Wavelength dependent transit depth of HATS-5b: a haze dominant atmosphere?

Abstract

The wavelength-dependent transit depth indicates the atmosphere composition of an exoplanet. We analyze the transit depth of HATS-5b using the data from the Transiting Exoplanet Survey Satellite (TESS) and compare the radius ratio of the planet to the star with the different band result in previous work. We generate a photometric pipeline to obtain the TESS light curve. The fitting of the HATS-5b light curve derives similar bandpass independent parameters compared to the reference work, e.g., the differences in the inclination and the semi-major axis within 1$\sigma$. We fix the bandpass-independent parameters to values from the previous work for comparison purposes. The wavelength-dependent $R_{p}/R_{\ast}$ obtained is 2.5% (1.9$\sigma$) smaller compared to the joint band result from the referenced work. The difference of $R_{p}$/$R_{\ast}$ suggests a haze-dominant model preferred by observation (with $\chi^{2}=1.68$) when fitting with different atmospheric models. The opaque featureless atmospheric model has a $\chi^{2}\sim4$, while the other models are ruled out with $\chi^{2}> 7$. We also predict an $R_{p}/R_{\ast}$ difference of ∼1$\%$, correlating the presence of water at $z$-band observation. This difference is detectable at 3$\sigma$ if the photometry precision reaches 500 ppm with 2 minute exposure for one-night observation.