The Compositional Diversity of Low-Mass Exoplanets

Jontof-Hutter, Daniel

doi:10.1146/annurev-earth-053018-060352

Cited by 49 publications

(20 citation statements)

References 138 publications

(190 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Its period and radius place it below the gap in the distribution of close-in planetary radii around M dwarfs (Cloutier & Menou 2019), a gap that is at a slightly smaller radius range than for planets orbiting Sun-like stars (Fulton et al 2017;Cloutier & Menou 2019). It was shown by several authors that the majority of small planets, below the radius gap, with measured radii and masses have terrestrial bulk compositions (Dai et al 2019;Jontof-Hutter 2019;Otegi et al 2019). This prediction is consistent with GJ1252b's measured bulk density, of 6.8±2.2 g cm −3 , and its position between theoretical radiusmass relations assuming pure iron and pure rock compositions (Zeng et al 2016).…”

Section: Discussionmentioning

confidence: 99%

GJ 1252 b: A 1.2 R_⊕ Planet Transiting an M3 Dwarf at 20.4 pc

Shporer

Collins

Astudillo-Defru

et al. 2020

ApJL

View full text Add to dashboard Cite

We report the discovery of GJ1252b, a planet with a radius of 1.193±0.074 Å R and an orbital period of 0.52days around an M3-type star (0.381±0.019  M , 0.391±0.020  R ) located 20.385±0.019 pc away. We use Transiting Exoplanet Survey Satellite (TESS) data, ground-based photometry and spectroscopy, Gaia astrometry, and high angular resolution imaging to show that the transit signal seen in the TESS data must originate from a transiting planet. We do so by ruling out all false-positive scenarios that attempt to explain the transit signal as originating from an eclipsing stellar binary. Precise Doppler monitoring also leads to a tentative mass measurement of 2.09±0.56M ⊕ . The host star proximity, brightness (V=12.19 mag, K=7.92 mag), low stellar activity, and the system's short orbital period make this planet an attractive target for detailed characterization, including precise mass measurement, looking for other objects in the system, and planet atmosphere characterization.Unified Astronomy Thesaurus concepts: Exoplanet astronomy (486); M dwarf stars (982); Exoplanets (498)

show abstract

Section: Discussionmentioning

confidence: 99%

GJ 1252 b: A 1.2 R_⊕ Planet Transiting an M3 Dwarf at 20.4 pc

Shporer

Collins

Astudillo-Defru

et al. 2020

ApJL

View full text Add to dashboard Cite

show abstract

“…The properties of these planets and their host stars are summarized in Table 1. We note that different authors have differing definitions for this class of planets, with some adopting a strict boundary of M p < 10M ⊕ (e.g., Lee 2019;Jontof-Hutter 2019). Here we take the slightly more liberal approach of including planets with M p 15 M ⊕ , which includes the low-density planets Kepler-18d (Cochran et al 2011) and Kepler-177c (Vissapragada et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

Piro

Vissapragada

2020

View full text Add to dashboard Cite

An intriguing, growing class of planets are the "super-puffs," objects with exceptionally large radii for their masses and thus correspondingly low densities ( 0.3 g cm −3 ). Here we consider whether they could have large inferred radii because they are in fact ringed. This would naturally explain why super-puffs have thus far only shown featureless transit spectra. We find that this hypothesis can work in some cases but not all. The close proximity of the super-puffs to their parent stars necessitates rings with a rocky rather than icy composition. This limits the radius of the rings, and makes it challenging to explain the large size of Kepler 51b, 51c, 51d, and 79d unless the rings are composed of porous material. Furthermore, the short tidal locking timescales for Kepler 18d, 223d, and 223e mean that these planets may be spinning too slowly, resulting in a small oblateness and rings that are warped by their parent star. Kepler 87c and 177c have the best chance of being explained by rings. Using transit simulations, we show that testing this hypothesis requires photometry with a precision of somewhere between ∼ 10 ppm and ∼ 50 ppm, which roughly scales with the ratio of the planet and star's radii. We conclude with a note about the recently discovered super-puff HIP 41378f.

show abstract

“…(e.g., Jontof-Hutter et al 2015Jontof-Hutter 2019). To sample the posteriors of these parameters, we used a Differential Evolution Markov Chain Monte Carlo algorithm(Braak 2006;Jontof-Hutter et al 2015, beginning the…”

mentioning

confidence: 99%

A Featureless Infrared Transmission Spectrum for the Super-puff Planet Kepler-79d

Chachan

Jontof-Hutter

Knutson

et al. 2020

Self Cite

View full text Add to dashboard Cite

Extremely low-density planets ("super-puffs") are a small but intriguing subset of the transiting planet population. With masses in the super-Earth range (1 − 10 Å M) and radii akin to those of giant planets (> 4 Å R), their large envelopes may have been accreted beyond the water snow line and many appear to be susceptible to catastrophic mass loss. Both the presence of water and the importance of mass loss can be explored using transmission spectroscopy. Here, we present new Hubble space telescope WFC3 spectroscopy and updated Kepler transit depth measurements for the super-puff Kepler-79d. We do not detect any molecular absorption features in the 1.1−1.7 μm WFC3 bandpass, and the combined Kepler and WFC3 data are consistent with a flat-line model, indicating the presence of aerosols in the atmosphere. We compare the shape of Kepler-79d's transmission spectrum to predictions from a microphysical haze model that incorporates an outward particle flux due to ongoing mass loss. We find that photochemical hazes offer an attractive explanation for the observed properties of super-puffs like Kepler-79d, as they simultaneously render the near-infrared spectrum featureless and reduce the inferred envelope mass-loss rate by moving the measured radius (optical depth unity surface during transit) to lower pressures. We revisit the broader question of mass-loss rates for super-puffs and find that the age estimates and mass-loss rates for the majority of super-puffs can be reconciled if hazes move the photosphere from the typically assumed pressure of ∼10 mbar to m10 bar. Unified Astronomy Thesaurus concepts: Exoplanet atmospheres (487); Exoplanet evolution (491); Exoplanets (498) Supporting material: data behind figure, machine-readable tables

show abstract

The Compositional Diversity of Low-Mass Exoplanets

Cited by 49 publications

References 138 publications

GJ 1252 b: A 1.2 R_⊕ Planet Transiting an M3 Dwarf at 20.4 pc

GJ 1252 b: A 1.2 R_⊕ Planet Transiting an M3 Dwarf at 20.4 pc

Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

A Featureless Infrared Transmission Spectrum for the Super-puff Planet Kepler-79d

Contact Info

Product

Resources

About

The Compositional Diversity of Low-Mass Exoplanets

Cited by 49 publications

References 138 publications

GJ 1252 b: A 1.2 R⊕ Planet Transiting an M3 Dwarf at 20.4 pc

GJ 1252 b: A 1.2 R⊕ Planet Transiting an M3 Dwarf at 20.4 pc

Exploring Whether Super-puffs can be Explained as Ringed Exoplanets

A Featureless Infrared Transmission Spectrum for the Super-puff Planet Kepler-79d

Contact Info

Product

Resources

About

GJ 1252 b: A 1.2 R_⊕ Planet Transiting an M3 Dwarf at 20.4 pc

GJ 1252 b: A 1.2 R_⊕ Planet Transiting an M3 Dwarf at 20.4 pc