# # Program information file # PROGRAM_ID 2024A020 PROGRAM_TITLE Decoding the inner disk of 'intense' Herbig Be stars using iSHELL PROGRAM_INV1 B Shridharan PROGRAM_INV2 Blesson Mathew PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG Intense Herbig Be [HBe] stars are early-type [B0-B5], young stars characterised by high near-infrared [NIR] excess and high Halpha equivalent width [EW], indicative of an active circumstellar environment with an inner disk and ongoing accretion through BL processes. This is distinct from the weak Herbig Be stars, where the inner disk has dissipated, as inferred from low NIR excess and weak Halpha excess. Our study plans to employ high-resolution spectroscopic techniques, leveraging instruments such as iSHELL to understand the inner [<10 au] circumstellar disks in these massive systems. We undertake a multifaceted investigation encompassing fundamental overtone and rovibrational CO emission lines, wavelength-dependent opacity of HI lines belonging to different series, and molecular lines [including OH, and H2O] that are observed in the K and M band regions. The higher resolution of iSHELL allows for detailed spectral analysis of CO and HI lines. This study focuses on intense HBe stars as a stepping stone towards comprehensively understanding these massive, young stars. By unraveling the complexities of their inner disk evolution and circumstellar environments, we aim to contribute significant insights into the broader processes governing star and planet formation. The evolution of gas and dust reservoirs in the immediate vicinity of Herbig stars plays a pivotal role in planet formation. Understanding the intricate properties and evolution of disks in stars undergoing BL accretion can provide vital insights into the broader context of stellar and planetary formation within the universe. PROGRAM_ABSTRACT_END