LBT Reveals Large Dust Particles and a High Mass Loss Rate for K2-22 b

Abstract

The disintegrating planet candidate K2-22 b shows periodic and stochastic transits best explained by an escaping debris cloud. However, the mechanism that creates the debris cloud is unknown. The grain size of the debris as well as its sublimation rate can be helpful in understanding the environment that disintegrates the planet. Here, we present simultaneous photometry with the g band at 0.48 microns and KS band at 2.1 microns using the Large Binocular Telescope. During an event with very low dust activity, we put a new upper limit on the size of the planet of 0.71 earth radii or 4500 km. We also detected a medium-depth transit which can be used to constrain the dust particle sizes. We find that the median particle size must be larger than about 0.5 to 1.0 microns, depending on the composition of the debris. This leads to a high mass loss rate of about 3e8 kg/s that is consistent with hydrodynamic escape models. If they are produced by some alternate mechanism such as explosive volcanism, it would require extraordinary geological activity. Combining our upper limits on the planet size with the high mass loss rate, we find a lifetime of the planet of less than 370 Myr. This drops to just 21 Myr when adopting the 0.02 earth masses predicted from hydrodynamical models.

AJ, accepted, 13 pages

References in corpus (12)

• The NumPy array: a structure for efficient numerical computation
• Mass-Radius Relationships for Solid Exoplanets
• The performance of the blue prime focus Large Binocular Camera at the Large Binocular Telescope
• Searching the Entirety of Kepler Data. II. Occurrence Rate Estimates for FGK Stars
• Coreless Terrestrial Exoplanets
• Multiwavelength Observations of the Candidate Disintegrating sub-Mercury KIC 12557548b
• Dusty tails of evaporating exoplanets. I. Constraints on the dust composition
• WD 1145+017 Photometric Observations During 8 Months of High Activity
• Direct evidence for an evolving dust cloud from the exoplanet KIC 12557548 b
• The Relation between the Transit Depths of KIC 12557548b & the Stellar Rotation Period
• Dusty tails of evaporating exoplanets. II. Physical modelling of the KIC 12557548b light curve
• Constraining the Bulk Composition of Disintegrating Exoplanets Using Combined Transmission Spectra from JWST and SPICA

Cited by in corpus (4)

• Dust formation in the outflows of catastrophically evaporating planets
• Chaotic winds from a dying world: a one-dimensional map for evolving atmospheres
• A Disintegrating Rocky World Shrouded in Dust and Gas: Mid-IR Observations of K2-22b using JWST
• Climate Change in Hell: Long-Term Variation in Transits of the Evaporating Planet K2-22b