The Planet Formation Potential Around a 45 Myr old Accreting M Dwarf. (arXiv:1812.04124v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Flaherty_K/0/1/0/all/0/1">Kevin M. Flaherty</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hughes_A/0/1/0/all/0/1">A. Meredith Hughes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mamajek_E/0/1/0/all/0/1">Eric E. Mamajek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Murphy_S/0/1/0/all/0/1">Simon J. Murphy</a>
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
$<$16 au. With a sufficiently strong stellar wind, dust grains released in the
outer disk can migrate inwards via PR drag, potentially serving as a source of
grains for the strong infrared excess.
Debris disk detections around M dwarfs are rare, and so far no gas emission
has been detected from an M dwarf debris disk. This makes the 45 Myr old M
dwarf WISEJ080822.18-644357.3 a bit of a curiosity; it has a strong infrared
excess at an age beyond the lifetime of a typical planet-forming disk, and also
exhibits broad H$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.
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