Poster Open Access
To study exoplanet habitability, it is crucial to characterize planetary atmospheres. Observing transit-induced dimming of exoplanets in X-rays offers an unique tool (Perryman 2018). We have conducted a systematic study to search for possible transits of stars hosting exoplanets using Chandra data. In total, 53 stars are investigated and as a result, we found a significant transit signature from HD18733b which has been already reported by Poppenhaeger et al. (2013, ApJ, 773, 62), Although the other data show no significant transit feature. We found that even if we could observe transit durations in X-rays, it would be difficult to distinguish between variations caused by planets and those caused by flares. We report on our systematic study.