K2, Spitzer, and TESS Transits of Four Sub-Neptune Exoplanets
arXiv:2108.08889 · doi:10.3847/1538-3881/ac0e2f
Abstract
We present new Spitzer transit observations of four K2 transiting sub-Neptunes: K2-36c, K2-79b, K2-167b, and K2-212b. We derive updated orbital ephemerides and radii for these planets based on a joint analysis of the Spitzer, TESS, and K2 photometry. We use the EVEREST pipeline to provide improved K2 photometry, by detrending instrumental noise and K2's pointing jitter. We used a pixel level decorrelation method on the Spitzer observations to reduce instrumental systematic effects. We modeled the effect of possible blended eclipsing binaries, seeking to validate these planets via the achromaticity of the transits (K2 versus Spitzer). However, we find that Spitzer's signal-to-noise ratio for these small planets is insufficient to validate them via achromaticity. Nevertheless, by jointly fitting radii between K2 and Spitzer observations, we were able to independently confirm the K2 radius measurements. Due to the long time baseline between the K2 and Spitzer observations, we were also able to increase the precision of the orbital periods compared to K2 observations alone. The improvement is a factor of 3 for K2-36c, and more than an order of magnitude for the remaining planets. Considering possible JWST observations in 1/2023, previous 1 sigma uncertainties in transit times for these planets range from 74 to 434 minutes, but we have reduced them to the range of 8 to 23 minutes.
arXiv comment18 pages, 11 Figures, Accepted by The Astronomical Journal
References in corpus (42)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- emcee: The MCMC Hammer
- The Transiting Exoplanet Survey Satellite
- Analytic Lightcurves for Planetary Transit Searches
- A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
- The K2 Mission: Characterization and Early results
- The false positive rate of Kepler and the occurrence of planets
- Most 1.6 Earth-Radius Planets are not Rocky
- Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
- Probabilistic Forecasting of the Masses and Radii of Other Worlds
- A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
- A Framework for Prioritizing the TESS Planetary Candidates Most Amenable to Atmospheric Characterization
- Characterizing transiting exoplanet atmospheres with JWST
- Data analysis recipes: Using Markov Chain Monte Carlo
- Spitzer Secondary Eclipses of the Dense, Modestly-irradiated, Giant Exoplanet HAT-P-20b Using Pixel-Level Decorrelation
- EVEREST: Pixel Level Decorrelation of K2 Light curves
- Wotan: Comprehensive time-series de-trending in Python
- 197 Candidates and 104 Validated Planets in K2's First Five Fields
- K2SC: Flexible systematics correction and detrending of K2 light curves using Gaussian Process regression
- Orbital Phase Variations of the Eccentric Giant Planet HAT-P-2b
- 275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0-10
- Friends of Hot Jupiters II: No Correspondence Between Hot-Jupiter Spin-Orbit Misalignment and the Incidence of Directly Imaged Stellar Companions
- Friends of Hot Jupiters. IV. Stellar companions beyond 50 AU might facilitate giant planet formation, but most are unlikely to cause Kozai-Lidov migration
- Spitzer Observations Confirm and Rescue the Habitable-Zone Super-Earth K2-18b for Future Characterization
- Eleven Multi-planet Systems from K2 Campaigns 1 & 2 and the Masses of Two Hot Super-Earths
- Scaling K2. I. Revised Parameters for 222,088 K2 Stars and a K2 Planet Radius Valley at 1.9
- Statistical Characterization of Hot Jupiter Atmospheres using Spitzer's Secondary Eclipses
- A Lucky Imaging search for stellar sources near 74 transit hosts
- Low False-Positive Rate of Kepler Candidates Estimated From A Combination Of Spitzer And Follow-Up Observations
- 60 Validated Planets from K2 Campaigns 5-8
- Simulated JWST/NIRISS Transit Spectroscopy of Anticipated TESS Planets Compared to Select Discoveries from Space-Based and Ground-Based Surveys
- Updated Parameters and a New Transmission Spectrum of HD 97658b
- Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits
- On the Temperature Profiles and Emission Spectra of Mini-Neptune Atmospheres
- A Lucky Imaging search for stellar companions to transiting planet host stars
- Robo-AO Kepler Survey V: The effect of physically associated stellar companions on planetary systems
- Spitzer Observations of Exoplanets Discovered with The Kepler K2 Mission
- High-resolution Imaging of Transiting Extrasolar Planetary systems (HITEP). II. Lucky Imaging results from 2015 and 2016
- Spitzer transit follow-up of planet candidates from the K2 mission
- The K2 and TESS Synergy. I. Updated Ephemerides and Parameters for K2-114, K2-167, K2-237, and K2-261
- So close, so different: characterization of the K2-36 planetary system with HARPS-N