“Against All Odds” – NASA’s Tess Planet-Hunting discovers a unique star system with six “suns” (weekend feature)



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TESS mission

“The system exists against all odds,” said Brian Powell, a data scientist at NASA’s High Energy Astrophysics Archives Research Center of the source of the starlight that mysteriously illuminated and dimmed at about 1,900 light years. The source, named TIC 168789840, is a system of three pairs of binary stars: three different stellar couplets revolving around three different centers of mass, but the trio remaining gravitationally bound to each other and encircling the galactic center as a single system of stars.

“The mere fact that it exists turns my mind upside down,” said first author, Powell. “I would love to be in a spaceship, park next to this thing and see it in person.”

Eclipses in the curves of light

TESS’s scope of observation encompasses almost the entire sky, allowing the identification of many candidate multiple star systems through analysis of eclipses in light curves. A collaboration between NASA’s Goddard Space Flight Center and the MIT Kavli Institute, working with visual experts, has found more than 100 candidates for triple and quadruple systems.

Most systems are quads

The vast majority of the candidate triple and quadruple star systems discovered by TESS are quadruple, followed by triples since he began searching the galaxy for exoplanets in 2018. But the star light source that mysteriously lit and dimmed about 1900 light years away, “Robin George Andrews reports for The New York Times,” could surpass all of these findings for its sci-fi greatness. “

“Although quadruple systems are much rarer than triple systems,” reports NASA, “the large outer orbit of the third star in a hierarchical triple, necessary for stability, greatly reduces the likelihood that the eclipse or the occultation of the third star is visually noticed in a TESS light curve. Beyond quadruple stars, the likelihood of systems with more stars being identified by photometry alone is low, as the formation of sixfold systems is probably quite rare. This low probability is compounded by the requirement that each binary should be oriented in such a way that they all eclipse. “

A unique system

Although several other six-star systems have been discovered, Andrews reports of NASA’s TESS discovery, this is the first in which the stars of each of these three pairs pass in front and behind the other, eclipsing the another member of his stellar ballet. , at least from the point of view of the TESS space telescope.

“These are the types of signals that algorithms really struggle with,” said lead author Veselin Kostov, NASA postdoctoral researcher at Goddard Space Flight Center. “The human eye is extremely good at finding patterns in data, especially non-periodic patterns like those we see in the transits of these systems.”

Although the star system’s exoplanets have not yet been confirmed, only one of the pairs could have planets. Two of the binaries in the system rotate very close to each other, forming their own quadruple subsystem. All the planets there would likely be ejected or swallowed up by one of the four stars. The third binary is further away, orbiting the other two once every 2,000 years or so, making it a possible exoplanetary refuge.

Its origin a mystery

“The origin of this whirling six-star system will remain a puzzle until we find others like it,” concludes Andrews. “The mere fact that it exists turns my mind upside down,” said first author, Powell. “I would love to be in a spaceship, park next to this thing and see it in person.”

In 2019, TESS discovered its TOI 1338 its first circular planet, a world orbiting two stars, 1300 light years from the constellation Pictor. The two stars rotate in orbit every two weeks. One is about 10% more massive than our Sun, while the other is cooler, darker, and only a third of the Sun’s mass. TOI 1338 b, the only known planet in the system. It is about 6.9 times the size of Earth, or between the sizes of Neptune and Saturn. The planet orbits in almost exactly the same plane as the stars, so it experiences regular stellar eclipses.

The Daily Galaxy, Jake Burba, via Goddard Space Flight Center, NASA Arxiv.org PDF and New York Times Science

Image Credit: NASA / MIT / TESS Shows the spacecraft’s mosaic of 13 southern sky sectors, recorded over the course of a year. One object shown in the mosaic is a long shiny edge of our Milky Way galaxy.



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