NASA has found nearly 100 quadruple star systems
TESS's mission is to find exoplanets. More specifically, its mission is to find exoplanets around nearby bright stars. The Transiting Exoplanet Survey Satellite can also study the mass, density, size and orbit of those planets.
But TESS's field of view is large, much wider than its predecessor, the Kepler Space Telescope. . Its range of wide-field cameras scanned 85% of the sky and collected an enormous amount of data. Scientists use machine learning and the collaboration of citizens eager to sift through that data.
To find these systems, there was a collaboration between the NASA Goddard Space Flight Center (GSFC) Astrophysics Science Division and the MIT Kavli Institute. But the professionals of those research institutes needed help. This help came from seven expert citizen scientists who assisted in the painstaking effort of pixel-by-pixel analysis of the light curves. Researchers have focused their efforts on identifying triple and quadruple star systems, but the results go beyond those multiple star systems. Quadruple star systems contain two pairs of eclipsing binary stars (EB). However, these transits and eclipses can be difficult to intercept, which explains the help of dedicated citizen scientists.
if (jQuery ("# crm_srl-th_scienze_d_mh2_1"). Is (": visible")) { console.log ("Edinet ADV adding zone: tag crm_srl-th_scienze_d_mh2_1 slot id: th_scienze_d_mh2"); } The researchers were only interested in specific quadruple star systems and deliberately excluded others. These quadruple systems are in the catalog because they exhibit observable changes in human time scales. "The reason is that for the purposes of this work, our interests are in tight quadruple systems that can exhibit dynamically interesting interactions on a human time scale (months or years)," explain the researchers.
If TESS finds a pair of EBs separated by two TESS pixels and if the EBs are 500 parsecs from us, it means that the EBs are separated from each other by a maximum of 20,000 AU. At that vast distance from each other, it may take generations of human observations to notice any interactions between the stars. The systems must be closer to each other to show interesting interactions observable in months or years, so they must be in the same TESS pixel. This is what necessitated painstaking pixel-by-pixel analysis.
if (jQuery ("# crm_srl-th_scienze_d_mh3_1"). Is (": visible")) {console.log ("Edinet ADV adding zone : tag crm_srl-th_scienze_d_mh3_1 slot id: th_scienze_d_mh3 "); } The systems in the catalog survived a rigorous testing process. The team also found many false positives. There were also triple star systems whose eclipse model mimicked a quadruple star system. In their summary, the authors wrote that "The target stars have been identified through visual inspection and show two series of eclipses with two distinct periods, each with primary and, in most cases, secondary eclipses. All targets have been checked uniformly and passed a series of tests, including pixel-by-pixel motion analysis. "
Multiple star systems can reveal a lot about stellar evolution paths. Astronomers and astrophysicists are interested in stellar stages of evolution such as short-term binaries, common envelope events, type Ia supernovae and black hole mergers.
The arrangement of stars in multiple systems is also evidence of how stars were formed. "For example, the mass ratios between the individual components of a quadruple system, the period ratios between the constituent binary systems, and the reciprocal inclination provide important information on whether the system formed through a core fragmentation scenario or of the disk or aggregation by gravitational capture, ”they wrote.
Another interesting aspect of multiple star systems concerns the planets. Astronomers have found some planets around multiple star systems, but their origins and fate are unclear. In 2015, astronomers discovered a massive planet in the quadruple star system 30 Arietis. According to this discovery, the system is home to a huge gas giant ten times more massive than Jupiter. It was the second known case of a planet in a quadruple star system.
if (jQuery ("# crm_srl-th_scienze_d_mh4_1"). Is (": visible")) {console.log ("Edinet ADV adding zone: tag crm_srl-th_scienze_d_mh4_1 slot id: th_scienze_d_mh4 "); } In 2019, researchers found a unique quadruple star system in which stars are at right angles to the disk of gas and dust that surrounds them. Planets will likely form from this protoplanetary disk. How unusual would the view from the surface of a planet be in that system? The research team is not done yet. They say they have detected several false positives with respect to the controlled detections and that the complete analysis is beyond the scope of this document.
