HD 65907

Characteristics

HD 65907 is classified as an F9.5V star, meaning it sits on the main sequence and is currently converting hydrogen into helium in its core. Standard stellar models suggest it should be about 4.6 billion years old, similar to the age of the Solar System, and would normally be considered a population I star. However, the star’s chemical makeup and its path through the galaxy point strongly to it being a population II star, which would make it roughly 11 billion years old. To reconcile this apparent contradiction, astronomers believe HD 65907 is a blue straggler, formed when two stars, each less than half the mass of the Sun, merged about five billion years ago. The star has 1.02 times the Sun’s mass and 1.07 times its radius, and it shines with 1.30 times the Sun’s luminosity. Its surface temperature gives it a yellowish-white color, typical of a star near the boundary between spectral types F and G. An infrared excess has been detected around HD 65907, indicating the presence of a debris disk. This disk extends to a radius of 96 astronomical units and has a temperature of 30 Kelvin. HD 65907 is the primary component of a triple star system, also cataloged as Gliese 294 or WDS J07578-6018. Its two companions, HD 65907 B and C (or Gliese 294 B and C), are both red dwarfs with a combined spectral class of M0.5V and apparent magnitudes of +9.88 and +13.5, respectively. The pair orbits the F-type primary at a separation of 60.6 arcseconds, with an estimated orbital period of 22,000 years. The two red dwarfs themselves are separated by 2.468 arcseconds and circle each other roughly once every 270 years.