter-mass planets in our sample is in line with the estimate of 10% for the frequency of giant planets with periods smaller than 10 yr around solar-like stars. We have not detected a Jupiter analogue, while the detections limits for circular orbits indicate at 5 AU a sensitivity for minimum mass of at least 1M Jup (2M Jup ) for 13% (61%) of the stars.

show abstract

Section: Discussion On Individual Targetssupporting

confidence: 77%

Section: Discussion On Individual Targetsmentioning

confidence: 48%

Section: Discussion On Individual Targetsmentioning

confidence: 99%

See 1 more Smart Citation

The planet search programme at the ESO CES and HARPS

Zechmeister

Kürster

Endl³

et al. 2013

A&A

View full text Add to dashboard Cite

show abstract

“…This is compatible with the typical duration of an activity cycle, although on the short end (see e.g. Baliunas et al 1995;Fares et al 2009;Metcalfe et al 2010). …”

Section: Bd -114672supporting

confidence: 82%

The HARPS search for southern extra-solar planets

Moutou

Mayor

Curto³

et al. 2011

A&A

View full text Add to dashboard Cite

We are conducting a planet search survey with HARPS since seven years. The volume-limited stellar sample includes all F2 to M0 main-sequence stars within 57.5 pc, where extrasolar planetary signatures are systematically searched for with the radial-velocity technics. In this paper, we report the discovery of new substellar companions of seven main-sequence stars and one giant star, detected through multiple Doppler measurements with the instrument HARPS installed on the ESO 3.6 m telescope, La Silla, Chile. These extrasolar planets orbit the stars HD 1690, HD 25171, HD 33473A, HD 89839, HD 113538, HD 167677, and HD 217786. The alreadypublished giant planet around HD 72659 is also analysed here, and its elements are better determined by the addition of HARPS and Keck data. The other discoveries are giant planets in distant orbits, ranging from 0.3 to 29 M Jup in mass and between 0.7 and 10 years in orbital period. The low metallicity of most of these new planet-hosting stars reinforces the current trend for long-distance planets around metal-poor stars. Long-term radial-velocity surveys allow probing the outskirts of extrasolar planetary systems, although confidence in the solution may be low until more than one orbital period is fully covered by the observations. For many systems discussed in this paper, longer baselines are necessary to refine the radial-velocity fit and derive planetary parameters. The radial-velocity time series of stars BD -114672 and HIP 21934 are also analysed and their behaviour interpreted in terms of the activity cycle of the star, rather than long-period planetary companions.

show abstract

“…The solar-like pattern of anti-correlated changes in the oscillation frequencies and amplitudes suggested a cycle period longer than 120 days, and the size of the shifts showed a similar frequency dependence to that observed in the Sun (Libbrecht & Woodard 1990;Salabert et al 2011). Metcalfe et al (2010) discovered a record-breaking 1.6-year activity cycle in the F8V star ι Hor (HD 17051), which has subsequently been confirmed with X-ray observations of the stellar corona (Sanz-Forcada et al 2013). Most recently, Metcalfe et al (2013) documented dual magnetic cycles with periods of 3 years and 13 years in the K2V star Eri (HD 22049), falling squarely on the two activity sequences identified by Saar & Brandenburg. The Kepler mission represents an unprecedented opportunity to study the short-period magnetic cycles that have been observed in some rapidly rotating F stars.…”

Section: Introductionsupporting

confidence: 61%

Magnetic activity of F stars observed byKepler

Mathur

García

Ballot

et al. 2014

A&A

Self Cite

159

195

View full text Add to dashboard Cite

Context. The study of stellar activity is important because it can provide new constraints for dynamo models when combined with surface rotation rates and the depth of the convection zone. We know that the dynamo mechanism, which is believed to be the main process that rules the magnetic cycle of solar-like stars, results from the interaction between (differential) rotation, convection, and magnetic field. The Kepler mission has already been collecting data for a large number of stars during four years allowing us to investigate magnetic stellar cycles. Aims. We investigated the Kepler light curves to look for magnetic activity or even hints of magnetic activity cycles. Based on the photometric data we also looked for new magnetic indexes to characterise the magnetic activity of the stars. Methods. We selected a sample of 22 solar-like F stars that have a rotation period shorter than 12 days. We performed a timefrequency analysis using the Morlet wavelet yielding a magnetic proxy for our sample of stars. We computed the magnetic index S ph as the standard deviation of the whole time series and the index S ph , which is the mean of standard deviations measured in subseries of length five times the rotation period of the star. We defined new indicators, such as the contrast between high and low activity, to take into account the fact that complete magnetic cycles are not observed for all the stars. We also inferred the Rossby number of the stars and studied their stellar background. Results. This analysis shows different types of behaviour in the 22 F stars. Two stars show behaviour very similar to magnetic activity cycles. Five stars show long-lived spots or active regions suggesting the existence of active longitudes. Two stars in our sample seem to have a decreasing or increasing trend in the temporal variation of the magnetic proxies. Finally, the last group of stars shows magnetic activity (with the presence of spots) but no sign of cycle.

show abstract

DISCOVERY OF a 1.6 YEAR MAGNETIC ACTIVITY CYCLE IN THE EXOPLANET HOST STAR Ι HOROLOGII

Cited by 127 publications

References 41 publications

The planet search programme at the ESO CES and HARPS

The planet search programme at the ESO CES and HARPS

The HARPS search for southern extra-solar planets

Magnetic activity of F stars observed byKepler

Contact Info

Product

Resources

About