16 research outputs found
Disk Detective: Discovery of New Circumstellar Disk Candidates through Citizen Science
The Disk Detective citizen science project aims to find new stars with 22
micron excess emission from circumstellar dust using data from NASA's WISE
mission. Initial cuts on the AllWISE catalog provide an input catalog of
277,686 sources. Volunteers then view images of each source online in 10
different bands to identify false-positives (galaxies, background stars,
interstellar matter, image artifacts, etc.). Sources that survive this online
vetting are followed up with spectroscopy on the FLWO Tillinghast telescope.
This approach should allow us to unleash the full potential of WISE for finding
new debris disks and protoplanetary disks. We announce a first list of 37 new
disk candidates discovered by the project, and we describe our vetting and
follow-up process. One of these systems appears to contain the first debris
disk discovered around a star with a white dwarf companion: HD 74389. We also
report four newly discovered classical Be stars (HD 6612, HD 7406, HD 164137,
and HD 218546) and a new detection of 22 micron excess around a previously
known debris disk host star, HD 22128.Comment: 50 pages, accepted for publication in the Astrophysical Journa
The TESS Triple-9 Catalog II: a new set of 999 uniformly-vetted exoplanet candidates
The Transiting Exoplanet Survey Satellite (TESS) mission is providing the
scientific community with millions of light curves of stars spread across the
whole sky. Since 2018 the telescope has detected thousands of planet candidates
that need to be meticulously scrutinized before being considered amenable
targets for follow-up programs. We present the second catalog of the Plant
Patrol citizen science project containing 999 uniformly-vetted exoplanet
candidates within the TESS ExoFOP archive. The catalog was produced by fully
exploiting the power of the Citizen Science Planet Patrol project. We vetted
TESS Objects of Interest (TOIs) based on the results of Discovery And Vetting
of Exoplanets DAVE pipeline. We also implemented the Automatic Disposition
Generator, a custom procedure aimed at generating the final classification for
each TOI that was vetted by at least three vetters. The majority of the
candidates in our catalog, TOIs, passed the vetting process and were
labelled as planet candidates. We ruled out candidates as false positives
and flagged as potential false positives. Our final dispositions and
comments for all the planet candidates are provided as a publicly available
supplementary table.Comment: 17 pages, 11 figures, 5 tables. Accepted for publication on MNRA
Follow-up Imaging of Disk Candidates from the Disk Detective Citizen Science Project: New Discoveries and False Positives in WISE Circumstellar Disk Surveys
The Disk Detective citizen science project aims to find new stars with excess 22 m emission from circumstellar dust in the All WISE data release from the Wide-field Infrared Survey Explorer. We evaluated 261 Disk Detective objects of interest with imaging with the Robo-AO adaptive optics instrument on the 1.5 m telescope at Palomar Observatory and with RetroCam on the 2.5 m du Pont Telescope at Las Campanas Observatory to search for background objects at 0 1512 separations from each target. Our analysis of these data leads us to reject 7% of targets. Combining this result with statistics from our online image classification efforts implies that at most7.9%0.2% of All WISE-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. and Marton et al. all have false-positiverates >70%. Moreover, we find that all 13 disk candidates in Theissen & West with W4 signal-to-noise ratio >3are 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 Gaia astrometry, supporting the hypothesis that warm dust is associated with binary systems. We also note the discovery of 22 m excess around two known members of the ScorpiusCentaurus association, and we identifyknown disk host WISEA J164540.79-310226.6 as a likely Sco-Cen member. Thirty of these disk candidates arecloser than 125 pc (including 26 debris disks), making them good targets for both direct-imaging exoplanetsearches
Peter Pan Disks: Long-lived Accretion Disks Around Young M Stars
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 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 likelihood of Columba membership. The J0949 system
shows 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 and Br 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 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?Comment: 25 pages, 17 figures. Accepted for publication in the Astrophysical
Journa
Follow-up Imaging of Disk Candidates from the Disk Detective Citizen Science Project: New Discoveries and False Positives in WISE Circumstellar Disk Surveys
The Disk Detective citizen science project aims to find new stars with excess 22 μm emission from circumstellar dust in the AllWISE data release from the Wide-field Infrared Survey Explorer. We evaluated 261 Disk Detective objects of interest with imaging with the Robo-AO adaptive optics instrument on the 1.5 m telescope at Palomar Observatory and with RetroCam on the 2.5 m 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 leads us to reject 7% of targets. Combining this result with statistics from our online image classification efforts implies that at most 7.9% ± 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. and Marton et al. all have false-positive rates >70%. Moreover, we find that all 13 disk candidates in Theissen & West with W4 signal-to-noise ratio >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 Gaia astrometry, supporting the hypothesis that warm dust is associated with binary systems. We also note the discovery of 22 μm excess around two known members of the Scorpius–Centaurus association, and we identify known disk host WISEA J164540.79-310226.6 as a likely Sco-Cen member. Thirty of these disk candidates are closer than ~125 pc (including 26 debris disks), making them good targets for both direct-imaging exoplanet searches
Spitzer Follow-up of Extremely Cold Brown Dwarfs Discovered by the Backyard Worlds: Planet 9 Citizen Science Project
We present Spitzer follow-up imaging of 95 candidate extremely cold brown dwarfs discovered by the Backyard Worlds: Planet 9 citizen science project, which uses visually perceived motion in multiepoch Wide-field Infrared Survey Explorer (WISE) images to identify previously unrecognized substellar neighbors to the Sun. We measure Spitzer [3.6]–[4.5] color to phototype our brown dwarf candidates, with an emphasis on pinpointing the coldest and closest Y dwarfs within our sample. The combination of WISE and Spitzer astrometry provides quantitative confirmation of the transverse motion of 75 of our discoveries. Nine of our motion-confirmed objects have best-fit linear motions larger than 1'' yr⁻¹; our fastest-moving discovery is WISEA J155349.96+693355.2 (μ ≈ 2.”15 yr⁻¹), a possible T-type subdwarf. We also report a newly discovered wide-separation (~400 au) T8 comoving companion to the white dwarf LSPM J0055+5948 (the fourth such system to be found), plus a candidate late T companion to the white dwarf LSR J0002+6357 at 5 5 projected separation (~8700 au if associated). Among our motion-confirmed targets, five have Spitzer colors most consistent with spectral type Y. Four of these five have exceptionally red Spitzer colors suggesting types of Y1 or later, adding considerably to the small sample of known objects in this especially valuable low-temperature regime. Our Y dwarf candidates begin bridging the gap between the bulk of the Y dwarf population and the coldest known brown dwarf
Spitzer Follow-up of Extremely Cold Brown Dwarfs Discovered by the Backyard Worlds: Planet 9 Citizen Science Project
We present Spitzer follow-up imaging of 95 candidate extremely cold brown
dwarfs discovered by the Backyard Worlds: Planet 9 citizen science project,
which uses visually perceived motion in multi-epoch WISE images to identify
previously unrecognized substellar neighbors to the Sun. We measure Spitzer
[3.6]-[4.5] color to phototype our brown dwarf candidates, with an emphasis on
pinpointing the coldest and closest Y dwarfs within our sample. The combination
of WISE and Spitzer astrometry provides quantitative confirmation of the
transverse motion of 75 of our discoveries. Nine of our motion-confirmed
objects have best-fit linear motions larger than 1"/yr; our fastest-moving
discovery is WISEA J155349.96+693355.2 (total motion ~2.15"/yr), a possible T
type subdwarf. We also report a newly discovered wide-separation (~400 AU) T8
comoving companion to the white dwarf LSPM J0055+5948 (the fourth such system
to be found), plus a candidate late T companion to the white dwarf LSR
J0002+6357 at 5.5' projected separation (~8,700 AU if associated). Among our
motion-confirmed targets, five have Spitzer colors most consistent with
spectral type Y. Four of these five have exceptionally red Spitzer colors
suggesting types of Y1 or later, adding considerably to the small sample of
known objects in this especially valuable low-temperature regime. Our Y dwarf
candidates begin bridging the gap between the bulk of the Y dwarf population
and the coldest known brown dwarf.Comment: accepted for publication in The Astrophysical Journa