Differential Radial Velocities and Stellar Parameters of Nearby Young Stars

Paulson, Diane B.; Yelda, S.

doi:10.1086/504115

Cited by 77 publications

(55 citation statements)

References 44 publications

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“…later than those of our targets, and their detection limit estimation is probably conservative (like our rmsbased method). Our detection limits, even before correcting for activity, are better than those obtained by Paulson & Yelda (2006) on the β Pic moving group; for these targets, their detection limits at short periods fall in the brown dwarf regime, whereas our limits are well within the planet regime for similar periods. We attribute this to the internal precision of their measurements, their adopted observing strategy, and their approach to estimating the detection limits.…”

Section: Comparison With Previous Surveyscontrasting

confidence: 67%

“…To our knowledge, the only significant surveys have been performed by Paulson et al (2004) on 94 stars members of the Hyades (aged about 600 Myr) and on 61 stars members of various moving groups (MGs) or stellar associations aged between 12 and 300 Myr (Paulson & Yelda 2006). In both cases, high spectral resolution data in the range 40 000-70 000 were used.…”

Section: Introductionmentioning

confidence: 99%

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Planets around stars in young nearby associations

Lagrange

Meunier

Chauvin

et al. 2013

A&A

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Context. Stars in young nearby associations are the only targets that allow giant planet searches in the near future, at all separations by coupling indirect techniques, such as radial velocity (RV) and deep imaging. These stars are first priority targets for the forthcoming planet imagers on eight-to ten-metre class telescopes. Young stars rotate more rapidly and are more active than their older counterparts. Both effects can limit the ability to detect planets using RV. Aims. We wish to explore the planet detection abilities of a representative sample of stars in close and young associations with RV data and to explore the complementarity between this technique and direct imaging. Methods. We observed 26 such targets with spectral types from A to K and ages from 8 to 300 Myr with HARPS. We computed the detection limits with two methods, in particular, a method we have recently developed that takes the frequency distribution of the RV variations into account. We also attempted to improve the detection limits in a few cases by correcting for the stellar activity. Results. Our A-type stars RV show high-frequency variations due to pulsations, while our F-K stars clearly show activity with more or less complex patterns. For F-K stars, the RV jitter and v sin i rapidly decrease with star age. The data allow us to search for planets with periods typically ranging from 1 day to 100 days, and up to more than 500 days in a few cases. Within the present detection limits, no planet was found in our sample. For the bulk of our F-K stars, the detection limits fall to sub-Jupiter masses. We show that these limits can be significantly improved by correcting even partially for stellar activity, down to a few Neptune masses for the least active stars. The detection limits on A-type stars can be significantly improved, down to a few Jupiter-mass planets, provided an appropriate observing strategy. We finally show the tremendous potential of coupling RV and adaptive-optics deep imaging results. Conclusions. The RV technique allows the detection of planets lighter than Jupiter, reaching a few Neptune masses around young stars aged typically 30 Myr or more. Detection limits increase at younger ages, but (sub-)Jupiter mass planets are still detectable. In the next few years, using complementary techniques will allow a full exploration of the Jupiter-mass planets' content of many of these stars.

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Section: Comparison With Previous Surveyscontrasting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Planets around stars in young nearby associations

Lagrange

Meunier

Chauvin

et al. 2013

A&A

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“…Six others were already followed either at optical or NIR wavelengths, albeit at a 50 m s −1 precision (AGTri, ATMicA, ATMicB, auMic, BD+012447, V1005Ori; Paulson & Yelda 2006;Bailey et al 2012), and three targets benefited from a precise RV follow-up at optical wavelengths (BD+201790,εEridani, GJ3305AB; e.g., Campbell et al 1988;Figueira et al 2010;Elliott et al 2014;Hernán-Obispo et al 2015).…”

Section: The Young Samplementioning

confidence: 99%

A High-Precision Near-Infrared Survey for Radial Velocity Variable Low-Mass Stars Using Cshell and a Methane Gas Cell

Gagné

Plavchan

Gao

et al. 2016

ApJ

232

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We present the results of a precise near-infrared (NIR) radial velocity (RV) survey of 32 low-mass stars with spectral types K2-M4 using CSHELL at the NASA InfraRed Telescope Facility in the K band with an isotopologue methane gas cell to achieve wavelength calibration and a novel, iterative RV extraction method. We surveyed 14 members of young (≈25-150 Myr) moving groups, the young field star εEridani, and 18 nearby (<25 pc) low-mass stars and achieved typical single-measurement precisions of 8-15 m s −1 with a long-term stability of 15-50 m s −1 over longer baselines. We obtain the best NIR RV constraints to date on 27 targets in our sample, 19 of which were never followed by high-precision RV surveys. Our results indicate that very active stars can display long-term RV variations as low as ∼25-50 m s −1 at ≈2.3125 μm, thus constraining the effect of jitter at these wavelengths. We provide the first multiwavelength confirmation of GJ876bc and independently retrieve orbital parameters consistent with previous studies. We recovered RV variabilities for HD160934AB and GJ725AB that are consistent with their known binary orbits, and nine other targets are candidate RV variables with a statistical significance of 3σ-5σ. Our method, combined with the new iSHELL spectrograph, will yield long-term RV precisions of 5 m s −1 in the NIR, which will allow the detection of super-Earths near the habitable zone of mid-M dwarfs.

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“…Although bisector analysis may sometimes lead to the confirmation of a planet orbiting a star even when RV jitter is present (Sozzetti et al 2006;Setiawan et al 2007Setiawan et al , 2008, the latter technique is not always successful (Huélamo et al 2008;Figueira et al 2010). Several authors have studied the impact of activity on RV jitter using R HK as a proxy (Saar et al 1998;Santos et al 2000;Paulson et al 2002;Saar et al 2003;Wright 2005;Paulson & Yelda 2006;Santos et al 2010). In particular, Saar et al (1998) and Santos et al (2000) compiled empirical relationships between σ rv and R HK for stars in the Lick v r survey and the Geneva extrasolar planet search programme.…”

Section: Predicted Radial Velocity Jittermentioning

confidence: 99%

Chromospheric activity and rotation of FGK stars in the solar vicinity

Martínez-Arnáiz¹,

Maldonado

Montes³

et al. 2010

A&A

113

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Context. Chromospheric activity produces both photometric and spectroscopic variations that can be mistaken as planets. Large spots crossing the stellar disc can produce planet-like periodic variations in the light curve of a star. These spots clearly affect the spectral line profiles, and their perturbations alter the line centroids creating a radial velocity jitter that might "contaminate" the variations induced by a planet. Precise chromospheric activity measurements are needed to estimate the activity-induced noise that should be expected for a given star. Aims. We obtain precise chromospheric activity measurements and projected rotational velocities for nearby (d ≤ 25 pc) cool (spectral types F to K) stars, to estimate their expected activity-related jitter. As a complementary objective, we attempt to obtain relationships between fluxes in different activity indicator lines, that permit a transformation of traditional activity indicators, i.e., Ca ii H & K lines, to others that hold noteworthy advantages.Methods. We used high resolution (∼50 000) echelle optical spectra. Standard data reduction was performed using the IRAF echelle package. To determine the chromospheric emission of the stars in the sample, we used the spectral subtraction technique. We measured the equivalent widths of the chromospheric emission lines in the subtracted spectrum and transformed them into fluxes by applying empirical equivalent width and flux relationships. Rotational velocities were determined using the cross-correlation technique. To infer activity-related radial velocity (RV) jitter, we used empirical relationships between this jitter and the R HK index. Results. We measured chromospheric activity, as given by different indicators throughout the optical spectra, and projected rotational velocities for 371 nearby cool stars. We have built empirical relationships among the most important chromospheric emission lines. Finally, we used the measured chromospheric activity to estimate the expected RV jitter for the active stars in the sample.

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Differential Radial Velocities and Stellar Parameters of Nearby Young Stars

Cited by 77 publications

References 44 publications

Planets around stars in young nearby associations

Planets around stars in young nearby associations

A High-Precision Near-Infrared Survey for Radial Velocity Variable Low-Mass Stars Using Cshell and a Methane Gas Cell

Chromospheric activity and rotation of FGK stars in the solar vicinity

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