# An HST/STIS View of Protoplanetary Disks in Upper Scorpius: Observations of Three Young M-Stars

**Authors:** Samuel Walker, Maxwell Millar-Blanchaer, Bin Ren, Paul Kalas, John Carpenter  
**arXiv:** [2104.06447](https://arxiv.org/abs/2104.06447)  
**Date:** 2021-04-13  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2104.06447v1/

## Key points

- Samuel Walker and colleagues observed three protoplanetary disks in visible scattered light around M-type stars in the Upper Scorpius OB association
- The team used the STIS instrument on the Hubble Space Telescope to observe the disks around stars 2MASS J16090075-1908526, 2MASS J16142029-1906481, and 2MASS J16123916-1859284
- Classical subtraction was found to be the most reliable reduction technique for their observations
- Two of the three disks were tentatively detected and exhibited structure out to projected distances of over 200 au - structures at these distances from the host star have never been previously detected at any wavelength for either disk
- Visible-wavelength observations can provide valuable insights into our understanding of protoplanetary disk structures and their evolution around young M-type stars in our galaxy

## Summary

In a recent study, Samuel Walker and colleagues present their observations of three protoplanetary disks in visible scattered light around M-type stars in the Upper Scorpius OB association. The team used the STIS instrument on the Hubble Space Telescope to observe the disks around stars 2MASS J16090075-1908526, 2MASS J16142029-1906481, and 2MASS J16123916-1859284. While all three disks had been previously detected with ALMA, 2MASS J16123916-1859284 had never before been imaged at scattered light wavelengths. The researchers processed their images using Reference Differential Imaging and compared and contrasted three reduction techniques - classical subtraction, Karhunen-Loeve Image Projection (KLIP), and Non-Negative Matrix Factorisation (NMF). They found that the classical method was the most reliable for their observations. Of the three disks observed, two were tentatively detected (2MASS J16142029-1906481 and 2MASS J16123916-1859284), while the third went undetected. The two detections were shown to be consistent when varying the reference star or reduction method used. Both detections exhibited structure out to projected distances of over 200 au - structures at these distances from the host star have never been previously detected at any wavelength for either disk. These findings illustrate the utility of visible-wavelength observations in probing the distribution of small dust grains at large angular separations. The authors suggest that future studies should continue to explore this technique as a means of detecting new features in protoplanetary disks. Moreover, they emphasize that such observations can provide valuable insights into our understanding of protoplanetary disk structures and their evolution around young M-type stars in our galaxy.