The GJ1214 Super-Earth System: Stellar Variability, New Transits, and a Search for Additional Planets

TL;DR

This study refines the physical properties of the GJ1214b super-Earth and its host star through new transit observations, stellar variability analysis, and a search for additional planets, demonstrating low stellar activity and constraining potential companions.

Contribution

The paper provides new high-precision transit data, analyzes stellar variability over three years, and sets limits on additional planets in the GJ1214 system, improving understanding of the system's characteristics.

Findings

Stellar rotation period likely an integer multiple of 53 days.

Stellar variability is low, not significantly affecting atmospheric studies.

No additional transiting planets detected within the habitable zone.

Abstract

The super-Earth GJ1214b transits a nearby M dwarf that exhibits 1% intrinsic variability in the near-infrared. Here, we analyze new observations to refine the physical properties of both the star and planet. We present three years of out-of-transit photometric monitoring of the stellar host GJ1214 from the MEarth Observatory and find the rotation period to be long, mostly likely an integer multiple of 53 days, suggesting low levels of magnetic activity and an old age for the system. We show such variability will not pose significant problems to ongoing studies of the planet's atmosphere with transmission spectroscopy. We analyze 2 high-precision transit light curves from ESO's Very Large Telescope along with 7 others from the MEarth and FLWO 1.2 meter telescopes, finding physical parameters for the planet that are consistent with previous work. The VLT light curves show tentative evidence for spot occultations during transit. Using two years of MEarth light curves, we place limits on additional transiting planets around GJ1214 with periods out to the habitable zone of the system. We also improve upon the previous photographic V -band estimate for the star, finding V = 14.71 \pm 0.03.