Spitzer Transit and Secondary Eclipse Photometry of GJ 436b

By D. Deming, J. Harrington, Gregory Laughlin, Sara Seager, S. Navarro, W. C. Bowman, K. Horning. 2007

162 citations recorded by the source corpus.

We report the results of infrared (8 μm) transit and secondary eclipse photometry of the hot Neptune exoplanet, GJ 436b using Spitzer. The nearly photon-limited precision of these data allows us to measure an improved radius for the planet and to detect the secondary eclipse. The transit (centered at HJD = 2454280.78149 ± 0.00016) shows the flat-bottomed shape typical of infrared transits, and it precisely defines the planet-to-star radius ratio (0.0839 ± 0.0005), independent of the stellar properties. However, we obtain the planetary radius, as well as the stellar mass and radius, by fitting to the transit curve simultaneously with an empirical mass-radius relation for M dwarfs (M = R). We find R* = M* = 0.47 ± 0.02 in solar units, and Rp = 27,600 ± 1170 km (4.33 ± 0.18 R⊕). This radius significantly exceeds the radius of a naked ocean planet and requires a gaseous hydrogen-helium envelope. The secondary eclipse occurs at phase 0.587 ± 0.005, proving a significant orbital eccentricity (e = 0.150 ± 0.012). The amplitude of the eclipse [(5.7 ± 0.8) × 10-4] indicates a brightness temperature for the planet of T = 712 ± 36 K. If this is indicative of the planet's physical temperature, it suggests the occurrence of tidal heating in the planet. An uncharacterized second planet likely provides ongoing gravitational perturbations that maintain GJ 436b's orbit eccentricity over long timescales.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/94371278372f6c31b9506612744aa002766c778b

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Jon Fortney
2. N. Madhusudhan
3. D. Charbonneau
4. Sara Seager
5. A. Showman
6. J. Southworth
7. H. Knutson
8. D. Deming

In Instrumentation

1. Jon Fortney
2. J. Southworth
3. D. Charbonneau
4. N. Madhusudhan
5. A. Showman
6. Sara Seager
7. H. Knutson
8. J. Winn

In Statistical and Nonlinear Physics

1. Jon Fortney
2. A. Showman
3. Sara Seager
4. H. Knutson
5. Leslie A. Rogers
6. D. Charbonneau
7. M. Marley
8. J. D'esert

Citations in the corpus

• Exoplanet Atmospheres: Physical Processes (2010, background): “Shown are observations of the transit (left panels) and eclipse (right panels) of the hot Neptune planet GJ436b (Deming et al. 2007).”
• TIDALLY HEATED TERRESTRIAL EXOPLANETS: VISCOELASTIC RESPONSE MODELS (2009, background): “…exoplanets is important partly because eccentricities in the overall exoplanet population are higher than expected (Butler et al. 2006; Tremaine & Zakamska 2004; Namouni 2005), e.g. GJ436b at e=0.15 (Deming et al. 2007), suggesting the importance and prevalence of multiple planet interactions.”
• Tidal Evolution of Close-in Extrasolar Planets (2007, background): “Planetary data were taken from a variety of sources: Bakos et al. 2007a; Bakos et al. 2007b; Butler et al. 2006; Da Silva et al. 2006; Deming et al. 2007; Gillon et al. 2007; Johnson et al. 2006; Knutson et al. 2007; Laughlin et al. 2005; Lovis et al. 2006; McArthur et al. 2004; Maness 2007; Mayor…”
• A FRAMEWORK FOR QUANTIFYING THE DEGENERACIES OF EXOPLANET INTERIOR COMPOSITIONS (2009, methodology): “…by Gillon et al. (2007b), substantial efforts have been made to measure its mass and radius using photometric data from the Spitzer Space Telescope (Deming et al. 2007; Gillon et al. 2007a), from the Hubble Space Telescope (Bean et al. 2008), and from further ground-based observations (e.g.…”
• The 3.6-8.0 μm Broadband Emission Spectrum of HD 209458b: Evidence for an Atmospheric Temperature Inversion (2007, background): “Lastly, the core-dominated hot Jupiter HD 149026b (Harrington et al. 2007) and the hot Neptune GJ 436b (Deming et al. 2007b; Demory et al. 2007) have both been observed at 8.0 µm.”
• THE ATMOSPHERIC SIGNATURES OF SUPER-EARTHS: HOW TO DISTINGUISH BETWEEN HYDROGEN-RICH AND HYDROGEN-POOR ATMOSPHERES (2008, background): “…have resulted in measurements of brightness temperatures (Deming et al. 2005; Charbonneau et al. 2005; Deming et al. 2006; Harrington et al. 2007; Deming et al. 2007; Demory et al. 2007; Knutson et al. 2008) as well as emission spectra (Grillmair et al. 2007; Richardson et al. 2007; Swain et al.…”
• Observational Evidence for Tidal Interaction in Close Binary Systems (2007, background): “…through the secondary eclipse of HD 209458b (Deming et al. 2005; 2007), TrES-1 (Charbonneau et al. 2005), 189733b (Deming et al. 2006), and Gliese 436b (Deming et al. 2007; Demory et al. 2007), and even by the phase modulation of the non-transiting planet around υ And (Harrington et al. 2006).”
• Theoretical Spectral Models of the Planet HD 209458b with a Thermal Inversion and Water Emission Bands (2007, methodology): “…the direct detection of planetary atmospheres via lowresolution spectroscopy and precision IR photometry is now a reality (Charbonneau et al. 2005; Deming et al. 2005,2006,2007; Grillmair et al. 2007; Richardson et al. 2007; Harrington et al. 2006,2007; Knutson et al. 2007b,c; Cowan et al. 2007).”
• Homogeneous studies of transiting extrasolar planets – I. Light-curve analyses (2008, methodology): “The residuals of the fit are plotted at the bottom of the figure, offset from zero. the transit has been obtained using the Spitzer Space Telescope (Gillon et al. 2007a; Deming et al. 2007a).”
• Analytic Approximations for Transit Light-Curve Observables, Uncertainties, and Covariances (2008, background): “…of uniform brightness (no limb darkening) is valid for mid-infrared bandpasses, which are increasingly being used for transit observations (see, e.g., Harrington et al. 2007, Knutson et al. 2007, Deming et al. 2007), and is a good approximation even for near-infrared and far-red bandpasses.”
• MULTIWAVELENGTH CONSTRAINTS ON THE DAY–NIGHT CIRCULATION PATTERNS OF HD 189733b (2008, background): “Moreover, GJ 436b is likely only pseudo-synchronized, as it has an orbital eccentricity of 0.15 (Deming et al. 2007; Demory et al. 2007), which further complicates this picture.”
• SEARCH FOR CARBON MONOXIDE IN THE ATMOSPHERE OF THE TRANSITING EXOPLANET HD 189733b (2009, result): “This common observational strategy matches that of recent Spitzer observations of HD 189733 and GJ 436 (Knutson et al. 2007; Deming et al. 2007, Gillon et al. 2007; Agol et al. 2008) 2.2.”
• A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres (2007, background): “These included secondary eclipses for HD 189733b (Deming et al. 2006), HD 149026b (Harrington et al. 2007), GJ 436b (Deming et al. 2007; Demory et al. 2007), and a wealth of new (yet to be published) data for∼10 other systems.”
• HAT-P-11b: A SUPER-NEPTUNE PLANET TRANSITING A BRIGHT K STAR IN THE KEPLER FIELD (2009, background): “The RV amplitude of GJ 436 (K = 18.34±0.52m s−1, T08) is larger and better determined than HAT-P-11b (K = 11.6± 1.2m s−1), and the transits are deeper (6.5mmag vs. 4.2mmag), and have even been observed from space by Spitzer (Gillon et al. 2007; Deming et al. 2007) and HST (Bean et al. 2008).”
• The HARPS search for southern extra-solar planets - XXXI. The M-dwarf sample (2011, background): “Finding that GJ 436 b undergoes transits has enabled a wealth of detailed studies such as the determinations of the planet’s true mass and radius and measurements of its effective temperature and orbital eccentricity (Gillon et al. 2007a; Demory et al. 2007; Deming et al. 2007).”
• LYα TRANSIT SPECTROSCOPY AND THE NEUTRAL HYDROGEN TAIL OF THE HOT NEPTUNE GJ 436b (2014, background): “While many studies utilize IR (700 nm − 3 µm) (e.g. Deming et al. 2007) and optical (400 − 700 nm) (e.g. Butler et al. 2004) wavelengths, UV (1000− 4000 Å) observations provide a unique opportunity to characterize exoplanet exospheres.”
• Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres (2007, methodology): “While large, this value is comparable to expected radius uncertanties for these planets (Gillon et al. 2007b,a; Deming et al. 2007).”