|
Description
We report the discovery of a Neptune-like planet (LP714-47b, P=4.05204d, m=30.8+/-1.5 M_Earth_, r=4.7+/-0.3 R_Earth_) located in the 'hot Neptune desert'. Confirmation of the TESS Object of Interest (TOI 442.01) was achieved with radial-velocity follow-up using CARMENES, ESPRESSO, HIRES, iSHELL, and PFS, as well as from photometric data using TESS, Spitzer, and ground-based photometry from MuSCAT2, TRAPPIST-South, MONET-South, the George Mason University telescope, the Las Cumbres Observatory Global Telescope network, the El Sauce telescope, the TUBITAK National Observatory, the University of Louisville Manner Telescope, and WASP-South. We also present high-spatial resolution adaptive optics imaging with the Gemini Near-Infrared Imager. The low uncertainties in the mass and radius determination place LP714-47b among physically well-characterised planets, allowing for a meaningful comparison with planet structure models. The host star LP714-47 is a slowly rotating early M dwarf (T_eff_=3950+/-51K) with a mass of 0.59+/-0.02M_{sun}_ and a radius of 0.58+/-0.02R_{sun}_. From long-term photometric monitoring and spectroscopic activity indicators, we determine a stellar rotation period of about 33d. The stellar activity is also manifested as correlated noise in the radial-velocity data. In the power spectrum of the radial-velocity data, we detect a second signal with a period of 16 days in addition to the four-day signal of the planet. This could be shown to be a harmonic of the stellar rotation period or the signal of a second planet. It may be possible to tell the difference once more TESS data and radial-velocity data are obtained.
|
