Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune

Barragán, Oscar; Aigrain, S.; Kubyshkina, Daria; Gandolfi, D.; Livingston, John H.; Fridlund, M.; Fossati, L.; Korth, J.; Parviainen, H.; Malavolta, L.; Πάλλη, Ε.; Deeg, H. J.; Nowak, G.; Rajpaul, Vinesh; Zicher, N.; Antoniciello, G.; Narita, Norio; Albrecht, S.; Bedin, L. R.; Cabrera, J.; Cochran, William D.; Leon, Jerome de; Eigmüller, Philipp; Fukui, A.; Granata, V.; Grziwa, S.; Guenther, E. W.; Hatzes, A. P.; Kusakabe, Nobuhiko; Latham, David W.; Libralato, Mattia; Luque, R.; Montañés-Rodŕıguez, P.; Murgas, F.; Nardiello, D.; Pagano, I.; Piotto, G.; Persson, C. M.; Redfield, Seth; Tamura, Motohide

doi:10.1093/mnras/stz2569

Cited by 69 publications

(92 citation statements)

References 73 publications

(77 reference statements)

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“…3. Our results are broadly consistent with the most recent lightcurve analysis from Barragán et al (2019). This includes a preference for low or zero orbital eccentricity (e < 0.15 with 90% confidence, and e < 0.28 at 99% confidence) compared to earlier analysis lacking short-cadence K2 data that suggested a non-zero orbital eccentricity (e = 0.28± 0.19 0.12 Mann et al 2017a).…”

Section: Transit Lightcurve and Orbitsupporting

confidence: 91%

“…The Campaign 5 observations were used to identify the planet, and are described in more detail in the discovery paper (Mann et al 2017a). The Campaign 18 short-cadence observations were proposed to improve the parameters of K2-100b and search for long-period planets (GO18006, GO18023, GO18027, and GO18036), and were described previously in Barragán et al (2019).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…The other three used the MuSCAT2 multi-bandpass photometer installed in the Carlos Sanchez Telescope (TCS) in the Teide observatory. The diffuser transit observations are described in Stefansson et al (2018), while the MuSCAT2 observations are described in Barragán et al (2019). For all data, we used the provided light curve for our MCMC analysis, only normalizing the out-of-transit baseline and updating the uncertainties based on the estimates in Barragán et al (2019).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…By analyzing time-series of spectroscopic activity signals, Barragán et al (2019) refined the rotation period of K2-100 to 4.315 days. The star lies within the locus of Praesepe stars in a period-color diagram (Fig.…”

Section: Stellar Rotationmentioning

confidence: 99%

“…K2-100b's host star is highly rotationally variable, challenging both transit and RV measurements. Barragán et al (2019) used a Gaussian process-regression of RV measurements with spectroscopic indicators of stellar activity to infer a mass of 22 ± 6M ⊕ , i.e. at 3σ significance.…”

Section: Introductionmentioning

confidence: 99%

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Zodiacal exoplanets in time – X. The orbit and atmosphere of the young ‘neptune desert’-dwelling planet K2-100b

Gaidos

Hirano

Mann

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We obtained high-resolution infrared spectroscopy and short-cadence photometry of the 600-800 Myr Praesepe star K2-100 during transits of its 1.67-day planet. This Neptune-size object, discovered by the NASA K2 mission, is an interloper in the "desert" of planets with similar radii on short period orbits. Our observations can be used to understand its origin and evolution by constraining the orbital eccentricity by transit fitting, measuring the spin-orbit obliquity by the Rossiter-McLaughlin effect, and detecting any extended, escaping hydrogen-helium envelope with the 10830Å line of neutral helium in the 2s 3 S triplet state. Transit photometry with 1-min cadence was obtained by the K2 satellite during Campaign 18 and transit spectra were obtained with the IRD spectrograph on the Subaru telescope. While the elevated activity of K2-100 prevented us from detecting the Rossiter-McLaughlin effect, the new photometry combined with revised stellar parameters allowed us to constrain the eccentricity to e < 0.15/0.28 with 90%/99% confidence. We modeled atmospheric escape as an isothermal, spherically symmetric Parker wind, with photochemistry driven by UV radiation that we estimate by combining the observed spectrum of the active Sun with calibrations from observations of K2-100 and similar young stars in the nearby Hyades cluster. Our non-detection (< 5.7mÅ) of a transit-associated He I line limits mass loss of a solar-composition atmosphere through a T ≤ 10000K wind to < 0.3 M ⊕ Gyr −1 . Either K2-100b is an exceptional desert-dwelling planet, or its mass loss is occurring at a lower rate over a longer interval, consistent with a core accretion-powered scenario for escape.

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Section: Transit Lightcurve and Orbitsupporting

confidence: 91%

Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Stellar Rotationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Zodiacal exoplanets in time – X. The orbit and atmosphere of the young ‘neptune desert’-dwelling planet K2-100b

Gaidos

Hirano

Mann

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Observations of planetary winds and outflows

Santos

2021

Proc. IAU

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We have recently hit the milestone of 5,000 exoplanets discovered. In stark contrast with the Solar System, most of the exoplanets we know to date orbit extremely close to their host stars, causing them to lose copious amounts of gas through atmospheric escape at some stage in their lives. In some planets, this process can be so dramatic that they shrink in timescales of a few million to billions of years, imprinting features in the demographics of transiting exoplanets. Depending on the transit geometry, ionizing conditions, and atmospheric properties, a planetary outflow can be observed using transmission spectroscopy in the ultraviolet, optical or near-infrared. In this review, we will discuss the main techniques to observe evaporating exoplanets and their results. To date, we have evidence that at least 28 exoplanets are currently losing their atmospheres, and the literature has reported at least 42 non-detections.

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A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system

et al. 2022

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OI-500 (also known as HIP 34269, TIC 134200185 and CD-47 2804) is a high-proper-motion star (Table 1) with a radial velocity of 55.6 km s −1 (ref. 1 ) and a V-band magnitude of 10. 54 (ref. 2 ) located at a distance of 47.39 pc from the Sun 1 . The National Aeronautics and Space Administration's (NASA's) Transiting Exoplanet Survey Satellite 3 (TESS) observed TOI-500 for the first time in sectors 6, 7 and 8 between 11 December 2018 and 28 February 2019. The TESS Science Processing Operations Center 4 (SPOC) identified the signature of a possible Earth-sized transiting planet with an orbital period of nearly 13 hours. The candidate was subsequently designated as TOI-500.01 by the TESS Science Office and announced on 8 March 2019. We performed an independent analysis of the TESS light curves with the codes Détection Spécialisée de Transits 5 and Transit Least Square 6 , which confirmed the presence of the candidate (Fig. 1) and excluded additional significant transit signals. We used the Las Cumbres Observatory Global Telescope 7 (LCOGT) to perform photometric observations of the 78 neighbouring stars up to about Δmag ≈ 10 at angular separation between 12″ and 2.5′ from TOI-500 (Extended Data Fig. 1). The analysis of the retrieved light curves allowed us to exclude that those sources are contaminating eclipsing binaries mimicking the transit signal detected in the TESS light curves. Speckle images acquired with the 4.1 m Southern Astrophysical Research (SOAR) telescope (Cerro Tololo Inter-American Observatory, Chile) and the 8.1 m Gemini South telescope (Cerro Pachón, Chile) excluded the presence of nearby stars up to about Δmag ≈ 7, as close as 0.02″ (Zorro@Gemini speckle inner working angle; Extended Data Fig. 2) and out to 3″ (SOAR outer limit; Extended Data Fig. 3). Finally, we confirmed the planetary nature of the transit signal with an intensive radial velocity (RV) follow-up campaign carried out with the High-Accuracy Radial Velocity Planet Searcher 8 (HARPS) spectrograph mounted at the 3.6 m telescope of the European Southern Observatory (ESO, La Silla, Chile). We collected nearly 200 HARPS spectra of TOI-500 between 22 March 2019 and 23 March 2020. Our RV measurements also unveiled the presence of three additional Doppler signals that have no counterpart in any of the stellar activity indicators, providing strong evidence that they are induced by three additional planets . TOI-500 is thus orbited by (at least) four planets, three of which are not seen to transit their host star. To determine the planetary parameters, we

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Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune

Cited by 69 publications

References 73 publications

Zodiacal exoplanets in time – X. The orbit and atmosphere of the young ‘neptune desert’-dwelling planet K2-100b

Zodiacal exoplanets in time – X. The orbit and atmosphere of the young ‘neptune desert’-dwelling planet K2-100b

Observations of planetary winds and outflows

A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system

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