Scientists have discovered new values for the orbital period and mass in the binary star system of 40 Eridanus, represented by white and red dwarfs.
40 Eridani BC is a famous double star, observed by many scientists. She was characterized in 1867 by William Dawson. It is 16 light-years distant and is visible without any problems even in amateur equipment. Knowing the frequency of rotation around the center of mass and distance, we can determine the mass of each. But this is an unusual system.
This figure shows a new orbital solution. Micrometric observations are marked with a green pole, photographic with purple stars, adaptive optics with blue circles, CCD with purple triangles, and four new speckles with blue stars.
When analyzing, we found out that one of the objects is represented by a white dwarf, and a weak neighbor is red. The second type is considered “normal” and the most common among stars. But this white dwarf is the second most striking in its form, which can be found in an ordinary telescope. For 6 nights of 2017, researchers monitored the system using speckle interferometry. For this, a USNO 66-centimeter refractor telescope was needed. Asaph Hall observed Martian satellites in 1877 in this lens.
The first orbital calculations showed a discrepancy between the mass of the white dwarf from the orbital motion and the redshift. The last detailed analysis eliminated the problem. The new data show that the components of the system rotate with a period of 230.29 years (+/- 0.68 years), which is two decades less than the previous results. The mass of a white dwarf is 0.573 (+/- 0.018) solar.