Examinando por Autor "Sing, D. K."

Mostrando 1 - 8 de 8

Acceso Abierto
Evidence of a Clear Atmosphere for WASP-62b: The Only Known Transiting Gas Giant in the JWST Continuous Viewing Zone
(IOP Science Publishing, 2021-01-11) Alam, M. K.; López Morales, M.; MacDonald, R. J.; Nikolov, N.; Kirk, J.; Goyal, J. M.; Sing, D. K.; Wakeford, H. R.; Rathcke, A. D.; Deming, D. L.; Sanz Forcada, J.; Lewis, N. K.; Barstow, J. K.; Mikal Evans, T.; Buchhave, L. A.; National Aeronautics and Space Administration (NASA); National Science Foundation (NSF); Agencia Estatal de Investigación (AEI); Alam, M. K. [0000-0003-4157-832X]; López Morales, M. [0000-0003-3204-8183]; MacDonald, R. J. [0000-0003-4816-3469]; Nikolov, N. [0000-0002-6500-3574]; Kirk, J. [0000-0002-4207-6615]; Goyal, J. M. [0000-0002-8515-7204]; Sing, D. K. [0000-0001-6050-7645]; Wakeford, H. R. [0000-0003-4328-3867]; Rathcke, A. D. [0000-0002-4227-4953]; Deming, D. L. [0000-0001-5727-4094]; Sanz Forcada, J. [0000-0002-1600-7835]; Lewis, N. K. [0000-0002-8507-1304]; Barstow, J. K. [0000-0003-3726-5419]; Mikal Evans, T. [0000-0001-5442-1300]; Buchhave, L. A. [0000-0003-1605-5666]
Exoplanets with cloud-free, haze-free atmospheres at the pressures probed by transmission spectroscopy represent a valuable opportunity for detailed atmospheric characterization and precise chemical abundance constraints. We present the first optical to infrared (0.3−5 μm) transmission spectrum of the hot Jupiter WASP-62b, measured with Hubble/STIS and Spitzer/IRAC. The spectrum is characterized by a 5.1σ detection of Na i absorption at 0.59 μm, in which the pressure-broadened wings of the Na D-lines are observed from space for the first time. A spectral feature at 0.4 μm is tentatively attributed to SiH at 2.1σ confidence. Our retrieval analyses are consistent with a cloud-free atmosphere without significant contamination from stellar heterogeneities. We simulate James Webb Space Telescope (JWST) observations, for a combination of instrument modes, to assess the atmospheric characterization potential of WASP-62b. We demonstrate that JWST can conclusively detect Na, H2O, FeH, NH3, CO, CO2, CH4, and SiH within the scope of its Early Release Science (ERS) program. As the only transiting giant planet currently known in the JWST Continuous Viewing Zone, WASP-62b could prove a benchmark giant exoplanet for detailed atmospheric characterization in the James Webb era.
Acceso Abierto
HST PanCET Program: A Complete Near-UV to Infrared Transmission Spectrum for the Hot Jupiter WASP-79b
(IOP Science Publishing, 2021-09-10) Rathcke, A. D.; MacDonald, R. J.; Barstow, J. K.; Goyal, J. M.; López Morales, M.; Mendoça, J. M.; Sanz Forcada, J.; Henry, G. W.; Sing, D. K.; Alam, M. K.; Agencia Estatal de Investigación (AEI); Rathcke, A. D. [0000-0002-4227-4953]; MacDonald, R. J. [0000-0003-4816-3469]; Barstow, J. K. [0000-0003-3726-5419]; Goyal, J. M. [0000-0002-8515-7204]; López Morales, M. [0000-0003-3204-8183]; Mendoça, J. M. [0000-0002-6907-4476]; Sanz Forcada, J. [0000-0002-1600-7835]; Henry, G. W. [0000-0003-4155-8513]; Sing, D. K. [0000-0001-6050-7645]; Alam, M. K. [0000-0003-4157-832X]; Lewis, N. K. [0000-0002-8507-1304]; Chubb, K. L. [0000-0002-4552-4559]; Taylor, J. [0000-0003-4844-9838]; Nikolov, N. [0000-0002-6500-3574]; Buchhave, L. A. [0000-0003-1605-5666]
We present a new optical transmission spectrum of the hot Jupiter WASP-79b. We observed three transits with the STIS instrument mounted on the Hubble Space Telescope (HST), spanning 0.3–1.0 μm. Combining these transits with previous observations, we construct a complete 0.3–5.0 μm transmission spectrum of WASP-79b. Both HST and ground-based observations show decreasing transit depths toward blue wavelengths, contrary to expectations from Rayleigh scattering or hazes. We infer atmospheric and stellar properties from the full near-UV to infrared transmission spectrum of WASP-79b using three independent retrieval codes, all of which yield consistent results. Our retrievals confirm previous detections of H2O (at 4.0σ confidence) while providing moderate evidence of H− bound–free opacity (3.3σ) and strong evidence of stellar contamination from unocculted faculae (4.7σ). The retrieved H2O abundance (∼1%) suggests a superstellar atmospheric metallicity, though stellar or substellar abundances remain consistent with present observations (O/H = 0.3–34× stellar). All three retrieval codes obtain a precise H− abundance constraint: log(${X}_{{{\rm{H}}}^{-}}$) ≈ −8.0 ± 0.7. The potential presence of H− suggests that James Webb Space Telescope observations may be sensitive to ionic chemistry in the atmosphere of WASP-79b. The inferred faculae are ∼500 K hotter than the stellar photosphere, covering ∼15% of the stellar surface. Our analysis underscores the importance of observing UV–optical transmission spectra in order to disentangle the influence of unocculted stellar heterogeneities from planetary transmission spectra.
Acceso Abierto
HST PanCET program: non-detection of atmospheric escape in the warm Saturn-sized planet WASP-29 b
(EDP Sciences, 2021-05-07) Dos Santos, L. A.; Bourrier, V.; Ehrenreich, D.; Sanz Forcada, J.; López Morales, M.; Sing, D. K.; García Muñoz, Antonio; Henry, G. W.; Lavvas, P.; Lecavelier des Etangs, A.; Mikal Evans, T.; Vidal Madjar, A.; Wakeford, H. R.; Centre National D'Etudes Spatiales (CNES); European Research Council (ERC); Agencia Estatal de Investigación (AEI); Dos Santos, L. A. [0000-0002-2248-3838]; Sanz Forcada, J. [0000-0002-1600-7835]; López Morales, M. [0000-0003-3204-8183]; Sing, D. K. [0000-0001-6050-7645]; García Muñoz, A. [0000-0003-1756-4825]; Henry, G. W. [0000-0003-4155-8513]; Lecavelier des Etangs, A. [0000-0002-5637-5253]; Mikal Evans, T. [0000-0001-5442-1300]
Short-period gas giant exoplanets are susceptible to intense atmospheric escape due to their large scale heights and strong high-energy irradiation. This process is thought to occur ubiquitously, but to date we have only detected direct evidence of atmospheric escape in hot Jupiters and warm Neptunes. The latter planets are particularly more sensitive to escape-driven evolution as a result of their lower gravities with respect to Jupiter-sized planets. But the paucity of cases for intermediate, Saturn-sized exoplanets at varying levels of irradiation precludes a detailed understanding of the underlying physics in atmospheric escape of hot gas giants. Aiming to address this issue, our objectives here are to assess the high-energy environment of the warm (Teq = 970 K) Saturn WASP-29 b and search for signatures of atmospheric escape. We used far-ultraviolet observations from the Hubble Space Telescope to analyze the flux time series of H I, C II, Si III, Si IV, and N V during the transit of WASP-29 b. At 88 pc, a large portion of the Lyman-α core of the K4V-type host WASP-29 is attenuated by interstellar medium absorption, limiting our ability to probe the escape of H at velocities between −84 and +35 km s−1. At 3σ confidence, we rule out any in-transit absorption of H I larger than 92% in the Lyman-α blue wing and 19% in the red wing. We found an in-transit flux decrease of 39%−11%+12% in the ground-state C II emission line at 1334.5 Å. But due to this signal being significantly present in only one visit, it is difficult to attribute a planetary or stellar origin to the ground-state C II signal. We place 3σ absorption upper limits of 40, 49, and 24% on Si III, Si IV, and for excited-state C II at 1335.7 Å, respectively. Low activity levels and the faint X-ray luminosity suggest that WASP-29 is an old, inactive star. Nonetheless, an energy-limited approximation combined with the reconstructed EUV spectrum of the host suggests that the planet is losing its atmosphere at a relatively large rate of 4 × 109 g s−1. The non-detection at Lyman-α could be partly explained by a low fraction of escaping neutral hydrogen, or by the state of fast radiative blow-out we infer from the reconstructed Lyman-α line.
Acceso Abierto
The Hubble PanCET Program: A Metal-rich Atmosphere for the Inflated Hot Jupiter HAT-P-41b
(IOP Science Publishing, 2021-01-06) Sheppard, K. B.; Welbanks, L.; Mandell, A. M.; Madhusudhan, N.; Nikolov, N.; Deming, D. L.; Henry, G. W.; Williamson, M. H.; Sing, D. K.; López Morales, M.; Ih, J.; Sanz Forcada, J.; Lavvas, P.; Ballester, G. E.; Evans, T. M.; García Muñoz, Antonio; Dos Santos, L. A.; National Aeronautics and Space Administration (NASA); Sheppard, K. B. [0000-0003-4552-9541]; Welbanks, L. [0000-0003-0156-4564]; Mandell, A. M. [0000-0002-8119-3355]; Madhusudhan, M. [0000-0002-4869-000X]; Nikolov, N. [0000-0002-6500-3574]; Deming, D. [0000-0001-5727-4094]; Sing, D. K. [0000-0001-6050-7645]; Henry, G. W. [0000-0003-4155-8513]; López Morales, M. [0000-0003-3204-8183]; Ih, J. [0000-0003-2775-653X]; Sanz Forcada, J. [0000-0002-1600-7835]; Lavvas, P. [0000-0002-5360-3660]; Evans, T. M. [0000-0001-5442-1300]; García Muñoz, A. [0000-0003-1756-4825]; Dos Santos, L. A. [0000-0002-2248-3838]
We present a comprehensive analysis of the 0.3–5 μm transit spectrum for the inflated hot Jupiter HAT-P-41b. The planet was observed in transit with Hubble STIS and WFC3 as part of the Hubble Panchromatic Comparative Exoplanet Treasury (PanCET) program, and we combine those data with warm Spitzer transit observations. We extract transit depths from each of the data sets, presenting the STIS transit spectrum (0.29–0.93 μm) for the first time. We retrieve the transit spectrum both with a free-chemistry retrieval suite (AURA) and a complementary chemical equilibrium retrieval suite (PLATON) to constrain the atmospheric properties at the day–night terminator. Both methods provide an excellent fit to the observed spectrum. Both AURA and PLATON retrieve a metal-rich atmosphere for almost all model assumptions (most likely O/H ratio of ${\mathrm{log}}_{10}Z/{Z}_{\odot }={1.46}_{-0.68}^{+0.53}$ and ${\mathrm{log}}_{10}Z/{Z}_{\odot }={2.33}_{-0.25}^{+0.23}$, respectively); this is driven by a 4.9σ detection of H2O as well as evidence of gas absorption in the optical (>2.7σ detection) due to Na, AlO, and/or VO/TiO, though no individual species is strongly detected. Both retrievals determine the transit spectrum to be consistent with a clear atmosphere, with no evidence of haze or high-altitude clouds. Interior modeling constraints on the maximum atmospheric metallicity (${\mathrm{log}}_{10}Z/{Z}_{\odot }\lt 1.7$) favor the AURA results. The inferred elemental oxygen abundance suggests that HAT-P-41b has one of the most metal-rich atmospheres of any hot Jupiters known to date. Overall, the inferred high metallicity and high inflation make HAT-P-41b an interesting test case for planet formation theories.
Acceso Abierto
The Hubble PanCET program: long-term chromospheric evolution and flaring activity of the M dwarf host GJ 3470
(EDP Sciences, 2021-06-08) Bourrier, V.; Dos Santos, L. A.; Sanz Forcada, J.; García Muñoz, Antonio; Henry, G. W.; Lavvas, P.; Lecavelier, A.; López Morales, M.; Mikal Evans, T.; Sing, D. K.; Wakeford, H. R.; Ehrenreich, D.; European Research Council (ERC)
Neptune-size exoplanets seem particularly sensitive to atmospheric evaporation, making it essential to characterize the stellar high-energy radiation that drives this mechanism. This is particularly important with M dwarfs, which emit a large and variable fraction of their luminosity in the ultraviolet and can display strong flaring behavior. The warm Neptune GJ 3470b, hosted by an M2 dwarf, was found to harbor a giant exosphere of neutral hydrogen thanks to three transits observed with the Hubble Space Telescope Imaging Spectrograph (HST/STIS). Here we report on three additional transit observations from the Panchromatic Comparative Exoplanet Treasury program, obtained with the HST Cosmic Origin Spectrograph. These data confirm the absorption signature from GJ 3470b’s exosphere in the stellar Lyman-α line and demonstrate its stability over time. No planetary signatures are detected in other stellar lines, setting a 3σ limit on GJ 3470b’s far-ultraviolet (FUV) radius at 1.3 times its Roche lobe radius. We detect three flares from GJ 3470. They show different spectral energy distributions but peak consistently in the Si III line, which traces intermediate-temperature layers in the transition region. These layers appear to play a particular role in GJ 3470’s activity as emission lines that form at lower or higher temperatures than Si III evolved differently over the long term. Based on the measured emission lines, we derive synthetic X-ray and extreme-ultraviolet (X+EUV, or XUV) spectra for the six observed quiescent phases, covering one year, as well as for the three flaring episodes. Our results suggest that most of GJ 3470’s quiescent high-energy emission comes from the EUV domain, with flares amplifying the FUV emission more strongly. The neutral hydrogen photoionization lifetimes and mass loss derived for GJ 3470b show little variation over the epochs, in agreement with the stability of the exosphere. Simulations informed by our XUV spectra are required to understand the atmospheric structure and evolution of GJ 3470b and the role played by evaporation in the formation of the hot-Neptune desert.
Acceso Abierto
The Hubble Space Telescope PanCET Program: An Optical to Infrared Transmission Spectrum of HAT-P-32Ab
(The Institute of Physics (IOP), 2020-07-02) Alam, M. K.; López Morales, M.; Nikolov, N.; Sing, D. K.; Henry, G. W.; Baxter, C.; Désert, J. M.; Barstow, J. K.; Mikal Evans, T.; Bourrier, V.; Lavvas, P.; Wakeford, H. R.; Williamson, M. H.; Sanz Forcada, J.; Buchhave, L. A.; Cohen, O.; García Muñoz, Antonio; Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); European Research Council (ERC); Alam, M. K. [0000-0003-4157-832X]; López Morales, M. [0000-0003-3204-8183]; Nikolov, N. [0000-0002-6500-3574]; Sing, D. K. [0000-0001-6050-7645]; Henry, G. W. [0000-0003-4155-8513]; Baxter, C. [0000-0003-3438-843X]; Désert, J. M. [0000-0002-0875-8401]; Barstow, J. K. [0000-0003-3726-5419]; Mikal Evans, T. [0000-0001-5442-1300]; Bourrier, V. [0000-0002-9148-034X]; Lavvas, P. [0000-0002-5360-3660]; Wakeford, H. R. [0000-0003-4328-3867]; Forcada, J. S. [0000-0002-1600-7835]; Buchhave, L. A. [0000-0003-1605-5666]; Cohen, O. [0000-0003-3721-0215]; García Muñoz, A. [0000-0003-1756-4825]
We present a 0.3−5 μm transmission spectrum of the hot Jupiter HAT-P-32Ab observed with the Space Telescope Imaging Spectrograph and Wide Field Camera 3 instruments mounted on the Hubble Space Telescope, combined with Spitzer Infrared Array Camera photometry. The spectrum is composed of 51 spectrophotometric bins with widths ranging between 150 and 400 Å, measured to a median precision of 215 ppm. Comparisons of the observed transmission spectrum to a grid of 1D radiative-convective equilibrium models indicate the presence of clouds/hazes, consistent with previous transit observations and secondary eclipse measurements. To provide more robust constraints on the planet's atmospheric properties, we perform the first full optical to infrared retrieval analysis for this planet. The retrieved spectrum is consistent with a limb temperature of ${1248}_{-92}^{+92}$ K, a thick cloud deck, enhanced Rayleigh scattering, and ~10× solar H2O abundance. We find log(Z/Z⊙) = ${2.41}_{-0.07}^{+0.06}$, and compare this measurement with the mass–metallicity relation derived for the solar system.
Acceso Abierto
Transmission Spectroscopy of WASP-79b from 0.6 to 5.0 μm
(The Institute of Physics (IOP), 2020-01-10) Sotzen, K. S.; Stevenson, K. B.; Sing, D. K.; Kilpatrick, B. M.; Wakeford, H. R.; Filippazzo, J. C.; Lewis, N. K.; Hörst, S. M.; López Morales, M.; Henry, G. W.; Buchhave, L. A.; Ehrenreich, D.; Fraine, J. D.; García Muñoz, Antonio; Jayaraman, R.; Lavvas, P.; Des Etangs, A. L.; Marley, M. S.; Nikolov, N.; Rathcke, A. D.; Sánz Forcada, J.; European Research Council (ERC); National Aeronautics and Space Administration (NASA); Agencia Estatal de Investigación (AEI); Swiss National Science Foundation (SNSF); 0000-0001-7393-2368; 0000-0002-7352-7941; 0000-0001-6050-7645; 0000-0003-4220-600X; 0000-0003-4328-3867; 0000-0002-0201-8306; 0000-0002-8507-1304; 0000-0003-4596-0702; 0000-0003-4155-8513; 0000-0003-1605-5666; 0000-0001-9704-5405; 0000-0003-1756-4825; 0000-0002-5360-3660; 0000-0002-5251-2943; 0000-0002-6500-3574; 0000-0002-1600-7835
As part of the Panchromatic Exoplanet Treasury program, we have conducted a spectroscopic study of WASP-79b, an inflated hot Jupiter orbiting an F-type star in Eridanus with a period of 3.66 days. Building on the original WASP and TRAPPIST photometry of Smalley et al., we examine Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) (1.125–1.650 μm), Magellan/Low Dispersion Survey Spectrograph (LDSS)-3C (0.6–1 μm) data, and Spitzer data (3.6 and 4.5 μm). Using data from all three instruments, we constrain the water abundance to be −2.20 ≤ log(H2O) ≤ −1.55. We present these results along with the results of an atmospheric retrieval analysis, which favor inclusion of FeH and H− in the atmospheric model. We also provide an updated ephemeris based on the Smalley, HST/WFC3, LDSS-3C, Spitzer, and Transiting Exoplanet Survey Satellite (TESS) transit times. With the detectable water feature and its occupation of the clear/cloudy transition region of the temperature/gravity phase space, WASP-79b is a target of interest for the approved James Webb Space Telescope (JWST) Director's Discretionary Early Release Science (ERS) program, with ERS observations planned to be the first to execute in Cycle 1. Transiting exoplanets have been approved for 78.1 hr of data collection, and with the delay in the JWST launch, WASP-79b is now a target for the Panchromatic Transmission program. This program will observe WASP-79b for 42 hr in four different instrument modes, providing substantially more data by which to investigate this hot Jupiter.
Acceso Abierto
WASP-52b. The effect of star-spot correction on atmospheric retrievals
(Oxford Academics: Oxford University Press, 2019-11-18) Bruno, G.; Lewis, N. K.; Alam, M. K.; López Morales, M.; Barstow, J. K.; Wakeford, H. R.; Sing, D. K.; Henry, G. W.; Ballester, G. E.; Bourrier, V.; Buchhave, L. A.; Cohen, O.; Mikal Evans, T.; García Muñoz, Antonio; Lavvas, P.; Sanz Forcada, J.; Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); European Research Council (ERC); Deutsche Forschungsgemeinschaft (DFG); Buchhave, L. A. [0000-0003-1605-5666]; Bruno, G. [0000-0002-3288-0802]; Sing, D. [0000-0001-6050-7645]; Mikal Evans, T. [0000-0001-5442-1300]; Alam, M. [0000-0003-4157-832X]; Wakeford, H. [0000-0003-4328-3867]
We perform atmospheric retrievals on the full optical to infrared (⁠0.3−5μm⁠) transmission spectrum of the inflated hot Jupiter WASP-52b by combining HST/STIS, WFC3 IR, and Spitzer/IRAC observations. As WASP-52 is an active star that shows both out-of-transit photometric variability and star-spot crossings during transits, we account for the contribution of non-occulted active regions in the retrieval. We recover a 0.1–10× solar atmospheric composition, in agreement with core accretion predictions for giant planets, and no significant contribution of aerosols. We also obtain a <3000 K temperature for the star-spots, a measure which is likely affected by the models used to fit instrumental effects in the transits, and a 5 per cent star-spot fractional coverage, compatible with expectations for the host star’s spectral type. Such constraints on the planetary atmosphere and on the activity of its host star will inform future JWST GTO observations of this target.