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In an effort to measure the masses of planets discovered by the NASA {it K2} mission, we have conducted precise Doppler observations of five stars with transiting planets. We present the results of a joint analysis of these new data and previously published Doppler data. The first star, an M dwarf known as K2-3 or EPIC~201367065, has three transiting planets (b, with radius $2.1~R_{oplus}$; c, $1.7~R_{oplus}$; and d, $1.5~R_{oplus}$). Our analysis leads to the mass constraints: $M_{b}=8.1^{+2.0}_{-1.9}~M_{oplus}$ and $M_{c}$ < $ 4.2~M_{oplus}$~(95%~conf.). The mass of planet d is poorly constrained because its orbital period is close to the stellar rotation period, making it difficult to disentangle the planetary signal from spurious Doppler shifts due to stellar activity. The second star, a G dwarf known as K2-19 or EPIC~201505350, has two planets (b, $7.7~R_{oplus}$; and c, $4.9~R_{oplus}$) in a 3:2 mean-motion resonance, as well as a shorter-period planet (d, $1.1~R_{oplus}$). We find $M_{b}$= $28.5^{+5.4}_{-5.0} ~M_{oplus}$, $M_{c}$= $25.6^{+7.1}_{-7.1} ~M_{oplus}$ and $M_{d}$ < $14.0~M_{oplus} $~(95%~conf.). The third star, a G dwarf known as K2-24 or EPIC~203771098, hosts two transiting planets (b, $5.7~R_{oplus}$; and c, $7.8~R_{oplus}$) with orbital periods in a nearly 2:1 ratio. We find $M_{b}$= $19.8^{+4.5}_{-4.4} ~M_{oplus}$ and $M_{c}$ = $26.0^{+5.8}_{-6.1}~M_{oplus}$.....
We analyzed the photometry of 20038 cool stars from campaigns 12, 13, 14 and 15 of the K2 mission in order to detect, characterize and validate new planetary candidates transiting low-mass stars. We present a catalogue of 25 new periodic transit-like
The Kepler extended mission, also known as K2, has provided the community with a wealth of planetary candidates that orbit stars typically much brighter than the targets of the original mission. These planet candidates are suitable for further spectr
We report the first results from a search for transiting warm Jupiter exoplanets - gas giant planets receiving stellar irradiation below about $10^8$ erg s$^{-1}$ cm$^{-2}$, equivalent to orbital periods beyond about 10 days around Sun-like stars. We
We revisit the discovery and implications of the first candidate systems to contain multiple transiting exoplanets. These systems were discovered using data from the Kepler space telescope. The initial paper, presenting five systems (Steffen et al. 2
We recently used near-infrared spectroscopy to improve the characterization of 76 low-mass stars around which K2 had detected 79 candidate transiting planets. Thirty of these worlds were new discoveries that have not previously been published. We cal