Follow-up Imaging of Disk Candidates from the Disk Detective Citizen Science Project: New Discoveries and False-Positives in WISE Circumstellar Disk Surveys

• Main Authors: Silverberg, Steven M, Kuchner, Marc J, Wisniewski, John P, Bans, Alissa S, Debes, John H, Kenyon, Scott J, Baranec, Christoph, Riddle, Reed, Law, Nicholas, Teske, Johanna K, Burns-Kaurin, Emily, Bosch, Milton K. D, Cernohous, Tadeas, Doll, Katharina, Luca, Hugo A. Durantini, Hyogo, Michiharu, Hamilton, Joshua, Finnemann, Johanna J. S, Lau, Lily, Collaboration, the Disk Detective
• Format: Journal Article
• Language: English
• Published: 25-09-2018
• Subjects: Physics - Earth and Planetary Astrophysics
• DOI: 10.48550/arxiv.1809.09663

The Disk Detective citizen science project aims to find new stars with excess
22-$\mu$m emission from circumstellar dust in the AllWISE data release from the
Wide-field Infrared Survey Explorer (WISE). We evaluated 261 Disk Detective
objects of interest with imaging with the Robo-AO adaptive optics instrument on
the 1.5m telescope at Palomar Observatory and with RetroCam on the 2.5m du Pont
telescope at Las Campanas Observatory to search for background objects at
0.15''-12'' separations from each target. Our analysis of these data lead us to
reject 7% of targets. Combining this result with statistics from our online
image classification efforts implies that at most $7.9\% \pm 0.2\%$ of
AllWISE-selected infrared excesses are good disk candidates. Applying our false
positive rates to other surveys, we find that the infrared excess searches of
McDonald et al. (2012), McDonald et al. (2017), and Marton et al. (2016) all
have false positive rates $>70\%$. Moreover, we find that all thirteen disk
candidates in Theissen & West (2014) with W4 signal-to-noise >3 are false
positives. We present 244 disk candidates that have survived vetting by
follow-up imaging. Of these, 213 are newly-identified disk systems. Twelve of
these are candidate members of comoving pairs based on \textit{Gaia}
astrometry, supporting the hypothesis that warm dust is associated with binary
systems. We also note the discovery of 22 $\mu$m excess around two known
members of the Scorpius-Centaurus association, and identify known disk host
WISEA J164540.79-310226.6 as a likely Sco-Cen member. Thirty-one of these disk
candidates are closer than $\sim 125$ pc (including 27 debris disks), making
them good targets for direct imaging exoplanet searches.