The Kepler Space Telescope, launched in 2009, revolutionized astronomy by discovering thousands of exoplanets in over 150,000 star systems. Kepler was specially developed in order to record planets in earth size by monitoring stars on periodic brightness discounts, which can result from planets that are present in front of their star compared to the observer. This technique, which is known as a transit method (or transit photometry), has made it possible to identify astronomers to identify the majority of more than 6,000 exoplanets in the current census. However, the method is not perfect and creates some false positive aspects (initially up to 5%–10%), which can sometimes be caused by other heavenly objects.
According to the new investigations by a team of astronomers from the Chinese Academy of Sciences (CAS), this was the case with KOI-1755, a star that was 982 light years from the earth and was regularly weaker. As you have given in her study recently published in the Astrophysical Journal, the transit signal was a false positive positive that was caused by a binary in the shade. The research team was carried out by Ph.D. Candidate Wang Haozhi under the supervision of Prof. Ali Esamdin at the Xinjiang Astronomical Observatory of the CAS (XAO).
For the first time, Kepler recognized a transit-like event from Koi-1755 in 2014 and again in 2021, both of which corresponded to a period of about 25 days. On the second occasion, the signal was interpreted as a possible indication of a planet with 5.9 Erdradii (or 0.5 Jupiter radii), which makes it comparable to a size with a neptune gas giant. Despite this periodic dimming, the true source of the signals has remained a mystery. In order to determine the actual source of dimming, the CAS team analyzed data from Kepler’s target pixel files (TPFS).
It subjects this data to the river modeling at the pixel level. Centroid postponement measurements and cross matching with the third data publication of the GAIA Mission (DR3). This modeling strategy significantly improved the quality of the Kepler light curves, and the DR3 data enabled them to avoid contamination from nearby stars. This made it possible for the team to isolate the non -contaminated light curve from the background star, which confirmed that it was caused by a binary date in the shade.
In short, your analysis showed that the system is not a single star, but consists of two dwarf stars with an orbital period of about 6.14 days. In addition to solar eclipses, her analysis showed that the binary system has regular modulations caused by star spots and differential rotation. This study has not only clarified the true source of the signals from Koi-1755, but also the effectiveness of the photometric modeling methods developed by Wang and his colleagues at the pixel level. It also shows that there could still be an invaluable amount of information about the amendics embedded in Kepler and K2 mission data.
The method could also be promising to examine other transit-like signals in the Kepler archives and other missions based on the transit method to recognize exoplanets, such as:
Further reading: CAS, The Astronomical Journal
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