Observational Study Of Transmission Spectra Of Transitional Hot Jupiters

Hot Jupiter(HJ)is a special class of exoplanets.Two subgroups are classified,i.e.,classic HJ with a relatively low equilibrium temperature and ultrahot HJ(UP The hot Jupiter located in transition region can be referred to as transitional hot Jupiter.Research on these targets can reveal the appearance and internal mechanism of the transition of hot Jupiter’s atmospheric properties from a classical state to an extreme state.In order to clarify the atmospheric evolution rules of hot Jupiter at different temperatures and stages,and explore the connection and transition boundaries between classic hot Jupiter and ultra-hot Jupiter,this thesis selects HAT-P-32Ab,a representative of transitional hot Jupiter,to analyze its observational data and atmospheric retrieval,and improves the model based on low resolution spectral data to further accurately depict its atmospheric properties.The obtained methods and conclusions are validated and compared with 11 other representative hot Jupiters to explore the differences and connections between the characteristics and attributes of hot Jupiter.We shows the transit transmission spectrum in the optical band(399-939 nm)obtained through the transmission spectrum observation and data processing of HATP-32Ab using the Palomar Hale telescope,and performs atmospheric retrieval based on the previous transmission spectrum observation data of HAT-P-32Ab.In atmospheric retrieval,this paper integrates independent observation data from five devices:HST/STIS,Gemini-N/GMOS,LBT/MODS,GTC/OSIRIS,and P200/COSMIC,taking into account three theoretical assumptions:1.A one-dimensional homogeneous atmospheric model;A pseudo two-dimensional atmospheric model considering cloud and haze coverage;A pseudo two-dimensional atmospheric model considering the difference between morning and evening limb.By comparing three theoretical assumptions,our results show that the main characteristics of the transmission spectrum of HAT-P32Ab are a strong scattering slope at the blue end of the spectrum,a flat spectrum in the optical band,water absorption in the near infrared band,and carbon dioxide absorption in the infrared band;The high metallicity retrieved from the HAT-P-32b observation data can be well explained by the assumption of a pseudo two-dimensional model of the atmosphere,and the temperature difference retrieved from the pseudo two-dimensional model of the atmosphere coincides with the forward theoretical expectations of the general circulation model(GCM).11 hot Jupiters that have a wide coverage in the parameter space was selected for examination whether the aforementioned conclusions in this research are equally applicable to the differences and relationships between transitional hot Jupiter and hot Jupiter populations.The atmospheric retrieval shows that the pseudo two-dimensional model considering the difference between morning and evening can well fit the optical and infrared transmission spectrum observation data.The statistical analysis of atmospheric parameters obtained from the retrieval of hot Jupiter samples shows that there may be a trend of increasing metallicity in the hot Jupiter atmosphere as the planet mass decreases,and this trend is generally stronger than the trend of giant planets in the solar system.The temperature difference between the morning and evening atmospheres of Hot Jupiter showed a jump with the increase of equilibrium temperature at 2014-126 +150 K,and the temperature difference between the morning and evening in areas larger than the jump temperature significantly increased.This may be related to the evolution of atmospheric physics,chemistry,and dynamics during the transition from Hot Jupiter to Ultra-Hot Jupiter.The morning atmosphere of hot Jupiter may be strongly hazy,while the location of cloud top in the evening limb may be relatively deeper.