The future of astronomy in the coming decades will be shaped by the upcoming three extremely large optical telescopes, the Thirty Meter Telescope (TMT), the Giant Magellan Telescope (GMT) and the European Large Telescope (ELT). The USA astronomy and astrophysics 2020 decadal survey and the Canadian long-range plan for astronomy have recently recommended these large observatories as a top priority for ground-based astronomy for the upcoming decade. India is a 10% partner in one of these large observatories, the TMT, which is jointly funded by the Department of Science and Technology (DST) and Department of Atomic Energy (DAE). Here, we highlight India’s contributions to the development of the telescope and science instruments. The size of back-end science instruments scale with telescope aperture, hence, science instruments for TMT will be the biggest ever built for any telescope. Designing and building them requires broad collaboration within India, across TMT partnership and industries. India contributes >30% of the work share towards the development of wide field optical spectrometer (WFOS). India is part of the development of other first-light instruments, the infrared imaging spectrograph (IRIS) and multi-object diffraction-limited high-resolution infrared spectrograph (MODHIS). Infrared guide star catalog is an important contribution from India to these adaptive optics (AO)-assisted instruments. India leads the development of high-resolution optical spectrograph (HROS), a major workhorse among the first decade instruments of TMT. India is also part of the instrument development team of other first-decade instruments. Concerted efforts have been made to contribute to some of the TMT precursor instruments that will help us to maximize the scientific productivity when TMT is operational, especially in the area of exoplanet science and observations that require AO. India-TMT is part of the science team for the Keck high-resolution infrared spectrograph for exoplanet characterization (HISPEC), a precursor instrument to TMT-MODHIS. In addition, Indian Institute of Astrophysics (IIA) is participating in the science and development of Santa Cruz array of lenslets for exoplanet spectroscopy (SCALES) project for Keck, which is a direct imaging spectrograph for exoplanet studies and a precursor to the TMT planetary system imager.

With the third data release of the Gaia mission, GaiaDR3with its precise photometry and astrometry, it is now possible to study the behavior of stars at a scale never seen before. In this paper, we developed new criteria to identify T-Tauri stars (TTS) candidates using UV and optical color-magnitude diagrams (CMDs) bycombining the GALEX and Gaia surveys. We found 19 TTS candidates and five of them are newly identified TTS in the Taurus molecular cloud (TMC), not cataloged before as TMC members. For some of the TTS candidates, we also obtained optical spectra from several Indian telescopes. We also present the analysis of distance and proper motion of young stars in the Taurus using data from Gaia DR3. We found that the stars in Taurus show a bimodal distribution with distance, having peaks at 130.17$^{1.31}_{−1.24}$ pc and 156.25$^{1.86}_{−5.00}$ pc. The reason for this bimodality, we think, is due to the fact that different clouds in the TMC region are at different distances. We further showed that the two populations have similar ages and proper motion distribution. Using the Gaia DR3 CMD, we showed that the age of Taurus is consistent with 1 Myr.