# Towards a comprehensive view of accretion, inner disks, and extinction in classical T Tauri stars: an ODYSSEUS study of the Orion OB1b association

**Authors:** Caeley V. Pittman, Catherine C. Espaillat, Connor E. Robinson, Thanawuth Thanathibodee, Nuria Calvet, John Wendeborn, Jesus Hernández, Carlo F. Manara, Fred Walter, Péter Ábrahám, Juan M. Alcalá, Sílvia H. P. Alencar, Nicole Arulanantham, Sylvie Cabrit, Jochen Eislöffel, Eleonora Fiorellino, Kevin France, Manuele Gangi, Konstantin Grankin, Gregory J. Herczeg  
**arXiv:** [2208.04986](https://arxiv.org/abs/2208.04986)  
**Date:** 2022-08-09  
**Summary page:** https://www.summarizepaper.com/en/paper/2208.04986v1/

## Key points

- Planet formation around T Tauri stars is influenced by the coevolution of these stars and their surrounding protoplanetary disks.
- Researchers used magnetospheric accretion and inner disk wall model fits to NUV-NIR spectra of nine classical T Tauri stars in Orion OB1b as part of the Outflows and Disks around Young Stars: Synergies for the Exploration of ULLYSES Spectra (ODYSSEUS) Survey.
- Accretion rates for these targets are relatively high for their intermediate age of 5.0 Myr, with rates ranging from $0.5-17.2 \times 10^{-8}$ M$_{\odot}$/yr and a median value of $1.2\times 10^{-8}$ M$_{\odot}$/yr.
- NIR excesses were found to be fit with 1200-1800 K inner disk walls located at 0.05-0.10 AU from the host stars.
- The choice in extinction law can significantly impact measured accretion rates, highlighting its significance in future studies.
- This analysis will be extended to a complete sample of T Tauri stars being observed through ULLYSES in order to better understand accretion and inner disks in star-forming regions with different ages and stellar populations.
- The study was conducted as part of an effort to explore young star outflows and disks using data from multiple observatories including Hubble Space Telescope, Very Large Telescope, Spitzer Space Telescope, Chandra X-ray Observatory, among others.
- The ULLYSES program aims to provide a comprehensive spectral library of young stars in order to better understand their formation and evolution.
- The team's findings contribute to our understanding of planet formation around T Tauri stars and the role of accretion rates and inner disk walls in this process by providing insight into how they influence each other over time during star formation processes in different environments across various stellar populations.

## Summary

The formation of planets around T Tauri stars is influenced by the coevolution of these stars and their surrounding protoplanetary disks. In a recent study, researchers used magnetospheric accretion and inner disk wall model fits to NUV-NIR spectra of nine classical T Tauri stars in Orion OB1b as part of the Outflows and Disks around Young Stars: Synergies for the Exploration of ULLYSES Spectra (ODYSSEUS) Survey. The team utilized NUV-optical spectra from the Hubble UV Legacy Library of Young Stars as Essential Standards (ULLYSES) Director's Discretionary Program and optical-NIR spectra from the PENELLOPE VLT Large Programme to determine that the accretion rates for these targets are relatively high for their intermediate age of 5.0 Myr, with rates ranging from $0.5-17.2 \times 10^{-8}$ M$_{\odot}$/yr and a median value of $1.2\times 10^{-8}$ M$_{\odot}$/yr. Additionally, NIR excesses were found to be fit with 1200-1800 K inner disk walls located at 0.05-0.10 AU from the host stars. It is important to note that the choice in extinction law can significantly impact measured accretion rates, highlighting its significance in future studies. This analysis will be extended to a complete sample of T Tauri stars being observed through ULLYSES in order to better understand accretion and inner disks in star-forming regions with different ages and stellar populations. Further context reveals that this study was conducted as part of an effort to explore young star outflows and disks using data from multiple observatories including Hubble Space Telescope, Very Large Telescope, Spitzer Space Telescope, Chandra X-ray Observatory, among others. The ULLYSES program aims to provide a comprehensive spectral library of young stars in order to better understand their formation and evolution. The team's findings contribute to our understanding of planet formation around T Tauri stars and the role of accretion rates and inner disk walls in this process by providing insight into how they influence each other over time during star formation processes in different environments across various stellar populations.