Proposal #673

Good morning, I'm Sauro Gaudenzi, my observer code is GSAD. In support of AAVSO alert no. 916, I kindly request the use of a telescope to observe the following objects: NSV 2091 - NSV 18716 - TW Cha - CVSO 107 - V0462 Ori - V0543 Ori - CVSO 35 - PTF1 4-2045 - FI Cha - WY Cha - UZ Cha - CW Cha. I request that five 40-second exposures be taken with a V filter and five 40-second exposures with a B filter once a week for each object, until the end of February. This proposal is subject to change by the TAC. Abstract:
Marbely Calderon (University of Michigan) writes: Young stellar objects (YSOs) are variable due to the rotation of the system, episodic accretion, and mass ejections (winds). We request simultaneous multi-color photometric observations in support of an upcoming spectroscopic campaign. The photometry will mainly be used to flux-calibrate these spectroscopic observations, for their analysis, and the characterization of the accretion state of the source. Justification:
Stars are born surrounded by disks of gas and dust, which slowly evolve into planetary systems. In this early stage, the stars are known as Young Stellar Objects (YSOs). Observations show that these disks disappear fairly quickly: by about 5 million years, roughly 80% of stars have already lost them. Our targets lie in this critical transition period, when only a small fraction of stars still retain their disks. By studying their light, we can measure how gas from the disk is actively falling onto the star (a process called accretion) and identify what that gas is made of. This gives us a direct glimpse of the material in the disk that may eventually form planets and smaller bodies. Additional Observer Input:
These observations will be used for absolute flux-calibration of the spectroscopy and to check if the system is currently outbursting. For this purpose, transformed photometry would be preferred but not required. Additionally, due to the immediacy of this campaign, sequences are currently in progress by the sequence team. Please take photometry immediately, but if there are no appropriate comparison stars, please check back in a couple days.