# The Planet Formation Potential Around a 45 Myr old Accreting M Dwarf

## TL;DR

This study investigates the cold gas and dust properties of a 45-million-year-old M dwarf with unusual infrared excess and active accretion, using ALMA observations to understand its potential for planet formation.

## Contribution

First ALMA observations of a 45 Myr old M dwarf with active accretion and infrared excess, revealing dust but no cold gas, informing planet formation potential.

## Key findings

- No cold CO gas detected, ruling out a gas-rich protoplanetary disk.
- Detected dust consistent with collisional cascade from large bodies.
- Dust migration via stellar wind could explain infrared excess.

## Abstract

Debris disk detections around M dwarfs are rare, and so far no gas emission has been detected from an M dwarf debris disk. This makes the 45 Myr old M dwarf WISEJ080822.18-644357.3 a bit of a curiosity; it has a strong infrared excess at an age beyond the lifetime of a typical planet-forming disk, and also exhibits broad H$\alpha$ emission consistent with active accretion from a gaseous disk. To better understand the cold gas and dust properties of this system, we obtained ALMA observations of the 1.3mm continuum and the CO/$^{13}$CO/C$^{18}$O J=2-1 emission lines. No cold CO gas is detected from this system, ruling out a gas-rich protoplanetary disk. Unresolved dust continuum emission is detected at a flux of 198$\pm$15 $\mu$Jy, consistent with 0.057$\pm$0.006 M$_{\oplus}$ worth of optically thin dust, and consistent with being generated through a collisional cascade induced by large bodies at radii $<$16 au. With a sufficiently strong stellar wind, dust grains released in the outer disk can migrate inwards via PR drag, potentially serving as a source of grains for the strong infrared excess.