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EI2GYB > ASTRO 11.11.25 18:30l 51 Lines 4467 Bytes #999 (0) @ WW
BID : 47484_EI2GYB
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Subj: Totally-eclipsing binary UZ Draconis inspected with TESS
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Totally-eclipsing binary UZ Draconis inspected with TESS
Astronomers from Keele University in the UK have utilized NASA's planet-hunting TESS telescope to investigate a totally-eclipsing binary known as UZ Draconis. Results of the new observations, published October 31 on the arXiv pre-print server, put more constraints on the properties of this system.
Eclipsing binaries (EBs) are systems consisting of two stars that orbit each other in a plane along our line of sight. Therefore, the two components eclipse and transit one another, which is seen in the light curves of these systems as periods of practically constant light, with periodic drops in intensity.
Detached eclipsing binaries (dEBs) are crucial for astronomers testing stellar models. This is due to the fact that the masses and radii of both stars can be directly measured from the light and radial velocity curves of the system. Among dEBs, of special interest are those systems experiencing total eclipses because the times of contact during eclipse enable the radii of the stars to be measured to the highest precision.
UZ Draconis is one such totally-eclipsing dEB, consisting of two F-type stars in a circular orbit with a period of 3.26 days. Previous observations of UZ Draconis have found that the primary star has a radius of 1.295 solar radii and a mass of 1.306 solar masses.
The radius of the secondary star was measured to be 1.144 solar radii, while its mass was estimated to be 1.203. Data from ESA's Gaia satellite yielded a distance to the system of approximately 604.37 light years.
Now, a team of astronomers led by Keele University's John Southworth, has revisited UZ Draconis with TESS, hoping to determine the parameters of this system with higher precision than ever before.
"It has been observed by the Transiting Exoplanet Survey Satellite in 41 sectors, yielding a total of 664,809 high-quality flux measurements. We model these data and publish radial velocities to determine the physical properties of the system to high precision," the researchers explain.
Based on the new TESS observations, the masses of the primary and secondary stars were determined to be 1.291 and 1.193 solar masses, respectively. This yields a mass ratio of the system at a level of approximately 0.92.
The sizes of the two components of UZ Draconis were also found to be slightly smaller than previously estimated. The radius of the primary star was measured to be 1.278 solar radii, while the radius of its companion was derived to be 1.122 solar radii.
Furthermore, the distance to UZ Draconis was established to be 605.4 light years, which is consistent with Gaia measurements. In general, the determined properties of this system suggest an age of about 600 million years and a slight super-solar metallicity.
The astronomers added that the light curves of UZ Draconis show starspot modulation on the orbital period, which indicates that the stars are tidally synchronized. However, they found no evidence for pulsations, orbital eccentricity, or changes in the orbital period.
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