From protostars to exoplanets: insights from Gaia

In this talk, we will present two new results obtained using Gaia data release 2 (Gaia DR2).  Gaia provides extremely accurate photometry and astrometry, which can be used to determine precise stellar properties. Further, Gaia has a limiting magnitude of 21 in the G band, making it an excellent tool to search for extremely faint or embedded objects. Taking advantage of this, we have used Gaia DR2 data to identify optical counterparts to about 60 protostars in Orion. We will describe our analysis and discuss the possibility of exploring the photospheres of protostars in the visual/near-IR wavelengths. Gaia also provides accurate radial velocity and proper motions of stars, whic can be used to calculate the 3-D space velocities of stars. These 3-D velocities can then be used to calculate the velocity dispersion that can be used as a proxy for stellar age. Our analysis shows that massive planets, on average, are found around stars with a smaller velocity dispersion, indicating that Jupiter-like planets are generally hosted by relatively young (≤ 5 Gyr) stars. We also find that close-in, hotter (period ≤ 10 days) planets are preferentially found around younger stars compared to stars hosting warmer (period ≥ 10 days) planets. Our analysis and results highlight the importance of Gaia data in furthering our understanding of star and planet formation process.