Research
Project Overview
Solar System bodies, like asteroids or comets, are considered "active" when they display features like a tail or coma. A coma is a cloud of gas and dust surrounding the object, and usually looks like one or more fuzzy shells. A tail is a stream of gas that extends away from the object. Some objects can have more than one tail.
Multiple mechanisms can cause activity in asteroids, including collisional events or break-up due to fast rotation speeds. Activity can also occur episodically; for example, when icy objects get close to the Sun, the ices can warm up enough to sublimate into gas. Therefore, active asteroids are important clues to understanding where volatiles, including water, exist in our solar system.
Activity occurrence rates are estimated to be about 1 in 10,000 in the asteroid Main Belt. In order to identify these rare objects, we must observe as many asteroids as possible over the span of many years. HyperActive Asteroids invites volunteers to help discover active asteroids in archival images taken with the Subaru Telescope Hyper Suprime-Cam.
The goals of HyperActive Asteroids include:
- identifying new active asteroids;
- identifying new episodes of activity in known active objects;
- determining which objects display repeated episodes of activity when approaching the Sun, a sign of volatile sublimation;
- and assessing links between activity and an object’s orbital characteristics.
Procedure
We extract individual thumbnails of asteroids from the publicly accessible archive of images taken with the Hyper Suprime-Cam (HSC) mounted on the 8.2-meter Subaru Telescope located on Maunakea in Hawai’i. The HSC data are extremely deep, typically 25th magnitude or greater (around 30 million times fainter than what the human eye can see). Since the HSC data are so deep, the faintest activity observed is unlikely to be in any other public dataset, including the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST).
Citizen Scientists are invited to review HSC asteroid thumbnails for signs of activity. Each image is reviewed by up to a dozen volunteers. Below, see a selection of Subaru HSC thumbnails displaying active objects! Objects showing promising signs of activity will be further investigated by our Project Scientists.
Proven Methods: Activity and Citizen Science
The full public HSC dataset contains over 6 million images of over 539,000 unique small bodies. For such a large dataset, Citizen Scientists provide valuable information: up to fifteen volunteer classifications for each image!
Other Zooniverse projects have searched archival images for signs of activity. Our sister project, Active Asteroids, searches for activity in images taken with the Dark Energy Camera (DECam) mounted on the Blanco 4-meter telescope at the Cerro Tololo International Observatory in Chile. This has led to multiple peer-reviewed discoveries of activity in asteroid populations. Another Zooniverse project, Rubin Comet Catchers, searches for cometary activity in images from the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST).
These projects demonstrate that volunteers can reliably detect subtle tails and activity. HyperActive Asteroids will apply these methods to the Subaru HSC, which regularly achieves magnitudes deeper than any previously explored dataset.