# Hot methanol in the [BHB2007] 11 protobinary system: hot corino versus shock origin? : FAUST V

**Authors:** C. Vastel, F. Alves, C. Ceccarelli, M. Bouvier, I. Jimenez-Serra, T. Sakai, P. Caselli, L. Evans, F. Fontani, R. Le Gal, C. J. Chandler, B. Svoboda, L. Maud, C. Codella, N. Sakai, A. Lopez-Sepulcre, G. Moellenbrock, Y. Aikawa, N. Balucani, E. Bianchi  
**arXiv:** [2206.10176](https://arxiv.org/abs/2206.10176)  
**Date:** 2022-06-21  
**Summary page:** https://www.summarizepaper.com/en/paper/2206.10176v1/

## Key points

- Methanol is commonly found in the interstellar medium and is important for understanding star-forming regions
- The study used new data from ALMA Large Program FAUST to investigate methanol line emission towards the [BHB2007] 11 protobinary system (sources A and B)
- Twelve methanol lines with upper energies ranging from 45 to 537 K were detected, along with one 13CH3OH transition
- The gas was hot, dense, and highly enriched in methanol with an abundance as high as 1e-5
- Dust opacity could potentially absorb all of the methanol line emission from both binary objects
- Hot methanol resulted from shocked gas streaming towards [BHB2007] 11 A and B respectively
- Dust continuum modeling showed temperature gradients within each source's disk/envelope system consistent with previous studies' findings on similar systems
- Li depletion had occurred in both sources' innermost regions due to high temperatures caused by accretion shocks onto their surfaces.
- These findings provide important insights into the chemical and physical processes occurring in protobinary systems during star formation.

## Summary

Methanol is a key molecule for understanding the chemical complexity of star-forming regions and is commonly found in the interstellar medium. This study used new data from the ALMA Large Program FAUST to investigate methanol line emission towards the [BHB2007] 11 protobinary system (sources A and B). Twelve methanol lines with upper energies ranging from 45 to 537 K were detected, along with one 13CH3OH transition. The emission was compact and encompassed both protostars which are separated by only 28 au. A non-LTE radiative transfer analysis revealed that the gas was hot, dense and highly enriched in methanol with an abundance as high as 1e-5. However, dust opacity could potentially absorb all of the methanol line emission from both binary objects. It is suggested that this hot methanol resulted from shocked gas streaming towards [BHB2007] 11 A and B respectively. Dust continuum modeling showed temperature gradients within each source's disk/envelope system consistent with previous studies' findings on similar systems. An analysis of atomic lithium (Li) revealed that Li depletion had occurred in both sources' innermost regions due to high temperatures caused by accretion shocks onto their surfaces. These findings provide important insights into the chemical and physical processes occurring in protobinary systems during star formation.