Mysterious dusty object discovered by astronomers using NASA’s TESS Planet Hunter
The transiting exoplanet study satellite, TESS, was launched in 2018 with the aim of discovering small planets around the closest neighboring stars to the Sun. TESS has so far discovered 172 confirmed exoplanets and compiled a list of 4703 candidate exoplanets. Its sensitive camera takes images that cover a vast field of view, more than twice the area of the constellation Orion, and TESS has also assembled a TESS Entry Catalog (TIC) with over a billion objects. . Tracking studies of TIC objects have shown that they result from stellar pulsations, supernova shocks, disintegrating planets, self-lensing gravitational binary stars, eclipses of triple star systems, disc occultations , etc
CFA astronomer Karen Collins was part of a large team that discovered the mysterious variable object TIC 400799224. They searched the catalog using machine learning-based computing tools developed from the observed behaviors of hundreds of thousands of known variable objects; the method has already found planets and decaying bodies that emit dust, for example. The unusual source TIC 400799224 was spotted by chance due to its rapid drop in brightness, nearly 25% in just about four hours, followed by several sharp changes in brightness that could each be interpreted as an eclipse.
Astronomers have studied TIC 400799224 with a variety of facilities, some of which have been mapping the sky for longer than TESS has been running. They found that the object is likely a binary star system, and that one of the stars pulsates with a period of 19.77 days, likely from an orbiting body that periodically emits clouds of dust that obscure the star. But while the periodicity is strict, stardust occultations are erratic in shape, depth, and duration, and are only detectable (at least from the ground) about a third of the time or less.
The nature of the orbiting body itself is puzzling as the amount of dust emitted is significant; if it were produced by the disintegration of an object like the asteroid Ceres in our solar system, it would only survive about eight thousand years before disappearing. Yet, remarkably, during the six years of observation of this object, the periodicity has remained strict and the dust-emitting object has apparently remained intact.
The team plans to continue monitoring the object and incorporate historical observations of the sky to try to determine its variations over several decades.
Reference: “Mysterious Dust-emitting Object Orbiting TIC 400799224” by Brian P. Powell, Veselin B. Kostov, Saul A. Rappaport, Andrei Tokovinin, Avi Shporer, Karen A. Collins, Hank Corbett, Tamás Borkovits, Bruce L. Gary, Eugene Chiang, Joseph E. Rodriguez, Nicholas M. Law, Thomas Barclay, Robert Gagliano, Andrew Vanderburg, Greg Olmschenk, Ethan Kruse, Joshua E. Schlieder, Alan Vasquez Soto, Erin Goeke, Thomas L. Jacobs, Martti H. Kristiansen, Daryll M. LaCourse, Mark Omohundro, Hans M. Schwengeler, Ivan A. Terentev and Allan R. Schmitt, December 8, 2021, The Astronomical Journal.