Peter Pan Disks: Long-lived Accretion Disks Around Young M Stars. (arXiv:2001.05030v1 [astro-ph.SR])

Peter Pan Disks: Long-lived Accretion Disks Around Young M Stars. (arXiv:2001.05030v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Silverberg_S/0/1/0/all/0/1">Steven M. Silverberg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wisniewski_J/0/1/0/all/0/1">John P. Wisniewski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuchner_M/0/1/0/all/0/1">Marc J. Kuchner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lawson_K/0/1/0/all/0/1">Kellen D. Lawson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bans_A/0/1/0/all/0/1">Alissa S. Bans</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Debes_J/0/1/0/all/0/1">John H. Debes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Biggs_J/0/1/0/all/0/1">Joseph R. Biggs</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bosch_M/0/1/0/all/0/1">Milton K.D. Bosch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Doll_K/0/1/0/all/0/1">Katharina Doll</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Luca_H/0/1/0/all/0/1">Hugo A. Durantini Luca</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Enachioaie_A/0/1/0/all/0/1">Alexandru Enachioaie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hamilton_J/0/1/0/all/0/1">Joshua Hamilton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holden_J/0/1/0/all/0/1">Jonathan Holden</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hyogo_M/0/1/0/all/0/1">Michiharu Hyogo</a>, the <a href="http://arxiv.org/find/astro-ph/1/au:+Collaboration_Disk_Detective/0/1/0/all/0/1">Disk Detective Collaboration</a>

WISEA J080822.18-644357.3, an M star in the Carina association, exhibits
extreme infrared excess and accretion activity at an age greater than the
expected accretion disk lifetime. We consider J0808 as the prototypical example
of a class of M star accretion disks at ages $gtrsim 20$ Myr, which we call
“Peter Pan” disks, since they apparently refuse to grow up. We present four
new Peter Pan disk candidates identified via the Disk Detective citizen science
project, coupled with textit{Gaia} astrometry. We find that WISEA
J044634.16-262756.1 and WISEA J094900.65-713803.1 both exhibit significant
infrared excess after accounting for nearby stars within the 2MASS beams. The
J0446 system has $>95%$ likelihood of Columba membership. The J0949 system
shows $>95%$ likelihood of Carina membership. We present new GMOS optical
spectra of all four objects, showing possible accretion signatures on all four
stars. We present ground-based and textit{TESS} lightcurves of J0808 and 2MASS
J0501-4337, including a large flare and aperiodic dipping activity on J0808,
and strong periodicity on J0501. We find Pa$beta$ and Br$gamma$ emission
indicating ongoing accretion in near-IR spectroscopy of J0808. Using observed
characteristics of these systems, we discuss mechanisms that lead to accretion
disks at ages $gtrsim20$ Myr, and find that these objects most plausibly
represent long-lived CO-poor primordial disks, or “hybrid” disks, exhibiting
both debris- and primordial-disk features. The question remains: why have
gas-rich disks persisted so long around these particular stars?

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