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Register a new userA 0.8-2.4 Micron Transmission Spectrum of the Hot Jupiter CoRoT-1b
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Hot Jupiters with brightness temperatures > ~2000K can have TiO and VO molecules as gaseous species in their atmospheres. The TiO and VO molecules can potentially induce temperature
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We report here the first infrared spectrum of the hot-Jupiter XO-1b. The observations were obtained with NICMOS instrument onboard the Hubble Space Telescope during a primary eclipse of the XO-1 system. Near photon-noise-limited spectroscopy between 1.2 and 1.8 micron allows us to determine the main composition of this hot-Jupiters planetary atmosphere with good precision. This is the third hot-Jupiters atmosphere for which spectroscopic data are available in the near IR. The spectrum shows the presence of water vapor (H2O), methane (CH4) and carbon dioxide (CO2), and suggests the possible presence of carbon monoxide (CO). We show that the published IRAC secondary transit emission photometric data are compatible with the atmospheric composition at the terminator determined from the NICMOS spectrum, with a range of possible mixing-ratios and thermal profiles; additional emission spectroscopy data are needed to reduce the degeneracy of the possible solutions. Finally, we note the similarity between the 1.2-1.8 micron transmission spectra of XO-1b and HD 209458b, suggesting that in addition to having similar stellar/orbital and planetary parameters the two systems may also have a similar exoplanetary atmospheric composition.
We present here new transmission spectra of the hot Jupiter HD-189733b using the SpeX instrument on the NASA Infrared Telescope Facility. We obtained two nights of observations where we recorded the primary transit of the planet in the J-, H- and K-bands simultaneously, covering a spectral range from 0.94 to 2.42 {mu}m. We used Fourier analysis and other de-trending techniques validated previously on other datasets to clean the data. We tested the statistical significance of our results by calculating the auto-correlation function, and we found that, after the detrending, auto-correlative noise is diminished at most frequencies. Additionally, we repeated our analysis on the out-of-transit data only, showing that the residual telluric contamination is well within the error bars. While these techniques are very efficient when multiple nights of observations are combined together, our results prove that even one good night of observations is enough to provide statistically meaningful data. Our observed spectra are consistent with space-based data recorded in the same wavelength interval by multiple instruments, indicating that ground-based facilities are becoming a viable and complementary option to spaceborne observatories. The best fit to the features in our data was obtained with water vapor. Our error bars are not small enough to address the presence of additional molecules, however by combining the information contained in other datasets with our results, it is possible to explain all the available observations with a modelled atmospheric spectrum containing water vapor, methane, carbon monoxide and hazes/clouds.
We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf host ($T_{eff}=3916^{+71}_{-63}~K$) in a P=2.674d orbit discovered as part of the Next Generation Transit Survey (NGTS). The planet has a mass of $0.812^{+0.066}_{-0.075}~M_{J}$, making it the most massive planet ever discovered transiting an M-dwarf. The radius of the planet is $1.33^{+0.61}_{-0.33}~R_{J}$. Since the transit is grazing, we determine this radius by modelling the data and placing a prior on the density from the population of known gas giant planets. NGTS-1b is the third transiting giant planet found around an M-dwarf, reinforcing the notion that close-in gas giants can form and migrate similar to the known population of hot Jupiters around solar type stars. The host star shows no signs of activity, and the kinematics hint at the star being from the thick disk population. With a deep (2.5%) transit around a $K=11.9$ host, NGTS-1b will be a strong candidate to probe giant planet composition around M-dwarfs via JWST transmission spectroscopy.
We present the optical transmission spectrum of the hot Jupiter WASP-104b based on one transit observed by the blue and red channels of the DBSP spectrograph at the Palomar 200-inch telescope and 14 transits observed by the MuSCAT2 four-channel imager at the 1.52 m Telescopio Carlos Sanchez. We also analyse 45 additional K2 transits, after correcting for the flux contamination from a companion star. Together with the transit light curves acquired by DBSP and MuSCAT2, we are able to revise the system parameters and orbital ephemeris, confirming that no transit timing variations exist. Our DBSP and MuSCAT2 combined transmission spectrum reveals an enhanced slope at wavelengths shorter than 630 nm and suggests the presence of a cloud deck at longer wavelengths. While the Bayesian spectral retrieval analyses favour a hazy atmosphere, stellar spot contamination cannot be completely ruled out. Further evidence, from transmission spectroscopy and detailed characterisation of the host stars activity, is required to distinguish the physical origin of the enhanced slope.
We present a new ground-based visible transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b, obtained as part of the ACCESS project. We derive the spectrum from five transits observed between 2016 and 2018, with combined wavelength coverage between 5200 {AA} - 9269 {AA} in 200 {AA} bins, and with a median precision of 247 ppm per bin. HAT-P-23bs relatively high surface gravity (g ~ 30 m/s^2), combined with updated stellar and planetary parameters from Gaia DR2, gives a 5-scale-height signal of 384 ppm for a hydrogen-dominated atmosphere. Bayesian models favor a clear atmosphere for the planet with the tentative presence of TiO, after simultaneously modeling stellar contamination, using spots parameter constraints from photometry. If confirmed, HAT-P-23b would be the first example of a high-gravity gas giant with a clear atmosphere observed in transmission at optical/NIR wavelengths; therefore, we recommend expanding observations to the UV and IR to confirm our results and further characterize this planet. This result demonstrates how combining transmission spectroscopy of exoplanet atmospheres with long-term photometric monitoring of the host stars can help disentangle the exoplanet and stellar activity signals.
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