Three Small Super-Earths Transiting the nearby star GJ 9827

TL;DR

This paper reports the discovery of three transiting super-Earths around the nearby star GJ 9827, with detailed characterization suggesting they are prime candidates for atmospheric study and understanding planetary composition thresholds.

Contribution

The discovery of three small transiting planets around GJ 9827, including their detailed radii, periods, and potential for atmospheric observation, is a novel addition to exoplanet research.

Findings

Planets have radii of 1.36-2.10 R⊕ and periods of 1.2-6.2 days.

Planets are near 1:3:5 mean motion resonance.

System offers insights into rocky vs gaseous planetary thresholds.

Abstract

We report on the discovery of three transiting planets around GJ~9827. The planets have radii of 1.75$_{-0.12}^{+0.11 }$, 1.36$_{- 0.09 }^{+ 0.09}$, and 2.10$_{- 0.15 }^{+ 0.15 }$~R$_{\oplus}$, and periods of 1.20896, 3.6480, and 6.2014 days, respectively. The detection was made in Campaign 12 observations as part of our K2 survey of nearby stars. GJ~9827 is a $V = 10.39$~mag K6V star at distance of 30.3 parsecs and the nearest star to be found hosting planets by Kepler and K2. The radial velocity follow-up, high resolution imaging, and detection of multiple transiting objects near commensurability drastically reduce the false positive probability. The orbital periods of GJ~9827~b, c and d planets are very close to the 1:3:5 mean motion resonance. Our preliminary analysis shows that GJ~9827 planets are excellent candidates for atmospheric observations. Besides, the planetary radii span both sides of the rocky and gaseous divide, hence the system will be an asset in expanding our understanding of the threshold.