A super-Earth orbiting the nearby M dwarf GJ 536

Mascareño, A. Suárez; Hernández, J. I. González; Rebolo, R.; Astudillo-Defru, N.; Bonfils, X.; Bouchy, F.; Delfosse, X.; Forveille, T.; Lovis, C.; Mayor, M.; Murgas, F.; Pepe, F.; Santos, N. C.; Udry, S.; Wünsche, A.; Velasco, Sergio

doi:10.1051/0004-6361/201629291

Cited by 29 publications

(25 citation statements)

References 51 publications

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“…Rotation periods estimated according to the formalism described in this Appendix, plotted against the rotation periods for a sample of FGK stars with known values for P rot . Black symbols correspond to stars from Noyes et al (1984) and cyan symbols to stars from Suárez Mascareño et al (2015). The dashed lines mark the interval ±5 days with respect to the diagonal.…”

Section: Discussionmentioning

confidence: 99%

Incidence of debris discs around FGK stars in the solar neighbourhood

Montesinos

Eiroa

Krivov

et al. 2016

A&A

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Context. Debris discs are a consequence of the planet formation process and constitute the fingerprints of planetesimal systems. Their solar system's counterparts are the asteroid and Edgeworth-Kuiper belts. Aims. The aim of this paper is to provide robust numbers for the incidence of debris discs around FGK stars in the solar neighbourhood. Methods. The full sample of 177 FGK stars with d ≤ 20 pc proposed for the DUNES survey is presented. Herschel/PACS observations at 100 and 160 µm complemented in some cases with data at 70 µm, and at 250, 350 and 500 µm SPIRE photometry, were obtained. The 123 objects observed by the DUNES collaboration were presented in a previous paper. The remaining 54 stars, shared with the DEBRIS consortium and observed by them, and the combined full sample are studied in this paper. The incidence of debris discs per spectral type is analysed and put into context together with other parameters of the sample, like metallicity, rotation and activity, and age.Results. The subsample of 105 stars with d ≤ 15 pc containing 23 F, 33 G and 49 K stars, is complete for F stars, almost complete for G stars and contains a substantial number of K stars to draw solid conclusions on objects of this spectral type. The incidence rates of debris discs per spectral type are 0.26 +0.21 −0.14 (6 objects with excesses out of 23 F stars), 0.21 +0.17 −0.11 (7 out of 33 G stars) and 0.20 +0.14 −0.09 (10 out of 49 K stars), the fraction for all three spectral types together being 0.22 +0.08 −0.07 (23 out of 105 stars). The uncertainties correspond to a 95% confidence level. The medians of the upper limits of L dust /L * for each spectral type are 7.8 × 10 −7 (F), 1.4 × 10 −6 (G) and 2.2 × 10 −6 (K); the lowest values being around 4.0 × 10 −7 . The incidence of debris discs is similar for active (young) and inactive (old) stars. The fractional luminosity tends to drop with increasing age, as expected from collisional erosion of the debris belts.

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Section: Discussionmentioning

confidence: 99%

Incidence of debris discs around FGK stars in the solar neighbourhood

Montesinos

Eiroa

Krivov

et al. 2016

A&A

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“…In the case of M-dwarfs, due to the huge number of line blends, the cross correlation function is not Gaussian resulting in a less precise RV measurement and in a loss of sensitivity to the changes in the full width half maximum (FWHM) of the CCF. For this type of stars we opted to do a different modelling of the cross correlation function, using the combination of a second order polynomial with a Gaussian function over a 15 km s −1 window centred at the minimum of the CCF following Suárez Mascareño et al (2017). The center of the Gaussian function is taken as our radial velocity measurement.…”

Section: Radial Velocitiesmentioning

confidence: 99%

Characterization of the radial velocity signal induced by rotation in late-type dwarfs

Mascareño

Rebolo

Hernández

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We investigate the activity induced signals related to rotation in late type stars (FGKM). We analyse the Ca II H&K, the H α and the radial velocity time-series of 55 stars using the spectra from the HARPS public database and the light-curves provided by the ASAS survey. We search for short term periodic signals in the timeseries of activity indicators as well as in the photometric light-curves. Radial velocity data sets are then analysed to determine the presence of activity induced signals. We measure a radial velocity signal induced by rotational modulation of stellar surface features in 37 stars, from late F-type to mid M-type stars. We report an empirical relationship, with some degree of spectral type dependency, between the mean level of chromospheric emission measured by the log 10 (R HK ) and the measured radial velocity semi amplitude. We also report a relationship betweeen the semi amplitude of the chromospheric measured signal and the semi amplitude of the radial velocity induced signal, which strongly depends on the spectral type. We find that for a given strength of chromospheric activity (i.e. a given rotation period) M-type stars tend to induce larger rotation related radial velocity signals than G and K-type stars.

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“…This therefore needs to be kept in mind when attempting to compare absolute values with other works. We focus our analysis on long-term variability rather than on variability at the rotational timescale, as has been done by Suárez Mascareño et al (2017), and we also study a much larger sample. We note we focus here on the line shifts and not on the asymmetries of the lines that are due to convection or other effects such as rotation (Gray 1986).…”

Section: Introductionmentioning

confidence: 99%

Variability of stellar granulation and convective blueshift with spectral type and magnetic activity

Meunier

Lagrange

Kabuiku

et al. 2016

A&A

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Context. In solar-type stars, the attenuation of convective blueshift by stellar magnetic activity dominates the RV (radial velocity) variations over the low amplitude signal induced by low mass planets. Models of stars that differ from the Sun will require a good knowledge of the attenuation of the convective blueshift to estimate its impact on the variations. Aims. It is therefore crucial to precisely determine not only the amplitude of the convective blueshift for different types of stars, but also the dependence of this convective blueshift on magnetic activity, as these are key factors in our model producing the RV. Methods. We studied a sample of main sequence stars with spectral types from G0 to K2 and focused on their temporally averaged properties: the activity level and a criterion allowing to characterise the amplitude of the convective blueshift. This criterion is derived from the dependence of the convective blueshift with the intensity at the bottom of a large set of selected spectral lines. Results. We find the differential velocity shifts of spectral lines due to convection to depend on the spectral type, the wavelength (this dependence is correlated with the Teff and activity level), and on the activity level. This allows us to quantify the dependence of granulation properties on magnetic activity for stars other than the Sun. We are indeed able to derive a significant dependence of the convective blueshift on activity level for all types of stars. The attenuation factor of the convective blueshift appears to be constant over the considered range of spectral types. We derive a convective blueshift which decreases towards lower temperatures, with a trend in close agreement with models for Teff lower than 5800 K, but with a significantly larger global amplitude. Differences also remain to be examined in detail for larger Teff. We finally compare the observed RV variation amplitudes with those that could be derived from our convective blueshift using a simple law and find a general agreement on the amplitude. We also show that inclination (viewing angle relative to the stellar equator) plays a major role in the dispersion in RV amplitudes. Conclusions. Our results are consistent with previous results and provide, for the first time, an estimation of the convective blueshift as a function of Teff, magnetic activity, and wavelength, over a large sample of G and K main sequence stars.

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A super-Earth orbiting the nearby M dwarf GJ 536

Cited by 29 publications

References 51 publications

Incidence of debris discs around FGK stars in the solar neighbourhood

Incidence of debris discs around FGK stars in the solar neighbourhood

Characterization of the radial velocity signal induced by rotation in late-type dwarfs

Variability of stellar granulation and convective blueshift with spectral type and magnetic activity

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