Astronomers Find Mysterious Dust-Spewing Object Blocking Up to 75% of Host Star's Light

Astronomers have spotted a mysterious object in a distant star system that erratically emits dust that shrouds its star, obscuring its light by as much as 75 percent.

The researchers behind the discovery believe that what they have found is a binary star system with an orbiting body that emits clouds of dust that block light from its stellar hosts.

The team, including Harvard-Smithsonian Center for Astrophysics astronomer Karen Collins, used the Transiting Exoplanet Survey Satellite (TESS) to make the discovery. The primary mission of TESS is to spot exoplanets as they pass in front of their apparent stars, causing a usually minute dip in brightness.

The research is discussed in a paper published in The Astronomical Journal.

Thus far TESS, launched in 2018, has discovered over 4,700 suspected exoplanets—planets outside the solar system—with 172 confirmed. In addition to this, the satellite has built up a catalog called the TESS Input Catalog (TIC) containing over 1 billion objects.

Searching through a catalog of data gathered by TESS with a machine algorithm developed from the observations of cosmic objects that vary in brightness, the team found the mysterious variable object TIC 400799224.

The existence of TIC 400799224 was indicated by a rapid drop in brightness as great as 25 percent in just four hours. This was followed by several other variations in brightness.

Brian Powell, lead author of the paper and data scientist in the NASA High Energy Astrophysics Science Archive Research Center (HEASARC), explained to Newsweek why artificial intelligence (AI) has become vital in searching the universe for cosmic events and objects. He said: "Astronomy and Data Science are converging by necessity. The sheer volume of data collected by modern observatories is beyond human capacity for pure manual examination.

"AI, machine learning, and data science techniques must be leveraged against astrophysical data in order to fully exploit it for discovery."

The astronomers followed up on the object with a range of telescopes, many of which have been operating longer than TESS. This enabled them to determine that one of the stars in the probable binary star system has a light-output that pulsates every 19.77 days.

This is likely the result of an orbiting body that emits clouds of dust. While the pulsations of the system are regular, the blockages of light caused by the dust are erratic in their shape, size, depth, and duration.

The authors wrote: "The cloud is also fairly optically thick, blocking up to 37 percent or 75 percent of the light from the host star." This depends, they said, on which star in the system is the object's true host.

This means the object is emitting a lot of dust. Objects that commonly do this are in the process of disintegration. This object's periodicity, however, has remained stable in the six years since its discovery. This indicates that whatever this object is, it is still currently intact despite producing copious amounts of dust.

"It is somewhat rare to see an eclipse obscuring this much of a star's light, especially from a body that is not solid," Powell said. "What is particularly notable about the behavior of this system is that the eclipse does not always occur, but when it occurs, it is strictly periodic.

"This indicates that the mysterious object—likely a disintegrating planet or asteroid—is orbiting the host star but is accompanied by a dust cloud of an ephemeral nature. We believe that the dust cloud is caused by collisions involving the object."

Suspects for this dust production suggested in the paper include regular collisions between bodies orbiting the stars or an object disintegrating around the stars as the heat causes material to change rapidly from solid to gas—a process called sublimation.

The authors concluded: "Further observations may allow for greater detail to be gleaned as to the origin and composition of the occulter, as well as to a determination of which of the two stars comprising TIC 400799224 is the true host star of the dips."

The discovery of this mysterious dust-spewing object adds to a list of wonderous and remarkable cosmic objects contained in TIC, including objects resulting from stellar pulsations, shocks from supernovae, disintegrating planets, and much more.

Powell said: "I am a data scientist, not an astrophysicist, just lucky enough to be working with data that constitutes the mysteries of the universe."

Correction 01/06/22 9:33 am ET: This article was updated to state Brian Powell is a data scientist in the NASA High Energy Astrophysics Science Archive Research Center (HEASARC), rather than an IT specialist at NASA.

Tess and TIC 400799224
An illustration of the exoplanet hunting TESS and the dust emitting TIC 400799224. The mystery object was spotted via a drop in brightness of 25 percent in an object observed by TESS. Powell et al., 2021/MIT

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