Type of site | Citizen science project |
---|---|
Available in | English, Spanish, German, Polish, Chinese, Indonesian, Hungarian, Romanian, Russian, Portuguese |
Created by | Disk Detective Team |
URL | www |
Commercial | No |
Registration | Optional |
Launched | 31 January 2014 |
Current status | Online |
Disk Detective is the first NASA-led and funded-collaboration project with Zooniverse. [1] It is NASA's largest crowdsourcing citizen science project [2] aiming at engaging the general public in search of stars, which are surrounded by dust-rich circumstellar disks, where planets usually dwell and are formed. [3] [4] Initially launched by NASA Citizen Science Officer, Marc Kuchner, the principal investigation of the project was turned over to Steven Silverberg. [5]
Disk Detective was launched in January 2014, and was expected to continue until 2017. [6] In April 2019 Disk Detective uploaded partly classified subjects, as Zooniverse did stop to support the old platform for projects, [7] which was completed in May 2019. [8] The project team began working on Disk Detective 2.0 [9] that was then launched May 24, 2020, utilizing Zooniverse's new platform. [10]
The project invites the public to search through images captured by NASA's Wide-field Infrared Survey Explorer (WISE) [11] and other sky surveys. Disk Detective 1.0 compared images from the WISE mission to the Two Micron All Sky Survey (2MASS), the Digitized Sky Survey (DSS) and the Sloan Digital Sky Survey (SDSS). Version 2.0 compares WISE images to 2MASS, Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), Australia's SkyMapper telescope, and the unblurred coadds of WISE imaging (unWISE).
The images in Disk Detective have all been pre-selected to be extra bright at wavelengths where circumstellar dust emits thermal radiation. They are at mid-infrared, near-infrared and optical wavelengths. Disks are not the only heavenly objects that appear bright at infrared wavelengths; active galactic nuclei, galaxies, asteroids and interstellar dust clouds also emit at these wavelengths. Computer algorithms cannot distinguish the difference, so it is necessary to examine all images by "eye" to make sure that the selected candidates are stars with disks, and not other celestial objects.
After the initial and subsequent discovery of several Peter Pan disks — M dwarf primordial gas-rich circumstellar disk systems that retain their gas 2 to 10 times longer than that of other disks—by the Disk Detective science team, research began to understand how these unusual systems fit into disk development. On September 29, 2022, NASA announced version 2.1 of the project, releasing new data containing thousands of images of nearby stars located in young star-forming regions and to provide a better view of "extreme" debris disks —circumstellar disks that have brighter than expected luminosity—in the galactic plane. The 2.1 dataset targets stars with brightness at a wavelength of 12 μm in an effort to discover more Peter Pan disks. [12]
At the Disk Detective website, the images are presented in animated forms which are called flip books. Each image of the flip book is formatted to focus on the subject of interest within a series of circles and crosshairs. [13]
Website visitors—whether or not they are registered member users of Zooniverse—examine the flip book images and classify the target subjects based on simple criteria. Disk Detective 2.0 elimination criteria include whether the subject "moves" off the center crosshairs in 2MASS images only, if it moves off of crosshairs in two or more images, if the subject is not round in Pan-STARRS, SkyMapper, or 2MASS images, if it becomes extended beyond the outer circle in WISE images, and if two or more images show objects between the inner and outer circles. The ideal target is classified as a "good candidate," and is further vetted by the advanced research group into a list of "debris disk of interest" (DDOI) candidates. Particular interest is paid to good candidates that have two or more images where objects other than the subject are present within the inner circle only. [13]
The selected disk candidates will eventually become the future targets for NASA's Hubble Space Telescope and its successor, the James Webb Space Telescope. They will also be the topic for future publications in scientific literature.
The disks that NASA's scientists at the Goddard Space Flight Center aim to find are debris disks, which are older than 5 million years; and young stellar object (YSO) disks, which are younger than 5 million years.
Volunteers who have registered as citizen scientists with Zooniverse can join an exclusive group on the Disk Detective project, called "advanced users" or "super users," after they have done 300 classifications. Advanced users might then further vet candidates marked as "good," compare candidate subjects with literature, or analyze follow-up data. [14] [15] This advanced user group is similar to other groups that have formed in citizen science projects, such as the Peas Corps in Galaxy Zoo. [16]
The Disk Detective project discovered the first example of a Peter Pan disk. At the 235th meeting of the American Astronomical Society the discovery of four new Peter Pan disks was presented. Three objects are high-probability members of the Columba and Carina stellar associations. The forth object has an intermediate likelihood of being part of a moving group. All four objects are young M dwarfs. [17] [18]
The project has also discovered the first debris disk with a white dwarf companion (HD 74389) [19] and a new kind of M dwarf disk (WISE J080822.18-644357.3) in a moving group. [20] The project found 37 new disks (including HD 74389) and four Be stars in the first paper [19] and 213 newly-identified disk candidates in the third paper. [15] Together with WISE J080822.18-644357.3, the Disk Detective project found 251 new disks or disk candidates. The third paper also found HD 150972 (WISEA J164540.79-310226.6) as a likely member of the Scorpius–Centaurus moving group, 12 candidates that are co-moving binaries and 31 that are closer than 125 parsec, making them possible targets for direct imaging of exoplanets. [15]
Additionally, the project published the discovery a nearby young brown dwarf with a warm class-II type circumstellar disk, WISEA J120037.79−784508.3 (W1200−7845), located in the ε Chamaeleontis association. Found 102 parsecs (~333 lightyears) from the Sun, this puts it within the solar neighborhood, making it ideal for study since brown dwarfs are very faint due to their low masses of about 13-80 MJ. Therefore, it is within distance to observe greater details if viewed with large telescope arrays or space telescopes. W1200-7845 is also very young, with measurements putting it at about 3.7 million years old, meaning that—along with its relatively close proximity—it could serve as a benchmark for future studies of brown dwarf system formation. [21]
A study with JWST MIRI found that the disk around WISEA J044634.16-262756.1B, which was first discovered by the Disk Detective project, has a carbon-rich disk. The study found clear evidence that the disk has long-lived primordial gas. 14 molecules were found within the disk, many of them being hydrocarbons. [22]
The project did make estimates about the amount of high-quality disk candidates in AllWISE and lower-limit false-positive rates for several catalogs, based on classification false-positive rates, follow-up imaging and literature review. Out of the 149,273 subjects on the Disk Detective website 7.9±0.2% are likely candidates. 90.2% of the subjects are eliminated by website evaluation, 1.35% were eliminated by literature review and 0.52% were eliminated by high-resolution follow-up imaging (Robo-AO + Dupont/Retrocam). From this result AllWISE might contain ~21,600 high quality disk candidates and 4-8% of the disk candidates from high-quality surveys might show background objects in high-resolution images, which are bright enough to affect the infrared excess. [15]
The project also has a database that is available through the Mikulski Archive for Space Telescopes (MAST). It contains the "goodFraction", describing how often a source was voted as a good source on the website, as well as other information about the source, such as comments from the science team, machine learned classification, cross-matched catalog information and SED fits. [23]
A group at MIT did use the Disk Detective classifications to train a machine-learning system. They found that their machine-learning system agreed with user identifications of debris disks 97% of the time. The group has found 367 promising candidates for follow-up observations with this method. [24] [25]
Zooniverse projects:
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main-sequence stars. Their mass is approximately 13 to 80 times that of Jupiter (MJ)—not big enough to sustain nuclear fusion of ordinary hydrogen (1H) into helium in their cores, but massive enough to emit some light and heat from the fusion of deuterium (2H). The most massive ones can fuse lithium (7Li).
A rogue planet, also termed a free-floating planet (FFP) or an isolated planetary-mass object (iPMO), is an interstellar object of planetary mass which is not gravitationally bound to any star or brown dwarf.
Cha 110913−773444 is an astronomical object surrounded by what appears to be a protoplanetary disk. It lies at a distance of 529 light-years from Earth. There is no consensus yet among astronomers whether to classify the object as a sub-brown dwarf or a rogue planet.
NGC 2547 is a southern open cluster in Vela, discovered by Nicolas Louis de Lacaille in 1751 from South Africa. The star cluster is young with an age of 20-30 million years.
Wide-field Infrared Survey Explorer was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009. WISE discovered thousands of minor planets and numerous star clusters. Its observations also supported the discovery of the first Y-type brown dwarf and Earth trojan asteroid. WISE performed an all-sky astronomical survey with images in 3.4, 4.6, 12 and 22 μm wavelength range bands, over ten months using a 40 cm (16 in) diameter infrared telescope in Earth orbit.
An object with a spectral type Y is either a brown dwarf or a free-floating planetary-mass object. They have temperatures below around 500 Kelvin and are colder than T-dwarfs. Y-dwarfs have a similar spectrum when compared to the giant planet Jupiter.
HD 74389 is a double star system approximately 425 light years from Earth. The primary, HD 74389 A, was initially listed in the Hipparcos catalog as an A0V spectral type star, but this was subsequently updated in 1990 as A2V when Sanduleak and Pesch imaged it with the Burrell Schmidt telescope at Kitt Peak.
WISE J080822.18-644357.3, also called J0808, is a 45+11
−7 Myr old star system in the Carina constellation with a circumstellar debris disk orbiting an M-type red dwarf about 331 lightyears from Earth.
Backyard Worlds: Planet 9 is a NASA-funded citizen science project which is part of the Zooniverse web portal. It aims to discover new brown dwarfs, faint objects that are less massive than stars, some of which might be among the nearest neighbors of the Solar System, and might conceivably detect the hypothesized Planet Nine. The project's principal investigator is Marc Kuchner, an astrophysicist at NASA's Goddard Space Flight Center.
WISEA 1101+5400 is a T-type brown dwarf approximately 100 light-years away in the constellation Ursa Major. It was discovered in March 2017 by members of the citizen science project Backyard Worlds. Initial photometric analysis suggested it was a T5.5 dwarf, which was later confirmed by a spectrum of the object obtained with the NASA Infrared Telescope Facility. It is the first confirmed brown dwarf found by the project.
LSPM J0207+3331 is a cold and old white dwarf that hosts a circumstellar disk, located 145 light-years from Earth. It was discovered in October 2018 by a volunteer participating in the Backyard Worlds citizen science project. Until 2021 it was the oldest and coldest white dwarf known to host a disk. The white dwarf WD 2317+1830 with a detected disk is at least twice as old and around 2,000 K colder.
A circumplanetary disk is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a planet. They are reservoirs of material out of which moons may form. Such a disk can manifest itself in various ways.
A Peter Pan disk is a circumstellar disk around a star or brown dwarf that appears to have retained enough gas to form a gas giant planet for much longer than the typically assumed gas dispersal timescale of approximately 5 million years. Several examples of such disks have been observed to orbit stars with spectral types of M or later. The presence of gas around these disks has generally been inferred from the total amount of radiation emitted from the disk at infrared wavelengths, and/or spectroscopic signatures of hydrogen accreting onto the star. To fit one specific definition of a Peter Pan disk, the source needs to have an infrared "color" of , an age of >20 Myr and spectroscopic evidence of accretion.
The Tucana-Horologium association (Tuc-Hor), or Tucana Horologium moving group, is a stellar association with an age of 45 ± 4 Myr and it is one of the largest stellar associations within 100 parsecs. The association has a similar size to the Beta Pictoris moving group (BPMG) and contains, like BPMG, more than 12 stars with spectral type B, A and F. The association is named after two southern constellations, the constellation Tucana and the constellation Horologium.
Planet Patrol is a NASA citizen science project available in Zooniverse and aimed at discovering new exoplanets with data from the TESS telescope.
WISE 1534–1043 is a brown dwarf, Class Y, the coolest class, visible only in the infrared. It was accidentally discovered via the Wide-field Infrared Survey Explorer.
WISEA J181006.18-101000.5 or WISEA 1810-1010 is a substellar object in the constellation Serpens about 8.9 parsec or 29 light-years distant from earth. It stands out because of its peculiar colors matching both L-type and T-type objects, likely due to its very low metallicity. Together with WISEA 0414−5854 it is the first discovered extreme subdwarf (esd) of spectral type T. Lodieu et al. describe WISEA 1810-1010 as a water vapor dwarf due to its atmosphere being dominated by hydrogen and water vapor.
WISEA J120037.79-784508.3, also called W1200-7845 or 2MASS J12003792-7845082, is a brown dwarf with a primordial disk 333.73 ± 3.13 lightyears from Earth in the 3.7+4.6
−1.4 Myr-old ε Chamaeleontis association, currently making it the closest known brown dwarf with an associated circumstellar disk. It was discovered by citizen scientists in 2020 volunteering for the Disk Detective project.
Delorme 1 is a binary star with a planetary-mass companion (PMC) or protoplanet in a circumbinary orbit. The PMC is notable for showing signs of accretion, despite being 30-45 Myr old, making it similar to Peter Pan disks. These disks show characteristics of a gas-rich disk at unexpected high ages.
WISEA J044634.16-262756.1 is a binary star system with one component having a long-lived primordial disk, also called a Peter Pan disk.
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