An Earth-sized planet with an Earth-like density

Pepe, F.; Cameron, A. Collier; Latham, David W.; Molinari, E.; Udry, S.; Bonomo, A. S.; Buchhave, Lars A.; Charbonneau, David; Cosentino, R.; Dressing, Courtney D.; Dumusque, X.; Figueira, P.; Fiorenzano, A. F. Martínez; Gettel, Sara; Harutyunyan, A.; Haywood, R. D.; Horne, K.; López‐Morales, Mercedes; Lovis, C.; Malavolta, L.; Mayor, M.; Micela, G.; Motalebi, F.; Nascimbeni, V.; Phillips, David F.; Piotto, G.; Pollacco, D.; Queloz, D.; Rice, Ken; Sasselov, Dimitar; Ségransan, D.; Sozzetti, A.; Szentgyorgyi, Andrew; Watson, C. A.

doi:10.1038/nature12768

Cited by 220 publications

(163 citation statements)

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“…Second and perhaps more importantly, the RV signal induced by stellar spots is expected to have an ≈λ −1 dependence for modest spot contrast temperatures, where λ is the wavelength (Reiners et al 2010;Anglada-Escudé et al 2012;Howard et al 2013;Pepe et al 2013;Marchwinski et al 2015;Plavchan et al 2015), which means that the effect of stellar spots on NIR RV measurements is less important than it is at visible wavelengths by a factor ∼4. However, there have also been predictions that the Zeeman effect resulting from the strong magnetic activity in young stars could cause jitter to increase as a function of wavelength (Reiners et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…The method of Doppler radial velocity (RV) variations has proven itself fruitful in the last decades both for the identification of new exoplanets (e.g., Mayor & Queloz 1995;Marcy et al 1998Marcy et al , 2001Delfosse et al 1998a;Cochran et al 2002;Endl et al 2003;Butler et al 2004;Rivera et al 2005bRivera et al , 2010Meschiari et al 2011;Dumusque et al 2012;Montet et al 2014;Tuomi et al 2014) and for the confirmation of exoplanets detected by the method of transit (e.g., Kepler-78b; Akeson et al 2013;Pepe et al 2013;Sanchis-Ojeda et al 2013). Recent developments have shown that cool (3800 K) stellar hosts in the M spectral class represent valuable targets for the identification of new Earthmass planetary companions in the habitable zone using the RV method due to their smaller mass and significantly larger population (Henry et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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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“…In this work we combine Kepler photometry with highprecision radial-velocity measurements of the Kepler-101 twoplanet system gathered in the context of the GTO program of the HARPS-N Consortium (Pepe et al 2013;Dumusque et al 2014). Kepler-101 was initially identified as Kepler object of interest 46 (KOI-46).…”

Section: Introductionmentioning

confidence: 99%

Characterization of the planetary system Kepler-101 with HARPS-N

Bonomo

Sozzetti

Lovis

et al. 2014

A&A

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We characterize the planetary system Kepler-101 by performing a combined differential evolution Markov chain Monte Carlo analysis of Kepler data and forty radial velocities obtained with the HARPS-N spectrograph. This system was previously validated and is composed of a hot super-Neptune, Kepler-101b, and an Earth-sized planet, Kepler-101c. These two planets orbit the slightly evolved and metal-rich G-type star in 3.49 and 6.03 days, respectively. With mass M p = 51.1 +5.1 −4.7 M ⊕ , radius R p = 5.77 +0.85 −0.79 R ⊕ , and density ρ p = 1.45 +0.83 −0.48 g cm −3 , Kepler-101b is the first fully characterized super-Neptune, and its density suggests that heavy elements make up a significant fraction of its interior; more than 60% of its total mass. Kepler-101c has a radius of 1.25 +0.19 −0.17 R ⊕ , which implies the absence of any H/He envelope, but its mass could not be determined because of the relative faintness of the parent star for highly precise radial-velocity measurements (K p = 13.8) and the limited number of radial velocities. The 1σ upper limit, M p < 3.8 M ⊕ , excludes a pure iron composition with a probability of 68.3%. The architecture of the planetary system Kepler-101 − containing a close-in giant planet and an outer Earth-sized planet with a period ratio slightly larger than the 3:2 resonance − is certainly of interest for scenarios of planet formation and evolution. This system does not follow the previously reported trend that the larger planet has the longer period in the majority of Kepler systems of planet pairs with at least one Neptune-sized or larger planet.

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“…Only five other USPs have measured masses and densities: 55 Cnc (Fischer et al 2008;Dawson & Fabrycky 2010;Nelson et al 2014;Demory et al 2016), CoRoT-7b (Léger et al 2009;Bruntt et al 2010;Haywood et al 2014), Kepler-10b Esteves et al 2015), Kepler-78b (Howard et al 2013;Pepe et al 2013;Grunblatt et al 2015), and WASP-47e Dai et al 2015;Sinukoff et al 2017). These planets are plotted on the mass-radius diagram in Figure 7(b).…”

Section: Ultra-short-period Planetsmentioning

confidence: 99%

K2-66b and K2-106b: Two Extremely Hot Sub-Neptune-size Planets with High Densities

Sinukoff

Howard

Petigura

et al. 2017

Self Cite

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We report precise mass and density measurements of two extremely hot sub-Neptune-size planets from the K2 mission using radial velocities, K2 photometry, and adaptive optics imaging. K2-66 harbors a close-in subNeptune-sized ( -+ 2.49 0.24 0.34 Å R ) planet (K2-66b) with a mass of  21.3 3.6 Å M . Because the star is evolving up the subgiant branch, K2-66b receives a high level of irradiation, roughly twice the main-sequence value. K2-66b may reside within the so-called "photoevaporation desert," a domain of planet size and incident flux that is almost completely devoid of planets. Its mass and radius imply that K2-66b has, at most, a meager envelope fraction (<5%) and perhaps no envelope at all, making it one of the largest planets without a significant envelope. K2-106 hosts an ultra-short-period planet (P=13.7 hr) that is one of the hottest sub-Neptune-size planets discovered to date. Its radius ( -+ 1.82 0.14 0.20 Å R ) and mass (  9.0 1.6 Å M ) are consistent with a rocky composition, as are all other small ultra-short-period planets with well-measured masses. K2-106 also hosts a larger, longer-period planet (R p = -+ 2.77 0.23 0.37 Å R , P=13.3 days) with a mass less than 24.4 Å M at 99.7% confidence. K2-66b and K2-106b probe planetary physics in extreme radiation environments. Their high densities reflect the challenge of retaining a substantial gas envelope in such extreme environments.

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An Earth-sized planet with an Earth-like density

Cited by 220 publications

References 27 publications

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

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

Characterization of the planetary system Kepler-101 with HARPS-N

K2-66b and K2-106b: Two Extremely Hot Sub-Neptune-size Planets with High Densities

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