Using HARPS-N to characterize the long-period planets in the PH-2 and Kepler-103 systems

Dubber, Sophie; Mortier, A.; Rice, Ken; Nava, Chantanelle; Malavolta, L.; Giles, H.; Coffinet, A.; Charbonneau, David; Vanderburg, Andrew; Bonomo, A. S.; Boschin, W.; Buchhave, Lars A.; Cameron, A. Collier; Cosentino, R.; Dumusque, X.; Ghedina, A.; Harutyunyan, A.; Haywood, R. D.; Latham, David W.; López‐Morales, Mercedes; Micela, G.; Molinari, E.; Pepe, F.; Phillips, David F.; Piotto, G.; Poretti, E.; Sasselov, Dimitar; Sozzetti, A.; Udry, S.

doi:10.1093/mnras/stz2856

Cited by 15 publications

(13 citation statements)

References 92 publications

(121 reference statements)

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“…The prior PDF of the periodic coherence scale (γ) was uniform between 0.05 and 5. The typical value for γ in the literature is thought to be 0.5 (Dubber et al 2019). This prior is designed to explore one order of magnitude below and above this typical values.…”

Section: Appendix A2: Stellar Modeling: Mass Radius and Agementioning

confidence: 99%

Warm terrestrial planet with half the mass of Venus transiting a nearby star

Demangeon

Osorio

Alibert

et al. 2021

A&A

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In recent years, the advent of a new generation of radial velocity instruments has allowed us to detect planets with increasingly lower mass and to break the one Earth-mass barrier. Here we report a new milestone in this context by announcing the detection of the lowest-mass planet measured so far using radial velocities: L 98-59 b, a rocky planet with half the mass of Venus. It is part of a system composed of three known transiting terrestrial planets (planets b–d). We announce the discovery of a fourth nontransiting planet with a minimum mass of 3.06−0.37+0.33 M⊕ and an orbital period of 12.796−0.019+0.020 days and report indications for the presence of a fifth nontransiting terrestrial planet. With a minimum mass of 2.46−0.82+0.66 M⊕ and an orbital period 23.15−0.17+0.60 days, this planet, if confirmed, would sit in the middle of the habitable zone of the L 98-59 system. L 98-59 is a bright M dwarf located 10.6ṗc away. Positioned at the border of the continuous viewing zone of the James Webb Space Telescope, this system is destined to become a corner stone for comparative exoplanetology of terrestrial planets. The three transiting planets have transmission spectrum metrics ranging from 49 to 255, which undoubtedly makes them prime targets for an atmospheric characterization with the James Webb Space Telescope, the Hubble Space Telescope, Ariel, or ground-based facilities such as NIRPS or ESPRESSO. With an equilibrium temperature ranging from 416 to 627 K, they offer a unique opportunity to study the diversity of warm terrestrial planets without the unknowns associated with different host stars. L 98-59 b and c have densities of 3.6−1.5+1.4 and 4.57−0.85+0.77 g cm−3, respectively, and have very similar bulk compositions with a small iron core that represents only 12 to 14% of the total mass, and a small amount of water. However, with a density of 2.95−0.51+0.79 g cm−3 and despite a similar core mass fraction, up to 30% of the mass of L 98-59 d might be water.

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Section: Appendix A2: Stellar Modeling: Mass Radius and Agementioning

confidence: 99%

Warm terrestrial planet with half the mass of Venus transiting a nearby star

Demangeon

Osorio

Alibert

et al. 2021

A&A

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“…We used a quasi-periodic covariance kernel (as described in e.g. Grunblatt et al 2015;Dubber et al 2019) and allowed for additional white noise. The PyORBIT code ) was used to do the analysis and MultiNest was used for the parameter inference, with 400 live points.…”

Section: From Photometrymentioning

confidence: 99%

“…We constrained the rotation period to be lower than 100 d, the decay timescale to be lower than 1000 d, and the coherence scale to be between 0.2 and 2.0, shown by several works (e.g. Haywood et al 2014;Dubber et al 2019) to be the most physically motivated for stellar activity phenomena 8 . Taking the median, 16th and 84th percentile of the posterior distributions, the results are as follows: rotation period rot = 27.4 +1.4 −1.2 d, decay timescale dec = 83 +255 −51 d, amplitude ℎ = 1.2 ± 0.3 ppt, coherence scale = 0.32 +0.32 −0.09 , and white noise = 1.2 ± 0.2 ppt.…”

Section: From Photometrymentioning

confidence: 99%

K2-111: an old system with two planets in near-resonance†

Mortier

Osorio

Malavolta

et al. 2020

Monthly Notices of the Royal Astronomical Society

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This paper reports on the detailed characterisation of the K2-111 planetary system with K2, WASP, and ASAS-SN photometry as well as high-resolution spectroscopic data from HARPS-N and ESPRESSO. The host, K2-111, is confirmed to be a mildly evolved (log g = 4.17), iron-poor ([Fe/H]=−0.46), but alpha-enhanced ([α/Fe]=0.27), chromospherically quiet, very old thick disc G2 star. A global fit, performed by using PyORBIT shows that the transiting planet, K2-111 b, orbits with a period Pb = 5.3518 ± 0.0004 d, and has a planet radius of $1.82^{+0.11}_{-0.09}$ R⊕ and a mass of $5.29^{+0.76}_{-0.77}$ M⊕, resulting in a bulk density slightly lower than that of the Earth. The stellar chemical composition and the planet properties are consistent with K2-111 b being a terrestrial planet with an iron core mass fraction lower than the Earth. We announce the existence of a second signal in the radial velocity data that we attribute to a non-transiting planet, K2-111 c, with an orbital period of 15.6785 ± 0.0064 days, orbiting in near-3:1 mean-motion resonance with the transiting planet, and a minimum planet mass of 11.3 ± 1.1 M⊕. Both planet signals are independently detected in the HARPS-N and ESPRESSO data when fitted separately. There are potentially more planets in this resonant system, but more well-sampled data are required to confirm their presence and physical parameters.

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“…However, at orbital periods up to 400 days, suspected giant planet transit signals have an alarmingly high false positive probability (e.g., Santerne et al 2016). Therefore, mass measurement is needed when confirming the planetary nature of a long-period (P 100 days), giant exoplanet (e.g., Dubber et al 2019).…”

Section: Confirming Kepler-1514 Bmentioning

confidence: 99%

“…Yet, planetary confirmation through mass measurement is especially critical for giant planet candidates with P 100 days that have been found to have a false-positive rate greater than 50% in transit surveys (Santerne et al 2016). However, since longperiod orbits require long-duration follow-up campaigns, the number of long-period exoplanets with precise mass and radius is further limited (e.g., Dubber et al 2019).…”

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confidence: 99%

Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. I. Confirmation of an Eccentric, Cool Jupiter With an Interior Earth-sized Planet Orbiting Kepler-1514

Dalba,

Kane,

Isaacson

et al. 2020

Preprint

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Despite the severe bias of the transit method of exoplanet discovery toward short orbital periods, a modest sample of transiting exoplanets with orbital periods greater than 100 days is known. Long-term radial velocity (RV) surveys are pivotal to confirming these signals and generating a set of planetary masses and densities for planets receiving moderate to low irradiation from their host stars. Here, we conduct RV observations of Kepler-1514 from the Keck I telescope using the High Resolution Echelle Spectrometer. From these data, we measure the mass of the statistically validated giant (1.108 ± 0.023 R J ) exoplanet Kepler-1514 b with a 218 day orbital period as 5.28 ± 0.22 M J . The bulk density of this cool (∼390 K) giant planet is 4.82 +0.26 −0.25 g cm −3 , consistent with a core supported by electron degeneracy pressure. We also infer an orbital eccentricity of 0.401 +0.013 −0.014 from the RV and transit observations, which is consistent with planet-planet scattering models. The Kepler-1514 system contains an Earth-size, Kepler Object of Interest on a 10.5 day orbit that we statistically validate against false positive scenarios, including those involving a neighboring star. The combination of the brightness (V =11.8) of the host star and the long period, low irradiation, and high density of Kepler-1514 b places this system among a rare group of known exoplanetary systems and one that is amenable to continued study.

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Using HARPS-N to characterize the long-period planets in the PH-2 and Kepler-103 systems

Cited by 15 publications

References 92 publications

Warm terrestrial planet with half the mass of Venus transiting a nearby star

Warm terrestrial planet with half the mass of Venus transiting a nearby star

K2-111: an old system with two planets in near-resonance†

Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. I. Confirmation of an Eccentric, Cool Jupiter With an Interior Earth-sized Planet Orbiting Kepler-1514

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